Antarctic Wildlife Guide

The remote, ice-covered Antarctic continent and its surrounding Southern Ocean are home to some of Earth’s most unique creatures. These whales, penguins, seals and seabirds have evolved over eons to thrive in this exceptional environment. Antarctica remains one of the world’s best places for observing animals in the wild at close range. As a visitor to their realm, there is nothing quite like seeing your first whale breach on the open water, or fearless penguin totter along the sea ice. Any Antarctica trip is equally a wildlife-viewing adventure, so come prepared for fleeting glimpses and marvelous encounters.

Whales

The krill-rich waters of the Southern Ocean attract Earth’s largest mammals: baleen whales, such as the mighty blue whale and thriving minke, and toothed whales, such as the orca and sperm whale. These magnificent cetaceans migrate to Antarctic waters each year before returning north to breed. Keep your eyes open as you cruise!

Humpback Whales

Humpback whales, with their stocky bodies, are slower than most other whales, but they are very active at the ocean’s surface. They breach and slap their enormous flippers, which can reach one-third of their total body length.

Orca (Killer Whales)

Spectacular to see in the wild, an orca can travel at up to 55km per hour. They are born into a pod of up to 50 closely related animals, which has its own ‘dialect’ of calls and hunts as a pack.

Minke Whales

These small whales are by far the most abundant baleen whales in the Southern Ocean. Fast swimmers and curious, minkes often approach slow-moving vessels, and can occasionally feed in large groups.

Blue Whales

The blue whale is the largest animal that has ever lived. This rare behemoth is distinctive in its habit of showing its flukes when diving. Only about 2300 are thought to exist in the Southern Hemisphere, having been hunted to near extinction.

Fin Whales

The second-largest whale, adult fin whales can reach speeds of 37km per hour and may not feed at all in winter, relying on their accumulated blubber for energy.

Seals

Whether lolling in the sun or diving from the sea ice deep into Antarctica’s icy waters, seals provide some of the continent's best wildlife-viewing. Vast breeding colonies of elephant and fur seals pack the shores of the sub-Antarctic islands, and several of the seven Antarctic species dwell, hidden, in the pack ice.

Crabeater Seals

This krill-eating seal dwells year-round in the pack-ice zone, and has the largest population of all seals. Estimates vary widely, but start at 15 million. Contrary to their name, they do not eat crab. Where to see pack ice

Weddell Seals

Placid, permanent dwellers of the Antarctic, Weddells are the world’s southernmost dwelling mammal. They use their teeth to keep holes in the ice open for diving, and pups learn to swim at one week. Where to see continental ice

Fur Seals

The smallest seal, the fur seal is closely related to sea lions and dogs. They were hunted to near-extinction in the 19th century for their skins, but populations have since rebounded. Where to see sub-Antarctic islands

Southern Elephant Seals

Named for the giant proboscis on the males, this largest of seals lumbers on land but is graceful at sea; they have been known to dive 2km deep, and remain submerged for two hours. Where to see sub-Antarctic islands, Antarctic Peninsula

Leopard Seals

Built for speed, this long, sleek predator has a giant maw that opens to reveal supersharp canines and pointed molars. Where to see southerly sub-Antarctic islands, pack ice

Penguins

For many, the word ‘Antarctica’ immediately conjures up the image of penguins. Nine distinct species roam the region – some live only on the southern islands and one, the lordly emperor penguin, sticks to the continent. Spot them diving for prey, or ashore (or on fast ice) breeding in colonies

Emperor Penguins

Antarctica’s colorful giant, with its golden blaze on the neck, is known for its winter breeding, deep diving and amazing survival skills. Where to see Weddell Sea, Queen Maud Land, Enderby Land and Princess Elizabeth Land, Ross Sea

King Penguins

Slightly smaller than the similarly marked emperors, the king penguin breeds in very large colonies close to the shore. Where to see sub-Antarctic islands

Chinstrap Penguins

Named for the thin black band under their heads, the acrobatic chinstrap can scoot quickly on its belly (‘toboggan’), and leap great distances for a foothold. Where to see Antarctic Peninsula, South Shetland, South Georgia, South Sandwich

Macaroni Penguins

The world’s most abundant penguin has a near-relative in the royal penguin. Distinguish macaronis from other crested species by their orange-plumed ‘eyebrows’ and black chins. Where to see South Georgia, Crozet, Kerguelen, Antarctic Peninsula

Adélie Penguins

This diminutive tuxedo-ed penguin masses in giant breeding colonies all around mainland Antarctica, but they range as far as 600km north in winter. Where to see mainland shores, South Shetland, South Orkney, South Sandwich

Seabirds

You don’t have to be an ornithologist to enjoy birdwatching around the Southern Ocean, with everything from incredible lone wanderers to cacophonous colony-dwellers. Only a very few species breed on the continent proper. On the open ocean, albatrosses wing gracefully alongside ships, and near land, cormorants dive deep for their meals

Albatrosses

Dramatically immortalized in Coleridge’s The Rime of the Ancient Mariner, this majestic bird with the greatest wingspan lives up to its reputation: foraging trips can take several days and extend hundreds of kilometers. Where to see sub-Antarctic islands, at sea

Skuas

The South Polar skua has the distinction of being the world’s most southerly bird: several have actually turned up (lost?) at the Pole. The sturdy skua is both a scavenger and an aggressive hunter. Where to see sub-Antarctic islands, Antarctic Peninsula

Cormorants

Inshore-feeding birds, cormorants are not normally seen out of sight of land. Their presence alongside a ship in the mist is a sure sign of approaching terra firma. Where to see sub-Antarctic islands, Antarctic Peninsula

Petrels

These seabirds come to land only to breed, and myriad species circle the skies of the Southern Ocean. The Antarctic petrel is unique in that it breeds only on the continent. Where to see everywhere

Environment

Antarctica is a continent of extraordinary natural beauty, physical purity and serenity. Many of its features are, simply put, unique. From subglacial lakes, locked away for millennia, to ice-submerged mountain ranges and calving glaciers, the continent is like a living museum of geographical features. Tourism and science are the primary activities in Antarctica today, each with attendant environmental issues. And the continent serves as a rare test case for many global issues, including climate change.

Feature: Fast Facts

  • Average elevation, including the floating ice shelves: 2250m; excluding the ice shelves: 2194m
  • Highest point: Vinson Massif (4897m); highest point of Antarctic Plateau: Dome A (4093m); highest mountain on Antarctic Peninsula: Mt Jackson (3184m)
  • Average thickness of Antarctica’s continental ice: 2200m; average thickness of East Antarctic Ice Sheet: 2200m; West Antarctic Ice Sheet: 1300m
  • Maximum depth of the ice sheet: 4776m (measured near Dome C at S 69° 56’, E 135°12’)
  • Total volume of ice sheets and ice shelves: 28 million cu kilometers
  • Total length of Antarctic coastline: approximately 45,317km; ice shelves make up 18,877km (42% of total); ice 20,972km (46%); and rock 5468km (12%). The coast is dynamic and these totals vary over time
  • Largest ice shelf: Ross Ice Shelf (487,000 sq km, or roughly the size of France). It is several hundred meters thick, and like all ice shelves, it floats
  • Area of Antarctica that is free of ice: 21,745 sq km (about 0.18% of the continent; area slightly larger than Israel)
  • Lowest bedrock elevation: -2555m, in the Bentley Subglacial Trench (S 80°19’, W 110°5’)

Feature: Guidelines for Visitors to the Antarctic

In 2005–07, Antarctic Treaty countries adopted guidelines designed to limit the cumulative impact of visitors. These site-specific rules for the 32 most visited sites in the Antarctic Peninsula, Ross Sea area and sub-Antarctic islands establish a visitor code of conduct, limit landings to certain size ships (some sites prohibit visits by ships carrying more than 200 passengers) and set daily limits on the number of hours a site can be visited.

In 2011, treaty parties established new guidelines, applicable everywhere on the Ice. For the full regulations see www.ats.aq or ask your tour operator.

Protected Areas

  • Know the locations of areas that have been afforded special protection, and observe any restrictions on entry or on activities that can be carried out in and near them.
  • Do not move, remove or damage historic sites or artifacts.
  • Clean boots and clothes of snow and grit before entering sites.

Environment

  • Do not discard garbage on land or at sea. Open burning is prohibited.
  • Do not disturb or pollute lakes or streams.
  • Do not take souvenirs or collect biological or geological specimens, including rocks, bones, eggs, fossils, or parts or contents of buildings.

Scientific Research

  • Do not interfere with scientific research, facilities or equipment.
  • Obtain permission before visiting Antarctic science and logistic-support facilities; confirm arrangements 24 to 72 hours before arriving, and comply strictly with the rules regarding such visits.

Safety

  • Be prepared for severe and changeable weather. Be sure that your equipment and clothing meet Antarctic standards.
  • Know your capabilities and the dangers posed by the Antarctic environment. Plan activities with safety in mind at all times.
  • Take note of, and act on, advice and instructions from your leaders; do not stray from your group.
  • Do not walk onto glaciers or large snowfields without proper equipment and experience; there is a real danger of falling into hidden crevasses.
  • Do not enter emergency refuges (except in emergencies). If you use equipment or food from a refuge, inform the nearest research station or national authority once the emergency is over.
  • Respect any smoking restrictions, and safeguard against fire, a hazard in Antarctica’s dry environment.

The Land

Around 200 million years ago Antarctica was joined with Australia, Africa, South America, India and New Zealand in the supercontinent Gondwana. About 20 million years later, Gondwana began the enormously slow process of breaking into the pieces we recognize today, and the continents, subcontinent and islands began moving into their present positions. Antarctica arrived at the southern pole around 100 million years ago and had forests with mammals and dinosaurs. Fossil evidence includes conifer, fern and reptile species that have also been found in India, South America, Australia and Africa.

Between 34 and 24 million years ago, what is now known as the Drake Passage opened, and the isolation of the continent began. With falling CO₂ levels, Antarctica began to cool dramatically.

Today the continent has a diameter of about 4500km and an area of about 14.2 million sq km (1.4 times the size of the US). This most isolated, arid and highest continent has an average elevation of 2250m, and is classified as a desert.

Antarctica is divided by the 2900km-long Transantarctic Mountains into East Antarctica (sometimes referred to as ‘Greater Antarctica’) and West Antarctica (or ‘Lesser Antarctica’), with the directions deriving from 0° longitude. Antarctica’s highest point is Vinson Massif (4897m).

The rocks of East Antarctica are at least three billion years old, among the oldest on Earth. Some of the oldest terrestrial rock, estimated to be 3.84 billion years old, was found in Enderby Land. West Antarctica is relatively new: only 700 million years old.

The Antarctic Peninsula separates the two great embayments into the continent, the Weddell and Ross Seas, each of which flows in a broad clockwise motion. Each also has its own ice shelf (Ronne Ice Shelf and Ross Ice Shelf, respectively), which are extensions of the great Antarctic ice sheet.

In September, Antarctica’s late winter, the size of the continent effectively doubles with the freezing of the sea ice, which can extend more than 1000km from the coast. The Antarctic coastline is still far from being perfectly charted.

The Antarctic Ice Sheet

Satellite images show that ice covers 99.82% of Antarctica. The Antarctic ice sheet has an area of about 13.3 million sq km (1.7 times the size of Australia). This ice is up to 4776m thick in some locations and on average is about 2200m thick – giving it a total ice volume of about 28 million cu kilometers. In some places its enormous weight has depressed the underlying landmass by nearly 1600m. Antarctica’s continental shelf is about three times deeper than that of any other continent.

This enormous amount of ice has formed through the accumulation of snow over millions of years, and exists in a state of dynamic equilibrium. The amount of snow deposited in any one year is relatively very low – Antarctica is a desert and the driest continent on Earth. Because the snow has been deposited over so many years without melting, the ice sheet provides a natural archive that glaciologists and climatologists study for evidence of past environments and of climatic changes.

When snow is deposited it consolidates to form ice. Due to pressure created by its own weight, the ice flows from the high interior toward the Antarctic coast, where large slabs break off to form icebergs.

Icebergs

The Antarctic ice sheet is the ‘iceberg factory’ of the Southern Ocean. The total volume of ice calved from the ice sheet each year is about 2300 cu kilometers, and it has been estimated that there are about 300,000 icebergs in the Southern Ocean at any one time. Individual icebergs range in dimension from a few meters (often called ‘growlers’) to about 5m (‘bergy bits’) to kilometers.

From time to time particularly large icebergs break off the ice sheet. These can be tens of kilometers to even 100km long. At any one time there might be four or five gigantic icebergs in excess of 50km in length in the Southern Ocean, usually close to the Antarctic coast. In 2000, one of the world’s biggest icebergs – about the size of Connecticut – broke free from the Ross Ice Shelf. It held enough fresh water to supply the world for over a year.

These larger icebergs are tabular in shape and form by calving from the large Antarctic ice shelves (such as the Ross, Filchner or Amery ice shelves). Typically, these icebergs are about 30m to 40m high (above sea level) and as much as 300m deep. After erosion from wind and waves, and melting from the warmer sea temperatures away from the Antarctic coast, the tabular icebergs become unstable and roll over to form jagged irregular icebergs, sometimes with spikes towering up to 60m into the air and with even greater protrusions deep under the ocean surface. Ultimately, icebergs melt completely as they drift to more northerly, warmer water.

Credit

Dr Jo Jacka

Bio

Written by Dr Jo Jacka, Glaciologist and Palaeoclimatologist

Feature: Iceberg Names

Large icebergs – those at least 10 nautical miles (18.5km) long – are given code names that sound like those used for military aircraft: C-16, B-15A, and so on. The codes derive from the quadrant of Antarctica where the icebergs were originally sighted, often by satellite. ‘A’ designates the area from 0° to W 90° (Bellingshausen/Weddell Seas), ‘B’ the area from W 90° to 180° (Amundsen/eastern Ross Seas), ‘C’ the area from 180° to E 90° (western Ross Sea/Wilkes Land), and ‘D’ the area from E 90° to 0° (Amery Ice Shelf/eastern Weddell Sea).

After an iceberg is sighted, the US National Ice Center assigns a quadrant letter and a number based on its point of origin. C-16, for example, is the 16th iceberg tracked in quadrant C since the center began tracking big bergs in 1976. Large icebergs are tracked even after they split, until the pieces are too small to be seen by satellite. Such pieces get a suffix letter after their original name, so B-15A is the first fragment to calve from iceberg B-15.

The Southern Ocean

The Southern Ocean encircles Antarctica in a continuous ring of mainly eastward-flowing water. This water comprises 10% of the world’s oceans, and is the most biologically abundant ocean in the world.

As well as connecting the Atlantic, Pacific and Indian Oceans, the Southern Ocean also isolates the Antarctic continent from warmer waters. The strong westerly winds around Antarctica help form the Antarctic Circumpolar Current. This, the world’s longest current, extends from the sea surface to the ocean floor, and has an average eastward flow rate of 153 million cu meters/second – more than 100 times the combined flow of all the world’s rivers and four times greater than the Gulf Stream. Deep waters from all of the world’s oceans are upwelled here, and the current separates polar waters and their ecosystems from subtropical ones.

The Southern Ocean is also vital in the air–sea exchange of carbon dioxide. Its cold waters naturally absorb massive amounts of CO₂, leading some scientists to study the possibility of deliberately increasing this uptake in order to minimize the impact of global warming.

The Southern Ocean Observing System (SOOS; www.soos.aq) was established in 2011 so scientists can develop methods for monitoring and studying Southern Ocean systems (atmosphere, land, ice, ocean and ecosystems) and their impacts on the rest of the world.

Feature: Ocean Rights

The UN Convention on the Law of the Sea’s ‘Exclusive Economic Zone’ gives a country exclusive use of the resources in its water (such as fish) and on the sea floor. In Antarctica, three of the seven countries claiming Antarctic territories have applied for these rights. If the rights are granted, the nations would still be bound by all of the Antarctic environmental rules, including the mining ban. A country could choose to impose even higher levels of environmental protection. In a pioneering move showing great international cooperation, the Commission for the Conservation of Antarctic Marine Living Resources created the world's largest marine reserve in 2016, protecting 1,548,800 sq km in the Ross Sea area.

Environmental Issues

Despite its isolation, Antarctica is increasingly subject to the same threats and challenges as the rest of the planet. Some major impacts on the Antarctic environment are caused by people who have never even visited. Climate change and ozone depletion, pesticide residue, rubbish and fishing practices all affect Antarctica. As does the impact of visitors.

Exploitation of Marine Life

Sealers were among the first to explore the Antarctic waters and millions of seals were slaughtered up until the end of the 19th century. Whaling became a major industry near the beginning of the 20th century, with most whale species being hunted to near extinction. Although commercial whaling is now prohibited in Antarctica and its surrounding waters, a loophole allowing whaling for research purposes had permitted the Japanese whaling fleet to catch 1000 whales a year, until it was overturned by the International Court of Justice in 2014. As of March 2017, Japan was developing a new whaling plan that was yet to be approved. In the meantime, in the 2016-17 season the nation harvested over 300 minke whales.

Commercial sealing is regulated by the 1978 Convention on the Conservation of Antarctic Seals, although it’s unlikely sealing will return.

Commercial fishing was regulated in 1980 with the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR; www.ccamlr.org), which ensures that the Southern Ocean’s living resources are treated as a single ecosystem. Measures under CCAMLR identify protected species, set catch limits, identify fishing regions, define closed seasons, regulate fishing methods and establish fisheries inspection. It applies south of the Antarctic Convergence, a zone much larger than the Antarctic Treaty area. But illegal fishing continues to be a problem.

Exploitation of Minerals

The Protocol on Environmental Protection prohibits all mining in Antarctica. Iron ore, coal and other minerals have all been found, but their quantities and qualities are still unknown. It is theorized that oil and natural gas exist beneath Antarctica’s continental shelf, but no commercial-size deposits have ever been found. At present, exploiting any of these deposits would be highly uneconomical; the equivalent, in one scientist’s words, of ‘mining on the moon.’

Nevertheless, there was a knotty history to get to the current prohibition on mining, and in 2048 the criteria required to lift or change the ban become less stringent and it must be re-ratified by consensus.

Environmental Impact of Science

Most people in Antarctica and on its surrounding islands are either scientists or support staff at the scientific bases. While today’s science bases are environmentally responsible, this wasn’t always the case. Early on, scientific bases operated without much environmental awareness, burning waste, dumping barrels of oil, and building bases and airstrips in sensitive areas such as penguin rookeries. In 1961, the US’ McMurdo Station installed a nuclear reactor. It was shut down in 1972 and shipped back to the US, along with 101 drums of radioactive earth.

The situation changed in the 1980s when tourists on ships, the first independent visitors, noticed the damage and complained. In the late 1980s and into the 1990s, NGOs, such as Greenpeace, wrote reports and brought independent journalists on expeditions. International pressure on the governments with scientific bases led to greener practices and an understanding that scientific research should be carried out while protecting the environment. A clean Antarctic has great scientific value; a contaminated one does not.

Throughout the '80s many stations were cleaned up, and this major international shift in attitude culminated in the 1991 signing of the Protocol on Environmental Protection. Also known as the Madrid Protocol, it came into force in 1998, and designates Antarctica as a ‘natural reserve, devoted to peace and science.’ It establishes environmental principles for the conduct of all activities; prohibits mining; and subjects all activities to prior assessment of their environmental impacts. Annexes to the protocol detail rules regarding conservation of Antarctic fauna and flora, waste disposal, marine pollution, management of protected areas, and liability arising from environmental emergencies.

Environmental Impact of Tourism

Tourist visitors to the Antarctic far outnumber scientists and support personnel. Consequently, many regulations have been developed to mitigate the environmental impact of tourism.

The classic example of human impact in the Antarctic is a footprint in a moss bed, still visible a decade after it was made. Less obvious is the impact on ‘invisible’ wildlife, such as algae living inside rocks or flora underneath snow.

Animals can be affected even when they don’t show it noticeably in their behavior. German researchers, for instance, found that heart rates of incubating Adélies increased markedly when they were approached by a human still 30m away, even though the birds showed no visible response.

The Protocol on Environmental Protection to the Antarctic Treaty studies the environmental impact of tourism through its Antarctic Site Inventory project, which began field work in 1994. The project is managed by Oceanites, Inc (www.oceanites.org).

In August 2011 a ban on the use and carriage of heavy fuel oil (HFO) imposed by the International Maritime Organization was projected to reduce the number of voyages by 500-plus passenger cruise ships from 12 (in 2010–11) to three (in 2015–16). And 500-plus passenger ships may not land.

Land-based infrastructure for tourism, such as hotels or hard-rock airstrips, is opposed by all environmental NGOs because the environmental impact cannot be justified.

Protected Areas

The Antarctic Treaty System provides for Antarctic Specially Protected Areas (ASPAs), which are designed to preserve unique ecological systems, natural features or areas where research is either underway or planned.

No one is allowed to enter an ASPA without a specific permit. Many ASPAs are not marked, but tour leaders should tell you where they are.

Feature: Aliens in Antarctica

Worldwide, many non-native species (also called ‘alien species’ or ‘aliens’) have invaded and affected virtually every ecosystem. The cost includes the loss of native species and ecosystems. Native biodiversity on sub-Antarctic islands has been heavily impacted by invasive plants and vertebrates, including rats, giant mice, feral cats and weeds (for more examples, see www.issg.org/database).

While the Antarctic continent itself has, so far, escaped the ravages of biological invasion, non-native organisms, including terrestrial invertebrates and plants, and a marine crustacean, have been found surviving in the Antarctic Treaty region. The possibility of successful establishment and development of invasiveness is increasing as growing numbers of visitors from government programs, tourism and fisheries add to the chances of ‘hitchhiking’ organisms arriving in the Antarctic on equipment, containers, clothing or ship hulls. The increasing number of connections between the Arctic and Antarctic regions mean that more organisms originate in a similar climate. Moreover, faster transport increases an organism’s probability of arriving in good shape for survival.

In the longer term, climate change will make the receiving environment more ‘hospitable’ and hence increase the threat of biological invasion.

The issue has been spearheaded by the International Union for Conservation of Nature (IUCN) in Antarctic Treaty meetings since 1998, as well as by international projects during International Polar Year (IPY) 2007–08. One study estimates that during the 2007–08 season, 70,000 seeds arrived with visitors. About one-fifth of tourists and two-fifths of scientists accidentally carried seeds, and half of those seeds hailed from very cold regions, making them ideal candidates for naturalization.

Prevention

Lessons learned in the rest of the world show that preventing the arrival of such non-native organisms is the best approach because of the difficulty and cost of eradicating invaders once they are established. The proactive, preventative approach of Antarctic Treaty parties (and responsible tour operators) includes cleaning boots, gear and clothing and checking Velcro areas – before going to Antarctica – and removing all seeds, soil, or other material of biological origin.

Climate Change & Antarctica

The world’s climate is influenced by many factors, including the amount of energy coming from the sun, the amount of greenhouse gases and aerosols in the atmosphere, and the properties of the Earth’s surface, which determine how much solar energy is retained or reflected. Antarctica has proven central to many climate-change discoveries, as well as vulnerable to many of its impacts.

Feature: Measuring the Ice Sheet & Climate Change

Glaciologists measure the amount of snow falling on the ice sheet and compare this with the amount of ice flowing toward the coast (some moving as fast as 9m a day), and ultimately with the amount of ice breaking off as icebergs or melting in the warmer coastal margins of the continent.

By flying over the ice sheet, or by traversing it with over-snow tractor trains, glaciologists use satellite surveying techniques to measure the ice’s surface height. Ice thickness is measured using downward-looking radars. Global positioning satellites measure the positions of markers in the ice sheet, which over time reveal the speed of the ice flow, and other satellites measure ice extents.

As of 2017, data has shown that at Antarctica's higher elevations the continent may be gaining ice and snow, while the warming coastal ice shelves are losing them. The reasons for this are not yet fully understood.

Ozone Depletion

The spring ozone ‘hole’ over the Antarctic continent was discovered in 1985, and significant ozone decline was observed in northern latitudes as well. Stratospheric ozone depletion is caused by chlorine gas formed from various artificial chemicals such as chlorofluorocarbons (CFCs) and halons.

Sunlight (hence the spring-time hole) and cold temperatures are necessary to complete the release of chlorine gas to destroy the ozone.

Ozone depletion is significant because the hole allows substantially higher levels of ultraviolet-B (UV-B) radiation to reach Antarctica and the Southern Ocean in spring and early summer, the peak period of biological activity. Increased UV levels threaten plankton, the base of the Antarctic marine ecosystem, upon which all life (from fish to seabirds, penguins, seals and whales) depends. Researchers have found a 6% to 12% reduction in marine primary productivity during the period of the hole.

In addition, Antarctic animals and vegetation may become directly damaged by increased UV-B, or by the appearance of shorter wavelength UV-C, the most damaging form of this radiation. Nobody knows yet to what degree Antarctic life can adapt to withstand this increasing stress.

The discovery of the ozone hole and its effects led to the negotiation of the Montreal Protocol on Substances that Deplete the Ozone Layer (entered into force in 1989), an international treaty designed to phase out the production of some substances responsible for ozone depletion. Ozone depleting gases in the Antarctic stratosphere reached a maximum around the year 2006, and are now heading in the right direction, but fluctuate annually, with 2016 experiencing a slightly below-average hole (8.9 million sq miles).

Warming Temperatures

Carbon dioxide and other greenhouse gases warm the surface of the Earth by trapping heat in the atmosphere, which under ‘normal’ circumstances keeps our planet habitable. However, the atmospheric concentrations of greenhouse gases such as carbon dioxide (CO₂), methane (CH4) and nitrous oxide (N₂O) have significantly increased since the beginning of the industrial revolution. This is mainly due to human activities such as the burning of fossil fuels, land-use changes, animal husbandry and agriculture. The atmospheric concentration of CO₂ is now far higher than at any time in the last 650,000 years. It has also been increasing faster in the last few decades than it has since the beginning of continuous measurements around 1960. As a result, global temperatures (and sea levels) are rising.

Global Impacts

The Intergovernmental Panel on Climate Change (IPCC; www.ipcc.ch) was established in 1988 by the World Meteorological Organization and the UN Environment Programme. IPCC assesses scientific information relevant to human-induced climate change, the impacts of human-induced climate change and options for adaptation and mitigation. Its latest report was released in 2014.

There are many observations of increasing air and ocean temperatures. According to the report, 1983–2012 was likely the warmest 30-year span in the last 1400 years in the northern hemisphere. Eleven of the 13 years between 2003 and 2016 rank among the 12 warmest years recorded since 1850. From 1880 to 2012, global temperature has increased by 0.85°C. Regional temperature changes have also been observed, including larger changes in Arctic and Antarctic temperatures (eg 2.8°C in the Antarctic Peninsula from 1951 to 2000 – the highest rise in the world).

Globally, sea level is rising at about 3.2mm each year. Sea levels will rise at different rates in different places. Due to factors such as the Earth’s rotation, the shape of ocean basins, and ocean circulation, the loss of West Antarctica ice, for example, would cause a 15% higher-than-average sea rise along the coastal US.

Effects of climate change have been observed in many natural systems, on all continents and in most oceans. Glaciers are melting; frozen ground is thawing; and damage associated with coastal flooding is increasing. Regional changes include those in sea ice and pack ice, ocean salinity, wind patterns, droughts, precipitation, frequency of heat waves and intensity of tropical cyclones.

Recent changes in climate have already had significant impacts on biodiversity and ecosystems, including changes in species distributions, population sizes, the timing of reproduction or migration, and higher frequency of pest and disease outbreaks.

Projections for the Future

The IPCC estimates that global temperature from the 1980s to the year 2100 will rise by between 1.4°C and 5.8°C if no additional mitigation measures are put in place. It is estimated that up to 30% of plant and animal species could become extinct if the global increase exceeds 1.5°C to 2.5°C. The average warming of inhabited continents is likely to be twice as much as it was during the 20th century.

Global average sea level is expected to rise by 0.9m to 2m during that time (but these calculations do not take into account the possibility that ice could be lost more rapidly).

Other projected changes include acidification of the oceans, reduced snow cover and sea ice, more frequent heatwaves and heavy precipitation, more intense tropical cyclones, and slower oceanic currents.

According to the International Union for Conservation of Nature (IUCN), there is compelling evidence that continued climate change will be catastrophic for much of our biodiversity. Modeling shows that the ranges occupied by many species will become unsuitable for them, and this has already been observed with some Antarctic penguins. Because species will shift habitats at different rates, the community structure of ecosystems will become very disrupted. The same could be true for humans.

Impacts on Antarctica

Antarctica can be likened to an early warning system for global warming. The IPCC suggests that global warming will be greatest in the polar regions. Recent data shows a sustained atmospheric temperature increase of 2.8°C in the western Antarctic Peninsula region since the 1940s. Mean winter air temperatures since the 1950s have increased by 6°C; this is one of the fastest increases in the world.

Consistent with climate change is the rapid disintegration and collapsing of ice shelves in the Antarctic Peninsula and the breaking off of large icebergs. A 2012 study examined satellite data from 1972 to 2011, finding that ice shelves in West Antarctica are steadily losing their grip on land. For example, ESA’s Envisat satellite observed the Larsen B ice shelf losing 4990 sq km of ice from 2002 to 2011.

Melting in West Antarctica contributes approximately 1mm to 2mm per year to global sea rise, but this could increase with the acceleration of ice loss in the region. A 2016 study showed that if CO₂ emissions continue unchecked, the melting of the ice in Antarctica could raise sea levels 15m by the year 2500. Another 2012 study showed that simply thinning ice sheets (as opposed to calving) also accelerates the descent of glaciers to the coast.

A further consequence of increased melting is a decrease in the salinity of the Ross Sea, since freshwater will be added to the sea water.

Scientists have also measured a 20% decline in Antarctic sea-ice extent since the 1950s. This directly influences the breeding success of penguins. In the Peninsula region (where the duration of sea-ice cover has decreased by over 80 days since 1978) the Adélie penguin population has declined by 80%. This is due directly to warming and also because it affects krill reproduction, and hence the amount of food available to krill-feeding penguins.

With changes in climate, and therefore ecosystems, some penguin populations, such as the Adélies, will dwindle. A 2016 study showed that 60% of their habitat could become unlivable by 2100. Chinstraps, which had been thought to be relatively safe since they inhabit more ice-free areas than the Adélies, were shown in a 2012 study to also be declining (a 36% decline in one colony was noted). As with the Adélies, chinstraps are krill-eaters, and so are affected by the ice reduction. Gentoo penguins have a more variable diet, and so their populations are not decreasing due to ice-melt (as at the time of writing).

Ironically, according to a 2012 study, climate change could harm Antarctic fur seal populations because as the weather warms it is also projected to get wetter and windier, making it harder for them to stay warm in their vulnerable early months of life.

International Response

In Rio de Janeiro in 1992, 198 countries including the US signed the UN Framework Convention on Climate Change (www.unfccc.int), a voluntary agreement that contained no legally binding commitments to cut greenhouse gas emissions. A two-year negotiation then resulted in the Kyoto Protocol, which entered into force on February 16, 2005. This legally binding agreement aims to reduce greenhouse gases that cause climate change.

Despite continued debate about the protocol’s costs and benefits, it is considered by many to be the most far-reaching agreement on the environment and sustainable development adopted so far. Most of the world’s countries agreed to ratify and implement it, but not the USA.

The 2009 Copenhagen Summit and 2010 Cancun Agreements continued negotiations to develop next-step accords for keeping global warming below 2°C. In December 2011 the 17th UN Framework Convention on Climate Change in Durban, South Africa, extended the Kyoto Protocol for five years, to 2017.

But, despite earnest efforts both publicly and privately, emissions continued to increase, and results on reaching Kyoto targets were mixed.

In November 2016 the Paris Agreement went into effect. Under this agreement, countries establish Intended Nationally Determined Contributions (INDCs) to reducing greenhouse emissions with the aim of keeping this century's global temperature rise less than 2°C above pre-industrial levels, with an ideal of getting below a 1.5°C increase. Unlike the Kyoto Protocol, these targets are created by the nations, not the treaty, and they are not legally binding (though the reporting and evaluation systems are). The USA did ratify the treaty; notable holdouts as of March 2017 include Russia and the Netherlands. The results of this system remain to be seen.

Innovation in the private sector is another area of potential response to climate-change challenges, with technologies being developed and commercialized.

It remains unclear whether – even with the adherence of the major emission-producing countries – the international targets would definitively reverse the situation.

Sidebar: Shrinking Ice

In 2012 US researchers reported that data from NASA’s GRACE satellites show shrinking ice caps and glaciers led to a 12mm increase in global sea levels from 2003 to 2010. That’s 4.3 trillion tons of ice: enough to cover the United States 0.5m deep.

Sidebar: Ice & Sea Level Rise

Antarctica’s ice sheets contain 90% of the world’s ice, holding about 70% of the world’s fresh water. If they melted, it is estimated the world’s oceans would rise by more than 60m.

Sidebar: World's Largest Glacier

The largest glacier in the world is the Lambert Glacier, which flows onto the Amery Ice Shelf in East Antarctica.

Sidebar: Closing the Ozone Hole

The severity of the ozone hole varies from year to year, depending on the meteorological conditions of the stratosphere during the Antarctic winter. According to 2016 data, it is expected to recover over the next 30 years.

Sidebar: Ice Cores & Greenhouse Gases

Antarctic ice cores reveal that levels of greenhouse gases in the atmosphere and the Earth's temperature are intimately linked.

Sidebar: Rising Sea Levels

Global sea level has risen by 17cm during the 20th century. A rise of 30cm to 50cm caused by melting ice sheets in Antarctica would flood Polynesian islands. If the West Antarctic ice sheet were to become destabilized and ‘slide’ into the sea, it could create a rise of up to 6m.

Sidebar: Antarctica Bottom Water

Antarctic Bottom Water forms when seawater is cooled by air and made saltier by ice formation. It sinks to the ocean floor because it’s denser than surrounding water. Then it travels northward, mixing with warmer waters and affecting the world’s heat balance. In 2017, research showed it’s been warming and freshening – cause unknown.

Sidebar: Pesticides in Seals

Sampling of seal blubber and milk has shown a slow but steady accumulation of pesticides and other organic poisons, transported south from the industries and agriculture of the northern hemisphere.

Sidebar: Antarctic Environmental Monitoring

Many governments now have environmental officers and waste-management programs with environmental-awareness training for all staff in Antarctica. In some cases, they audit the environmental impact of their activities.

Sidebar: Penguins & Climate Change Reading

The Ferocious Summer: Palmer’s Penguins and the Warming of Antarctica, by Meredith Hooper, gives a clear explanation in layperson’s terms of some of the effects of climate change in Antarctica.

Sidebar: CryoSat Ice Measurements

The European Space Agency (www.esa.int) uses ice-measuring satellite CryoSat to measure Antarctica’s ice sheet.

Feature: The Southern Lights

It starts with the faintest of smudges in the night sky – so indistinct that, at first, it could almost be a stray wisp of cloud. But as you watch, the smudge deepens, becomes more solid and blushes green. Suddenly a clear arc of color pierces the dark between the stars. Diffuse rays fall from space in ephemeral curtains that flicker and dance as if being blown by a gentle celestial breeze and the sky erupts into one huge abstract canvas of swirling green and rippling gold, of shimmering red and exploding violet. The light floats across the heavens, brightening to ferocity one minute, then fading away to blackness. Despite the furious riot of color and light above, the only noise you hear is the rush of your breath and the rustle of your clothing. The cold pinches your cheeks and claims your fingers, but still you stand, transfixed by a spectacle as mesmerizing as staring at the embers of an open fire. The display can last for hours, and although the cold will inevitably force a retreat, it is difficult to tear yourself away.

Named after the Roman goddess of the dawn, aurora can occur both in the north (aurora borealis) and in the south (aurora australis). Since ancient times, Arctic peoples have explained the mysterious northern lights in a variety of ways: from torches carried by souls on their way to the spirit world, to the reflection of swarms of herring in the polar seas. Certain tribes in North America believed that a handclap would frighten auroras away, while whistling would bring them closer.

Scientists travel to Antarctica specifically to study auroras – and the cause of the phenomenon is in many ways as astonishing as the display itself. Millions of miles away, the sun produces electrically charged particles that are blown outwards across the solar system in a continuous ‘solar wind.'

As the solar wind passes Earth, the charged particles are attracted by the Earth’s magnetic field and are drawn toward its two geomagnetic poles. As the particles pass through the atmosphere, they interact with atoms, molecules and ions in the upper atmosphere, causing them to release energy as light. Green light is a result of the particles colliding with oxygen molecules, while red and purple light is caused by collisions with nitrogen.

The northern and southern lights occur simultaneously and are almost identical mirror images of each other, but the aurora australis holds a particular mystique because so few people have been lucky enough to observe it. The majority of people visit Antarctica in austral summer when daylight hides auroral activity. It is only dark enough to see the aurora australis from April to October. Even then, a full moon or cloudy skies will reduce visibility.

The best locations for watching the aurora australis are in some of the most inaccessible parts of Antarctica. Most aurora australis occur in a thick ring (known as the Auroral Zone) around the south geomagnetic pole (near Vostok station). The exact position of the Auroral Zone moves from day to day but usually covers the coast of Queen Maud Land, crosses Marie Byrd Land in West Antarctica, then spreads over the Southern Ocean as far as Macquarie Island. Only very rarely does it venture over the Peninsula, making this an unlikely place to spot the southern lights.

For more on auroras, visit the University of Alaska Fairbanks Geophysical Institute website (www.gi.alaska.edu).

Felicity Aston (www.felicityaston.co.uk) spent three years at Rothera Research Station as a British Antarctic Survey meteorologist; in 2012 she became the first woman to ski across the continent alone.

Credit

Felicity Aston

Bio

Felicity Aston (www.felicityaston.co.uk) spent three years at Rothera Research Station as a British Antarctic Survey meteorologist; in 2012 she became the first woman to ski across the continent alone.

Wildlife

Antarctica is home to an astounding variety of wildlife – including many species found nowhere else on Earth. Many animals have evolved characteristics uniquely suited to life on and around the Ice, and fossil records show bizarre extinct life forms and even dinosaurs. The wild Southern Ocean contains blooms of zooplankton and phytoplankton that support fish, crustaceans and squid. This food chain, with its rich swarms of krill, leads to top predators: whales, seals and seabirds, and of course, penguins.

Feature: Tips for Viewing Wildlife

When viewing Antarctic wildlife, it is important to keep your distance. The 2011 Guidelines for Visitors to the Antarctic require it – and it’s important for your safety and that of the wildlife.

Although Antarctic animals may appear unconcerned by humans nearby, they may in fact be under considerable stress. People as far as 30m from a penguin rookery have been shown to increase the birds’ heart rates significantly. And penguins may deviate from their usual path when approaching or leaving a colony for as long as three days after people visit. The further you stay from an animal, the more natural its behavior will be. For this reason, many biologists prefer to view wildlife through binoculars or telephoto lenses even when ashore.

Guidelines for Visitors to the Antarctic: Wildlife Rules

The taking of, or harmful interference with, Antarctic wildlife is prohibited, except in accordance with a permit.

  • When in the vicinity of wildlife, walk slowly and carefully and keep noise to a minimum.
  • Maintain an appropriate distance from wildlife. While in many cases a greater distance may be appropriate, in general don’t approach closer than 5m (15m for fur seals). Abide by site-specific distance guidelines.
  • Observe wildlife behavior. If wildlife changes its behavior, stop moving or slowly increase your distance.
  • Animals are particularly sensitive to disturbance when they are breeding (including nesting) or molting. Stay outside the margins of a colony and observe from a distance.
  • Every situation is different. Consider the topography and the individual circumstances of the site, as these may have an impact on the vulnerability of wildlife to disturbance.
  • Always give animals the right of way and do not block their access to the sea.
  • Do not feed wildlife, or leave food or scraps lying around.
  • Vegetation (including mosses and lichens) is fragile and very slow growing. Do not walk, drive or land on any moss beds or lichen-covered rocks; stay on established paths.
  • Do not introduce any plants or animals into the Antarctic.

Whales

Whales (cetaceans) generally have long lifespans and are essentially divided into baleen whales (of which the blue whale is the largest) and toothed whales (dolphins, sperm whales and orcas). Baleen whales strain out small crustaceans like krill through the fibrous baleen plates that line their jaws.

Antarctica’s whale species typically migrate north to warm waters for austral winter where they calve. The calves then migrate south with their mothers (repeating the migration together for several years until they are independent) to the food-rich edge of the sea ice in Antarctic spring.

Hunted to near-extinction, some species, such as the mighty blue whale, are now so rare that a sighting will be reason to rejoice. Others, especially the minke, are still abundant.

Feature: Southern Ocean Whaling Controversy

When the Southern Ocean Whaling Sanctuary was established by the International Whaling Commission (IWC) in 1994, Japan was the only nation of the 24 members to oppose it. An exception was then granted, allowing whaling for research purposes. The Japanese whaling fleet had been permitted to catch 1000 minke whales each year under this proviso until it was overturned by the International Court of Justice in 2014. As of March 2017, Japan was developing a new whaling plan that was yet to be approved. In 2016–17, they caught over 300 minkes. Conservation organizations and many scientists object to this whaling as deceptive, as meat from the minkes is sold in markets, used in school-lunch programs and served in kujira-ya (whale restaurants). Sales figures from 2011–12, show a significant decline in the market for whale meat in Japan. Japan’s Institute of Cetacean Research (ICR; www.icrwhale.org) says that it sells the meat to help fund its research, which includes data collected on age, calves and gestation.

The practice has created a lot of contention. The activist group Sea Shepherd Conservation Society (www.seashepherd.org) tries to disrupt whale hunts by pursuing whaling ships and blocking slipways on vessels, preventing whalers from loading whales on board. Although Sea Shepherd’s direct actions have been denounced by many governments, it does have wide support, with prominent celebrities, musicians and sports figures among its backers.

At the IWC’s October 2016 meeting in Slovenia, a South American–led bid for a South Atlantic Whale Sanctuary was up for a vote again (a similar attempt in 2011 ended with Japan and other whaling nations walking out in protest). Despite support from Australia, New Zealand and the US, the vote fell short of the 75% majority required to pass. Japan, Russia, Iceland and Norway were among the nations that voted against the measure.

Blue Whales

The blue whale (Balaenoptera musculus) is one of a group of baleen whales called rorquals (derived from the Norwegian røyrkval, meaning furrow whale), which have longitudinal folds running from below the mouth backwards, allowing their mouths to open very wide. Thus, they can gulp up to 50 tonnes of water, filtering out tiny crustaceans with 250 to 400 pairs of baleen plates. A single blue whale can eat as much as 4.5 tonnes of krill in one day.

The blue whale is the largest animal on Earth, reaching up to 200 tonnes and 33.5m. Blues are found in all oceans; the largest are found further south. The pygmy blue whale (brevicauda), which grows to 25m, lives further north. Blues are usually solitary or travel in pairs.

Commercial whaling severely reduced the species’ numbers: 360,000 blue whales were killed in the 20th century alone. Current estimates put the blue whale population in the southern hemisphere at around 2300; they are classified as endangered.

Fin Whales

The fin whale (Balaenoptera physalus), a baleen whale, is the second-largest whale species, after the blue. Female fin whales attain 27m in length in the southern hemisphere, with males reaching 25m. Unusually, the anterior part of the animal is asymmetrically colored: the left lower jaw is bluish-grey, the right is white.

Fin whales are found in all oceans. The highest population density is away from the sea ice, in temperate and cool waters. In Antarctic waters fin whales feed on krill.

Nearly 750,000 fin whales were killed in the 20th century in the southern hemisphere. They are classified as endangered.

Humpback Whales

Humpback whales (Megaptera novaeangliae) are baleen whales that can be readily recognized by their enormous flippers, which can reach one-third of their total body length. (Its generic name Megaptera means ‘Great wing.’) Humpbacks are normally black, with varying amounts of white on the undersides of their flippers and flukes. Males reach a maximum length of 17.5m, females 19m. Adult humpbacks can reach 40 tonnes.

Humpbacks, found in all oceans, have the longest annual migration of any mammal, and often feed in groups (on krill and small fish). They can migrate from the Antarctic Peninsula to Mexico, up to 25,000km.

Humpbacks were hunted to near extinction as late as the 1960s, but the population has bounced back. There are estimated to be 60,000 humpbacks today; they are divided into 14 distinct groups, nine of which are no longer endangered.

Minke Whales

Following genetic studies, minke whales are now thought to be two separate species: the larger Antarctic minke whale (Balaenoptera bonaerensis) and the smaller dwarf (B. acutorostrata), or common, minke whale. Minke whales are the second-smallest of the baleen whales, although with a maximum length of 10.7m and a mass of up to 10 tonnes, they’re still large animals.

In summer minkes are circumpolar in distribution, with the highest densities seen at the pack-ice edge. In winter most minkes move to lower latitudes. Minkes are the most abundant baleen whales in the Southern Ocean, with a population of possibly half a million. These krill-feeding rorquals are well adapted to the ice: in heavy pack ice, they breathe through the cracks. During whaling years several hundred minkes are killed annually, ostensibly for scientific purposes, by Japanese whalers, although some of the meat is sold for human consumption.

Orca Whales

Orcas (Orcinus orca), also known as killer whales, are the largest members of the dolphin family. Their black-and-white markings and tall dorsal fins (especially in the adult male) are distinctive. Males reach 9m, females nearly 8m. Orcas can weigh 6 tonnes or more.

Orcas occur in all seas, but are more abundant in colder waters. They travel in schools or pods of up to 50 individuals. Orcas feed on squid, fish, birds and marine mammals, including penguins, dolphins and whales. They will tip up small ice floes to get to resting seals, and they have been observed working in teams to ‘swamp’ a floe, sending a wave surging across the ice to wash a seal into the water. Orcas have been spotted at sub-Antarctic Marion Island swallowing king penguins whole.

There are still many killer whales in the Southern Ocean. One estimate puts the worldwide population at 50,000. Recent observations suggest there may be three species of killer whales in the Southern Ocean, a smaller one (O. glacialis) being restricted to the Antarctic pack ice. They have not been caught commercially since 1979–80 (when Soviet whalers killed 916), but they are taken in small numbers for display in captivity.

Sei Whales

Sei whales (Balaenoptera borealis), part of the rorqual group of baleen whales, are the third-largest whales in the Southern Ocean. Females may reach 19.5m and 45 tonnes; males are slightly shorter and lighter.

Sei whales can be found in all oceans, but only larger individuals have been recorded south of the Antarctic Convergence. They occur in small schools of three to eight animals. Seis catch their prey (copepod crustaceans) by skimming, not gulping, water.

Seis were hunted to commercial extinction during the whaling era and have been completely protected since 1979. They number fewer than 12,000 today, and are considered endangered.

Southern Right Whales

Whalers named the slow-moving, inshore-visiting southern right whale (Eubalaena glacialis) ‘right’ because it was relatively easy to row down and harpoon – and then it obligingly stayed afloat to yield its long baleen plates and lots of oil. Southern rights grow up to 17m in length and can weigh up to 90 tonnes. The whitish callosities on the jaw and forehead can be used to identify individuals.

Southern right whales occur in the southern oceans between S 20° and S 50°, and have been recorded around the more northerly of the southern islands. They feed on krill.

Southern rights were over-exploited to commercial extinction as early as the mid-19th century, and full protection came only in 1935. There are estimated to be 7500 today, and they are classified as endangered.

Sperm Whales

The sperm whale (Physeter macrocephalus), of Moby Dick fame, is an unmistakable species with its enormous flat-fronted head and narrow, tooth-filled lower jaw. The largest of the toothed whales, they have as many as 50 teeth (up to 25cm long) in the lower jaw, and the upper jaw (nearly always toothless) contains sockets the lower teeth fit into. Males can reach over 18m in length, females 11m, with males weighing as much as 57 tonnes.

Sperm whales occur in all of the world’s oceans, but rarely in shallow seas. Most sperm whales south of S 40° are adult males. Schools of 20 to 25 individuals are made up of females and their young, joined by males during the October to December breeding season. Sperm whales eat mid- to deep-water squid, some of which reach 200kg; these veritable krakens of the deep are caught in absolute darkness at depths of 3km.

Sperm whales were much exploited in the past for their oil, ambergris and teeth. Now they are fully protected in the Southern Ocean. They are classified as endangered.

Seals

Seven species of seals range from the sub-Antarctic and southern cool-temperate islands to the continent itself. Some are true (earless) seals and others have small flaps over their ears (fur seals) and are related to sea lions (which are present in the Falkland Islands). Some seals breed in colonies, others are restricted to the pack ice, and the elusive Ross Seal is hard to spot anywhere.

Seal populations are currently robust, despite 19th-century hunting, and none are endangered, though all are protected by the Convention for the Conservation of Antarctic Seals.

Antarctic & Sub-Antarctic Fur Seals

Fur seals can be found on most of the circumpolar southern islands – in very large numbers at some of them. Vagrants have reached the southern continents. The Antarctic fur seal (Arctocephalus gazella) occurs further south than its slightly smaller relative, the sub-Antarctic fur seal (A. tropicalis), with which it sometimes hybridizes. Males, at more than 200kg and 2m, far outweigh females, which weigh up to 55kg (at 1.3m).

Fur seals breed in harems, and males can be formidable opponents to rivals and human visitors alike. Male fur seals defend their beachfront territory and give off a strong musk scent when they are breeding. Pupping takes place in December. Fur seals eat squid, fish and crustaceans such as krill. Some Antarctic males kill penguins as well.

Fur seals are now showing a remarkable recovery in numbers since being over-exploited for their coats early in the 19th century – so much so that at some localities, they are displacing breeding albatrosses and killing vegetation, leading to conservation dilemmas. Nearly two million Antarctic fur seals crowd the coastline of Bird Island off South Georgia.

Crabeater Seals

The name ‘crabeater’ (Lobodon carcinophaga) comes from the German word krebs, which refers to crustaceans (such as krill), not just crabs. They have specially adapted teeth with extra projections that form a sieve so they can strain out Antarctic krill, their almost-exclusive diet (not crab), from the water. These slim seals reach about 2.5m in length and 400kg.

Crabeaters breed in spring on the pack ice. The distribution of crabeaters is circumpolar, although they prefer pack ice to open sea. Crabeaters are considered the world’s most abundant seal – some estimates put the population as high as 15 million.

Leopard Seals

Adult male leopard seals (Hydrurga leptonyx) reach a length of 2.8m and weigh 320kg. Females are even larger, at 3.6m and 500kg. Leopard seals have large heads with huge gapes, making them fearsome predators. They’re found among the pack ice in summer and hauled-out on the more southerly sub-Antarctic islands in winter.

Leopards are often solitary, except during the breeding season. Because they live in the pack ice, little is known about their breeding behavior. Pups are born on the ice during summer. The leopards’ diet includes penguins and other seals (especially pups), as well as fish, squid and krill.

Ross Seals

The Ross seal (Ommatophoca rossii) dwells in the densest pack ice and is consequently the least often seen of all Antarctic seals. Named for its discoverer James Clark Ross (leader of the British Antarctic Expedition of 1839–43), this solitary animal is usually found hauled-out onto large floes, alone or in pairs. Females reach 2.4m and 200kg; males are slightly smaller.

When a Ross seal is disturbed, it rears back almost vertically, with its mouth open and throat inflated. They are also known for distinctive vocalizations: trilling, warbling or ‘chugging.’ The Ross seal feeds on squid and fish.

Southern Elephant Seals

The southern elephant seal (Mirounga leonina) is the world’s largest seal. Males grow to 3 tonnes and 5m in length, females 900kg and 3m. They have a circumpolar distribution, and are found on most of the southern islands and on the Antarctic Peninsula.

Males spend winter at sea and first haul out in August, followed by females. Males fight to determine which will be ‘beachmaster,’ with mating rights to a harem of females. Their large proboscis helps create their fearsome roars. Adults use their thick blubber layer (for which they were once hunted) to survive while breeding, during which they do not feed.

Southern elephant seals are known for adaptations that allow them to feed at great depths for prolonged durations (their diet is predominantly squid and fish). They are elongated in shape and have enormous volumes of red-blood-cell-rich blood (useful for storing oxygen when diving), special cavities for storing extra blood, and muscles that also store oxygen.

Weddell Seals

The quintessential Antarctic seals, Weddell seals (Leptonychotes weddellii) reach 3.3m in length and a weight of 500kg and may live for 20 years. Females are slightly larger than males.

Weddell seals have a circumpolar distribution, living further south than any other mammal (except people). They live on fast ice (sea ice attached to shore or between grounded icebergs) year-round, though they are occasionally sighted in pack ice. In October, pups are born in colonies near cracks and holes in the ice that give their mothers access to the sea. Males defend their holes.

Studies have shown Weddells can dive to 720m and stay underwater for more than an hour. Because Weddells use their incisors and canines to keep their breathing holes open, they often wear down their teeth. They have been observed blowing air bubbles into cracks under the sea ice to flush out prey (fish, squid and crustaceans). Weddells are the best studied of the Antarctic seals, because they can be more easily approached over fast ice than can the pack-ice species.

Birds

Approximately 45 species of birds breed south of the Antarctic Convergence, including nine of the 17 species of penguins, and many frequent the skies and waters of the Southern Ocean. Just a very few, however, come to land on the continent to breed.

Penguins

Penguin sexes are similarly marked but sometimes females are smaller. Chicks often huddle in groups called crèches, especially while parents are away hunting.

Penguin species are impacted by changes from global warming, and currently many scientists are studying how this is affecting population numbers and species distribution.

Adélie Penguins

Adélies (Pygoscelis adeliae), the archetypical Antarctic penguin, were named by French explorer Dumont d’Urville after his wife. Purely black and white, thus similar to gentoos and chinstraps, Adélies have a distinctive white eye ring. They weigh 3.9kg to 5.8kg and are 46cm to 75cm in length. Adélies prefer krill, and dive up to 150m, but they usually remain closer to the surface.

Over 3.7 million pairs breed during summer in large colonies all around the Antarctic continent and at some of the more southerly sub-Antarctic islands. They create stone-lined nests and take turns protecting two eggs. They winter in the sea ice and, if possible, return to the same nest and mate the next year.

Chinstrap Penguins

Chinstraps (Pygoscelis antarctica) are black and white like Adélies, but have a distinctive black line below the chin – hence the name. They weigh 3kg to 6kg, with a length of 68cm. The second-most numerous penguin, after the macaroni, 7.5 million pairs of chinstraps have been identified, though warming conditions are causing declines in some zones.

Chinstraps feed on krill and fish near their colonies (around the Antarctic Peninsula and on islands south of the Antarctic Convergence). They lay two eggs in November and chicks fledge by early March. Chinstraps feed both chicks equally (unlike others who feed preferentially). They range north of the pack ice in winter.

Emperor Penguins

The emperor penguin (Aptenodytes forsteri) is the world’s largest penguin, at over 1m (although ancient fossils have been found of penguins measuring 2m) and 40kg.

The known population is 595,000 breeding pairs in 48 locations, and they do not travel north of the Antarctic Convergence. Warming conditions could be an issue for future survival.

The emperor is the only Antarctic bird that breeds in winter. A single egg is incubated on the feet of the males, which group-huddle in the extreme winter cold to reduce heat loss. Meanwhile, females travel across the ice to find polynyas in which to feed. Incubation averages 66 days, and chicks become independent between November and January.

Gentoo Penguins

The black-and-white gentoo (Pygoscelis papua), which grows between 75cm and 90cm, can be distinguished from the slightly smaller Adélie and chinstrap by its orange bill and a white patch above and behind its eye. The estimated 387,000 breeding pairs are circumpolar, inhabiting the sub-Antarctic islands and the Antarctic Peninsula. Large populations occur at South Georgia (100,000 pairs), the Falkland Islands (70,000 pairs) and Îles Kerguelen (30,000 pairs).

At the more northerly sub-Antarctic islands, gentoos breed in winter, laying two eggs as early as July. On the more southerly islands and the Peninsula, laying occurs from October to December.

Gentoos can dive deeper than 100m for prey: krill, fish and squid. The species has been categorized as 'least concern' by the International Union for Conservation of Nature (IUCN).

King Penguins

The king penguin (Aptenodytes patagonicus) is the world’s second-largest penguin, weighing 9kg to 15kg, with a length of 80cm. It is estimated there are approximately 1.6 million pairs. They breed on seven sub-Antarctic island groups, eat primarily lanternfish and squid, and can dive to 300m for 15 minutes.

Kings often breed in very large colonies, close to the shore on rocky terrain. For about 55 days in summer, the parents take turns incubating a single egg on their feet. They can shuffle along slowly to avoid seals. The downy chick is uniformly dark brown, and was once described as the ‘woolly penguin,’ a species of its own. During the long breeding season (14 to 16 months) chicks are reared right through the winter (huddling in crèches to keep warm) and only fledge the following summer, making annual breeding impossible. They breed only twice every three years.

Macaroni Penguins

Orange tassels meeting between the eyes differentiate the macaroni (Eudyptes chrysolophus) from the slightly smaller (and lighter-billed) rockhopper. Macaronis weigh 5.3kg, with a length of 70cm. The krill-eating macaroni penguin is the most abundant of the sub-Antarctic and Antarctic penguins, with 6.3 million pairs in sometimes gigantic colonies on islands near the Antarctic Convergence and off the Peninsula. They have been known to travel up to 10,000km across the oceans during winter.

The summer-breeding macaroni lays two eggs, the first smaller than the second (extremely unusual for birds, but common to all the crested penguins). The first-laid (‘A’) egg is usually kicked out of the nest soon after the ‘B’ egg is laid and only one egg hatches. This system has prompted many studies.

IUCN has classified the macaroni as 'vulnerable' due to recent decreases at some sub-Antarctic breeding locales (attributed to temperature changes reducing available prey).

Rockhopper Penguins

‘Rockies,’ the smallest of the crested penguins (2.3kg to 2.7kg), have lemon yellow tassels that do not meet between the eyes. Two species are now recognized, the southern (Eudyptes chrysocome) and the northern (E. moseleyi), with longer, more luxuriant crests.

Rockhoppers (including both species, an estimated 2.75 million pairs) are both sub-Antarctic and southern cool temperate island breeders. The largest population nests on the Falkland Islands.

They can breed (in a two-egg system like the macaronis) among boulders on exposed shores, where their strong hopping and swimming abilities allow them to transfer from sea to nest sites.

Rockhoppers of both species have decreased dramatically, attributed to sea-temperature rises due to climate change (which affects the availability of prey), thus their IUCN 'vulnerable' status.

Royal Penguins

Royals (Eudyptes schlegeli), which resemble macaronis but have white faces, are found only at sub-Antarctic Macquarie Island. A census in 1984–85 found 850,000 breeding pairs, which is now regarded as an underestimate.

Two eggs (the first of which is discarded) are laid in often-huge coastal colonies in October with chicks fledging by February. In nonbreeding times they have been spotted as far away as Tasmania.

Royals have been classified as 'near threatened' due to their single breeding locality but stable population. Years ago, molting royal penguins, called ‘fats,’ were killed for their oil, but protest against this led to Macquarie Island being made the first sub-Antarctic island nature reserve.

Albatrosses

On the Southern Ocean, entrancing albatross will glide past your ship, but distinguishing the different species is not always easy (depending on the taxonomy, from eight to 17 albatross breed on the islands).

They all lay only one egg at breeding, and some only breed every two years. All albatross feed on squid, fish and crustaceans caught at the sea surface.

Today, many albatross are killed in Southern Ocean longline fisheries. Fishermen spool out baited longlines and the birds drown after they get hooked when diving for the bait. The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR; www.ccamlr.org) has addressed this problem in its jurisdiction by employing streamers to scare the birds away from bait, by ensuring that baited hooks sink faster, and by prohibiting longlining during daylight hours, shifting mortality away from albatrosses. Other dangers include trawl warps, land-based introduced predators and pollution. These issues are being addressed through initiatives such as the Agreement on the Conservation of Albatrosses and Petrels (www.acap.aq) and by NGOs such as BirdLife International (www.birdlife.org). At present, though, the future of all albatross is still a concern, with conservation statuses ranging from endangered (gray-headed albatross) to critically endangered (Amsterdam albatross).

The black-browed albatross (Thalassarche melanophrys) is widespread in the southern seas and breeds at nine island groups including South Georgia and the Falklands. It is one of the smaller-sized group of albatross, sometimes known as mollymawks, but with a 2.5m wingspan and a weight of up to 5kg, it’s still a big bird. They’re white and have yellow bills with red-orange tips and dark lines through the eye, and their underwing pattern features a wide, dark leading edge.

The gray-headed albatross (Thalassarche chrysostoma) can be identified by its grayish head; broad, dark leading edge to the underwing; and orange stripes on both upper and lower mandibles. The gray-head has a circumpolar breeding distribution and can be seen on such islands as South Georgia, and Campbell and Macquarie Islands.

The royal albatross (northern Diomedea epomophora, and southern D. sanfordi) belongs to the ‘great’ albatrosses of the Southern Ocean. They are primarily recognized at sea by their huge size and their all-white tail with mostly black upper wings and a dark edge to the upper mandible, which occur at adulthood. They breed on islands off New Zealand.

Shy albatrosses (Thalassarche cauta) are the largest of the Southern Ocean mollymawks, with a wingspan of up to 2.6m. Distinguishing features are a humpbacked appearance in flight, dark upperwings that are not as black as other mollymawks’ and a narrow dark leading edge to the underwing in both adults and juveniles. The shy albatross is misnamed, since it will approach and follow ships. It breeds on islands south of New Zealand and around Tasmania. However, the bird (now considered to form four species) has a widespread at-sea distribution.

There are two species of sooty albatrosses: the dark-mantled (Phoebetria fusca), usually called the sooty, is uniformly chocolate brown, whereas the light-mantled (P. palpebrata) has a contrasting pale back. The dark-mantled sooty has a yellow sulcus (furrow) along its lower mandible, whereas the light-mantled has a blue one. Both species have circumpolar at-sea distributions, but the light-mantled tends to occur further south, reaching the edge of the pack ice. This is mirrored by their breeding distribution. The paired courtship flights and haunting calls around misty cliffs make for one of the quintessential experiences of visits to Southern Ocean islands.

The wandering albatross (Diomedea exulans) is distinguished from the mollymawk albatrosses by its huge size – with a wingspan of up to 3.5m. It has a white head, neck and body, a wedge-shaped tail, and large pink beak. Wanderers are found in 10 island groups in the Southern Ocean. They can cover vast tracts of the Southern Ocean, flying up to several thousand kilometers on a single foraging trip, so are aptly named. Indeed, young wanderers may not return to land for five years or more, staying at sea the whole time.

Other southern species include the yellow-nosed albatross (Atlantic Thalassarche chlororhynchos and Indian T. carteri), found on remote islands such as Tristan da Cunha, and the Amsterdam albatross (Diomedea amsterdamensis), one of the world’s rarest birds, found only at Île Amsterdam.

Petrels

This group of seabirds got their name because of the habit of the small storm petrels pattering across the sea surface as if they were walking across it. ‘Petrel’ means ‘little Peter,’ the apostle who walked on the water with Christ on the Sea of Galilee. Except for the two biggest species, all petrels remain at sea, coming to land only to dig burrows in which to breed (so protecting themselves from predatory birds such as skuas). Unfortunately, introduced cats and rats on many breeding islands have not been so easily thwarted, and many species are threatened as a consequence.

Many of these birds eat krill, fish and squid, caught mainly by surface-dipping while on the wing. Like albatrosses, some petrels are threatened by longline fishing.

Giant petrels are the largest of the petrel family. The northern giant petrel (Macronectes halli) and the southern giant petrel (M. giganteus) can be distinguished by the color of their bill tips: greenish in northerns, reddish-brown in southerns. Giant petrels can be seen in all parts of the Southern Ocean, with southerns occurring further south – some breed on the Peninsula and in Terre Adélie. Unlike albatrosses, giant petrels forage on both land and sea. On land they kill birds as large as king penguins and scavenge in seal colonies. At sea they eat fish, squid and crustaceans, and scavenge dead cetaceans and seabirds. Giant petrels are caught by tuna and toothfish longline-fishing from vessels in the Southern Ocean.

Antarctic fulmars (Fulmarus glacialoides) are a medium-sized petrel (800g, 1.2m wingspan), readily identified by their pale-gray plumage with white head and black flight feathers. The bill is pink with a dark tip and the dark eye is a distinguishing feature. Antarctic fulmars are a southerly species with a circumpolar distribution at sea and are commonly found on pack-ice fringes. They breed on the islands off the Peninsula, the South Orkney and South Sandwich Islands, along the Antarctic coastline and on Bouvetøya.

The Antarctic petrel (Thalassoica antarctica) is a boldly marked dark-brown-and-white petrel, a little smaller than the Antarctic fulmar. It breeds only on the Antarctic continent; the largest-known colony, Svarthamaren in Queen Maud Land, supports about 250,000 pairs.

Snow petrels (Pagodroma nivea) are unmistakable with their all-white plumage, black bill and small black eyes. They breed on the Antarctic continent and Peninsula, and on Bouvetøya, in no fewer than 298 breeding sites. The snow petrels at-sea distribution does not extend far north; they are very much denizens of the pack-ice zone, where they roost on icebergs.

Prions (Pachyptila spp.), also known as whalebirds, are small gray-blue-and-white birds. They can be distinguished from blue petrels by their black terminal band to the upper tail. All have a vague M shape visible on their upper parts when in flight. There may be as many as six species. Breeding takes place at many southern islands, with one or two species occurring together. They can be seen in all areas of the Southern Ocean north of the pack ice and in continental waters, often in very large flocks. Prions have suffered from predation by introduced cats and rats. Removal of these may eventually lead to population recoveries.

Storm petrels are the smallest and lightest seabirds in the world. The Wilson’s storm petrel (Oceanites oceanicus) weighs only 35g to 45g. ‘Willies’ have a circumpolar distribution and breed on the more southerly sub-Antarctic islands, such as South Georgia, and on the Antarctic Peninsula and continent, as well as on islands near Cape Horn and in the Falklands. They have been regarded as the world’s most abundant seabird; there are certainly several million of them. They are regular ship followers and associate with whales. Medium-sized black-bellied (Fregetta tropica) and white-bellied (F. grallaria) storm petrels are closely related; they are separated by the presence or absence of a black line down the center of an otherwise white under body. White-bellies breed on the more northerly islands of the Southern Ocean. Black-bellies breed on South Georgia, Îles Crozet and Kerguelen, and on islands along the Antarctic Peninsula. The small gray-backed storm petrel (Garrodia nereis) is distinctively marked with white underparts, a dark-brown head and back and a gray rump. Gray-backs have a discontinuous distribution in the Southern Ocean, with three centers near breeding localities in the South Atlantic Ocean, southern Indian Ocean and south of Australasia.

Other petrels that might be spied include the blue petrel (Halobaena caerulea), superficially resembling prions, but for the white terminal band to the tail, which breeds at Islas Diego Ramirez, South Georgia, the Prince Edward Islands, Îles Crozet and Kerguelen, and Heard and Macquarie Islands, and has an at-sea circumpolar distribution; the cape petrel (Daption capense), whose speckled dark brownish-black-and-white appearance gives it its other common name, ‘pintado,’ meaning ‘painted’ in Spanish, and which has a wide, circumpolar at-sea distribution and a wide breeding range, from the Antarctic continent to the more southerly sub-Antarctic islands; the South Georgian diving petrel (Pelecanoides georgicus), which breeds at South Georgia, and on islands in the southern Indian Ocean and off New Zealand; the common diving petrel (P. urinatrix), which breeds at a number of southern islands, from South Georgia to the Tristan da Cunha group and south of New Zealand; and the white-chinned petrel (Procellaria aequinoctialis), which breeds at the Falkland Islands, South Georgia, Prince Edward Islands, Îles Crozet and Kerguelen and on New Zealand’s sub-Antarctic islands, and has an at-sea distribution that is circumpolar, with a wide latitudinal range.

Other Birds

Cormorants

There is not yet firm agreement on how many species of cormorants (Phalacrocorax spp.) – or shags, which is their other commonly used name – inhabit the southern islands and the Antarctica Peninsula. There are probably as many as seven, or as few as two, depending on what taxonomic levels are used. All are reasonably similar; they are brown-black with long necks and wing plumage, and they have a distinctive fast-flapping flight.

Cormorants breed on the Antarctic Peninsula, on all the sub-Antarctic islands and on the islands south of New Zealand. They breed in summer, making nests of seaweed and terrestrial vegetation in colonies on cliff tops and ledges directly above the sea. Cormorants eat mainly benthic fish, caught by deep and long dives from the surface (rather than by plunging from a height above the water).

Kelp Gulls

The kelp, or Dominican, gull (Larus dominicanus) is the only gull of the Southern Ocean. It lives on the Antarctic Peninsula and at most sub-Antarctic islands, where it is resident year-round, generally in small numbers. Like most southern seabirds, kelp gulls breed in summer.

Diet includes scraps scavenged from penguin colonies and giant petrel kills, terrestrial invertebrates such as earthworms and moth larvae, and intertidal shellfish such as limpets.

Sheathbills

Sheathbills are not seabirds (their feet are not webbed) but are in their own family, and allied to waders or shorebirds. They are Antarctica’s only land-based bird, and they often strut and squabble around penguin colonies. The greater sheathbill (Chionis alba) – also known by the names American, snowy or pink-faced sheathbill – is found at South Georgia, the South Shetland and South Orkney Islands and along the Antarctic Peninsula; they migrate north to South America and the Falklands in winter. They have a thick, white plumage and sturdy bodies. Lesser or black-faced sheathbills (C. minor) are somewhat smaller, with noticeably shorter wings. They are strict residents of the four sub-Antarctic island groups of the southern Indian Ocean, each with its own subspecies.

Sheathbills nest in crevices in summer, usually near penguin colonies, where they scavenge eggs, spilled food being fed to chicks, and from carcasses killed by giant petrels. They also feed on intertidal life and on invertebrates in the peat.

Skuas

Skuas are large, heavily built gull-like birds, that are mainly brown but with conspicuous white flashes in their wings. South Polar skuas (Catharacta maccormicki) are marginally smaller than sub-Antarctic or brown skuas (C. antarctica) and have a paler plumage.

Sub-Antarctic skuas breed on most of the southern islands, whereas South Polars are found on the Antarctic continent. On the Antarctic Peninsula, both species occur, and hybrid pairs are regularly recorded.

Both species breed in summer, generally laying two mottled eggs in open nests on the ground. Skuas are aggressive hunters and prey upon the eggs and chicks of penguins and other colonial seabirds (including adults of smaller species), and feed on carrion. They also consume Antarctic krill, squid and fish.

In winter, both species leave their breeding areas and spend time at sea, occasionally reaching the northern hemisphere.

Terns

Several species of tern (Sterna spp.) may be seen in the Southern Ocean. The Antarctic (S. vittata) and the rarer Kerguelen (S. virgata) terns breed at a number of southern islands. The former are more widespread and occur on the Antarctic Peninsula as well. At sea you’ll likely see Arctic terns (S. paradisaea), long-distance migrants from the northern hemisphere. Kerguelens are resident on the few islands where they occur, whereas Antarctic terns migrate, several thousand reaching South African waters to spend the winter.

All three species are slender, long-winged gray-and-white birds, similar in size. Arctic terns have white foreheads and dark bills; the Antarctic and Kerguelen species are red-billed and have conspicuous black caps.

Antarctic and Kerguelen terns breed in summer, laying mottled eggs in open nests on the ground in loose colonies. They eat mainly small fish caught at the surface or by shallow dives within sight of land, often within the kelp-bed zone. The rare Kerguelen tern is considered 'near threatened' and both breeding species are at risk from feral cats on islands where felines occur.

Shearwaters

The great shearwater (Puffinus gravis), with its dark cap and white band at the base of the upper tail, breeds only in the Tristan da Cunha group and Gough Island (except for a very few in the Falklands). The black-and-white little shearwater (Puffinus assimilis) is often seen in groups of two or three, usually close to breeding localities – the Tristan da Cunha group, Gough Island, Île St Paul and islands around Australia and New Zealand. It has a circumpolar at-sea distribution in the Southern Ocean. The sooty shearwater (Puffinus griseus) is all brown, apart from its silvery underwings. It has a circumpolar at-sea distribution, and breeds on islands off New Zealand and Cape Horn.

Fish & Benthic Species

The Southern Ocean supports more than 270 species of fish and the nutrient-rich area just north of the Antarctic Circumpolar Current gives rise to some of the world’s most productive fisheries. Some of the species nearest the continent or on the ocean floor (benthic region) are very different from those of other oceans.

Scientists study several fascinating species such as the Antarctic cod or toothfish (Dissostichus mawsoni), which survive in subzero waters without freezing because of ‘antifreeze’ proteins in their blood. Antarctic cod are not related to other ‘cod’ and can grow to 2m and 135kg. Their hearts beat only once every six seconds.

Members of the ice fish family Channichthyidae, such as the mackerel ice fish (Champsocephalus gunnari), have no hemoglobin and are ‘white-blooded.’ Oxygen is carried in their blood plasma, but this has only 10% of the oxygen-carrying capacity of fish blood containing hemoglobin. To make up for this, ice fish have more blood, a larger heart, larger blood vessels and more gill surface area, and can even exchange oxygen through their tails.

All Antarctic fish grow slowly, with most coastal species requiring five to seven years before they can breed. This is of great importance when deciding sustainable catch limits. Due to initially uncontrolled fishing, several species, including the marbled notothon (Notothenia rossii) and mackerel ice fish, are now commercially extinct. Fisheries have targeted new species, such as the Patagonian toothfish (Dissostichus eleginoides), and CCAMLR attempts to control practices with a system of annual quotas and inspections. Nevertheless, overfishing remains a threat.

The communities that inhabit the seafloor around Antarctica are called the benthos, and are as rich in plants and animals as a tropical coral reef. They comprise Antarctica’s true indigenous flora and fauna, adapted to life in a cold ocean over tens of millions of years (such as Turquet’s octopus, Pareledone turqueti). Nearly every time a deep-sea sample is brought up, it includes many species new to science.

Invertebrates

Antarctic Krill

Antarctic krill (Euphausia superba) is a 6cm-long planktonic crustacean that is found in sometimes-enormous swarms south of the Antarctic Convergence. There is also a smaller species, the ice krill (E. crystallarophias). Krill is sifted out of the water by baleen whales, and eaten by many species of southern seabirds (especially penguins), squid, fish and crabeater seals. Without krill the ecosystem of the Southern Ocean would collapse.

Antarctic krill has been the target of fisheries, and quotas are now set by CCAMLR, which also encourages research on krill and its predators.

Terrestrial Invertebrates

Antarctica’s native land animals are all tiny invertebrates, many of them specially adapted. They include mites, lice, springtails, midges and fleas, many of which are parasites of seals and birds. Some mites, however, inhabit exposed soil and survive extreme cold and dryness. Studies on the continent have concentrated on the microbiota: ciliates, rotifers, tardigrades and nematodes.

Introduced invertebrates such as slugs, snails, earthworms, spiders, isopods and aphids arrived on sub-Antarctic islands, some changing the ecosystem.

Plants & Algae

Antarctic plant species are more numerous than you would expect, but they are far smaller and less conspicuous than plants in other latitudes. Antarctica is home to nearly 400 species of lichen, 100 species of moss and liverworts, and hundreds of species of algae – including 20 species of snow algae.

Terrestrial Plants

Antarctica’s plants differ greatly from those found on sub-Antarctic islands. The continent supports only mosses, lichens and algae, along with two flowering plants, a hairgrass (Deschampsia antarctica) and a cushion plant or pearlwort (Colobanthus quitensis), which have footholds on the comparatively milder Antarctic Peninsula. Interestingly, global warming is believed to be the cause for the observed spread of this grass.

Very large specimens of lichens (some more than 500 years old) and banks of moss more than 1m deep can be found, especially on the Peninsula. Radiocarbon dating shows the base of large moss banks to be as much as 7000 years old.

High rainfall and long hours of summer sunshine allow the islands to support diverse and at-times lush vegetation (epitomized by tussock grassland). South Georgia alone boasts at least 50 species of vascular plants – but no trees. The more northerly cool temperate islands, such as Tristan da Cunha and Gough, support a few native trees.

Marine Plants

The intertidal and subtidal areas of the southern islands support giant seaweeds such as bull kelp (Durvillea antarctica), which form thick bands and protect shores from rough seas. These kelp ‘forests’ support fish, shellfish, octopus and crustaceans, which in turn provide food for inshore-foraging birds, such as cormorants and terns.

There are more than 100 species of plankton in the Southern Ocean. The productivity of all Antarctic ecosystems rests on the photosynthesis of the phytoplankton group, which are tiny single-celled plants or microscopic algae, floating in the upper layers of the Southern Ocean. Ice algae stains pack ice pink or brown, and snow algae grows atop certain areas of snow. During algal blooms, the sheer density of phytoplankton is so great that they color the ocean.

Feature: Rock Algae

In areas formed from large-grained sandstone (Victoria Land) the outer skin of the rocks themselves has been colonized by plants. These plants live within the rock, growing between the sand grains and forming separate layers of algae, fungus and lichen. Just enough light penetrates for photosynthesis to occur for a short period each year (sometimes only a few days) when meltwater is available. Acids excreted by the plants eventually dissolve the rock and the outer skin breaks off. The growth rate of these plants is so slow that some may be many thousands of years old.

Threats to Antarctic Wildlife

Antarctica’s exploration was tied directly to the exploitation of its marine mammals, specifically seals and whales.

Nowadays, many of the threats to Antarctic wildlife come from ecosystem changes, such as those caused by global warming.

The Past

Whales

Antarctic whaling was established in 1904, with 183 whales killed the first season. By 1912–13, six land stations, 21 factory ships and 62 catcher boats killed and processed 10,760 whales. South Georgia was an important early catching ground. By the 1920s, advancing technology (particularly the stern slipway, which allowed the entire whale to be winched aboard a floating factory ship for processing) shifted predominance to pelagic, or open-ocean, whaling. Also, since they were at sea, pelagic factory ships avoided government limits on whale-hunting. By 1930–31 the annual kill had increased to 40,000. With the exception of the years during WWII, whaling continued at this level for the next 20 years. As each targeted species was driven to near extinction whalers switched to a new species.

The International Whaling Commission (IWC; www.iwc.int) was established in 1946 to regulate the ‘orderly development of the whaling industry’ worldwide. It agreed to a moratorium, which came into force in 1986, on all commercial catches.

Seals

Nearly a third of the peri-Antarctic islands were discovered by sealers. Sealers often preceded explorers, thus becoming explorers themselves. The sealing trade was aggressive. The South Shetlands were discovered in 1819, and by 1823–24 fur sealing there was already over, due to the rapid influx of sealers and the near-extinction of the seals.

Fur seals were hunted for their thick pelts and elephant seals for their blubber, which could be rendered into oil.

Finfish & Krill

In the 1970s, fish (called finfish to distinguish them from shellfish) became commercially targeted. Species in the South Georgia area (Antarctic cod, ice fish) were caught in great numbers, mostly by the Soviet Union. Commercial extinction followed, from which these species have never recovered.

Simultaneously, world interest turned to krill (fished commercially since 1972). The catch reached a peak in the early 1980s at more than 400,000 tonnes per summer season. At first it was postulated that in their vast numbers, krill might solve the world’s famine problems. However, although relatively easy to catch once a swarm has been identified, krill have proved costly to process and difficult to market. Krill possess some of the most powerful protein-digesting enzymes ever found, so they must be processed very rapidly or their tissues begin to break down, turning black and mushy. They become unfit for human consumption after three hours on deck and unfit for cattle feed after 10 hours. Krill also have high levels of fluorine in their outer shell, making them toxic unless the shell is completely removed.

Modern Era

Whales

In modern times, the IWC moratorium on commercial catches has come under pressure from whaling nations such as Japan and Norway.

In 1994 the IWC established the Southern Ocean Whaling Sanctuary to protect the primary feeding grounds of the majority of great whales and to provide an opportunity for depleted species to recover. The sanctuary does not allow commercial whaling, even if the worldwide moratorium were to be lifted. However, there is an exception for whaling for scientific purposes.

Seals

Seals are officially protected on land and ice shelves, where they can only be killed for scientific purposes (permit required). The Convention for the Conservation of Antarctic Seals extends this protection to the sea, the sea ice and the pack ice. It prohibits the commercial culling of fur, elephant and Ross seals and establishes closed areas and closed seasons for the other species.

Since the convention maintains catch limits for crabeater (175,000), leopard (12,000) and Weddell seals (5000), in theory commercial sealing could occur again; but the public outcry it would generate makes this unlikely.

Finfish & Krill

Fish and squid are caught in large numbers; around South Georgia, crabs are taken, too. The CCAMLR, which came into effect in 1982, placed limits on fishing, unless data showed that catches could be increased, taking into account the whole ecosystem. Inspection and scientific-observer schemes were put in place. With increased monitoring, however, there also came an increase in fisheries trying to work outside the law.

The 1990s saw a rush on Patagonian toothfish or Chilean sea bass (Dissostichus eleginoides). Due to its late sexual maturity, the toothfish is highly vulnerable to overfishing; additionally, longline fishing, which is used to catch them, causes the death of albatrosses and petrels. The Patagonian toothfish can grow to more than 240cm and 130kg, though most caught today weigh less than 10kg. CCAMLR reacted with a Catch Certification Scheme and Dissostichus Catch Documentation requirements. Individual countries tried to take action when illegal fishing took place within their exclusive economic zone. Nevertheless, since 1996 illegal fishing has exceeded legal fishing of toothfish.

In spite of CCAMLR’s efforts and a consumer boycott called for by environmentalists, toothfish is in danger of being fished (legally and illegally) to commercial extinction. In the UK, toothfish is known as Antarctic sea bass, Australian sea bass or Antarctic ice fish.

Antarctic krill is canned or frozen and sold as ‘Antarctic shrimp,’ and also used as cattle and fish feed and in aquaculture. Advances in fishing technology coupled with growing interest in krill for nutriceutical uses may have contributed to recent rises in krill catches: 109,000 tonnes were caught in the 2006–07 season; 210,000 tonnes in 2010–11 and 294,000 in 2014. Despite being well below CCAMLR limits, there is concern that the fisheries should be monitored and that krill (the base of the Southern Ocean food chain) are also facing pressure from climate change.

Sidebar: Giant Squid

A rarely-seen colossal squid caught in the Ross Sea by a New Zealand fishing boat in 2007 was 10m long and weighed nearly 500kg. Its two basketball-sized eyes, each measuring 27cm across, are the largest known eyes.

Sidebar: Obscure Species

The largest animal that permanently dwells on Antarctica is a wingless midge (Belgica antarctica) that grows to just over 1cm long. New Antarctic species are being discovered continuously: in 2012, 23 new animal species were identified around Antarctica’s underwater hydrothermal vents.

Sidebar: Sperm Whales & Giant Squid

Sperm whales have powerful sonar and can dive to 3200m, remaining submerged for over an hour hunting prey including giant squid. Scientists calculate the size of squid eaten by whales, seals and seabirds by measuring the squid’s indigestible beaks (mouth parts) when they are regurgitated, and then extrapolating.

Sidebar: Whale Sounds

Blue whales are the loudest animals on Earth. They can emit low-frequency sounds that are louder than 180 decibels and can travel thousands of kilometers. Humpback whales are highly vocal in their breeding grounds: songs of up to 20 minutes are thought to be mainly produced by adult males.

Sidebar: Fur Seals

Fur seals, related to sea lions, can walk on all fours; and about one in 800 is of the ‘blonde’ variety, with markedly yellow- or cream-colored fur.

Sidebar: Elephant Seals

Elephant seals have huge reservoirs of blood (22% of their body mass) and can slow their hearts to just a single beat per minute. The deepest dive recorded is an amazing 1930m; they can stay down for two hours, and rest for surprisingly short intervals at the surface.

Sidebar: Remote Sensors

Animals, especially seals and penguins, are becoming gatherers of data using remote sensors. Elephant seals dive under ice in winter, to depths over 900m, situations difficult for humans to duplicate. Small sensors attached to an animal's body can transmit data to a satellite when it resurfaces.

Sidebar: Deep Diving Penguins

Emperor penguins eat fish, krill and squid, and capture their prey by pursuit-diving, often to amazing depths and durations: as much as 535m and 22 minutes, by far the deepest and longest dives known for any bird.

Sidebar: Leucistic Penguins

Leucistic (or albinistic) penguins have whitish-beige, not black, plumage due to a genetic inability to produce melanin. Scientists estimate leucism rates on the Antarctic Peninsula at about 1:114,000 in Adélies, 1:146,000 in chinstraps and 1:20,000 in gentoos.

Sidebar: Great Albatross

The genus name Diomedea of the 'great’ albatross commemorates the Trojan hero Diomedes, whose companions were turned into large, white birds by the Greek gods.

Sidebar: Flight of the Albatross

Gray-headed albatrosses breed every second year. On their year off, they can fly right around the Southern Ocean, with some making journeys as long as 12,000km.

Sidebar: Petrel Mumiyo

Snow petrels can regurgitate their stomach oil as a defense mechanism. Deposits of this substance, called mumiyo, have built up around nest sites over thousands of years and can be radiocarbon dated. The oldest-known colony dates back an astounding 34,000 years.

Sidebar: Skua Strategies

At sea, skuas chase smaller seabirds to force them to regurgitate or drop their prey (an act known as kleptoparasitism), often retrieving it spectacularly before it drops to the water.

Sidebar: Dogs in Antarctica

Dogs were once widely used in Antarctica to pull sledges, but they were banned from the continent by the Antarctic Treaty’s Protocol on Environmental Protection. The last were removed in 1994.

Sidebar: Kerguelen Cabbage

Kerguelen cabbage (Pringlea antiscorbutica), found on southern Indian Ocean islands, was used by shipwrecked 19th-century sealers to ward off scurvy (as its scientific name suggests).

Sidebar: Historic Whale Catches

For an idea of the numbers of whales caught, we can look to records from South Georgia, the main site of land-based operations. From 1904 to 1965, when whaling at South Georgia ceased, a total of 41,515 blue whales were caught, along with 87,555 fins, 26,754 humpbacks, 15,128 seis and 3716 sperm whales.

Sidebar: Whale Oil

Historically, whale oil was used for lighting, lubrication and tanning; in the early years, it was mainly a Norwegian and British industry.

Sidebar: Orcas – Apex Predators

The only natural predator of leopard seals are orca whales.

Sidebar: Wildlife Reads

  • Complete Guide to Antarctic Wildlife (2008), Hadoram Shirihai
  • The National Audubon Guide to Marine Mammals of the World (2002), RR Reeves
  • Albatrosses and Petrels Across the World (2004), Mike Brooke
  • Antarctic Underwater Field Guide (www.oikonos.org/apfieldguide), David Cothran

Antarctic Science

Since its earliest exploration, Antarctica has been a land of discovery. Many of the initial expeditions were undertaken to discover whether the fabled Terra Australis Incognita existed, and then, once it had been identified, to determine its extent, properties, flora and fauna. In the modern era, with the creation of the Antarctic Treaty, Antarctica became the one protected continent in the world, reserved almost exclusively for scientific research.

A Global Approach

Two key features of Antarctic science are that research findings are freely available to everyone and that many of the projects are internationally supported. This coordination has been arranged since 1957 through the Scientific Committee on Antarctic Research (SCAR; www.scar.org). More recently, information is being centrally gathered by Polar Information Commons (www.polarcommons.org).

As it turns out, Antarctica offers not only myriad opportunities to study a unique environment with specially adapted life forms, but it sits at the center of some of the great scientific questions of the modern age. The region is particularly vulnerable to the effects of climate change, as well as being a source of weather and global patterns that affect the entire world, and also a superior place from which to monitor changes. Despite Antarctica's remoteness, much of the research done there is immediately relevant to Earth's populated areas.

The International Geophysical Year 1957–58 really kicked off modern Antarctic science, and the International Polar Year 2007–08 (IPY; www.ipy.org), the coordinated international science program, helped push polar science to the next level and integrate it more closely into our models of how the Earth works.

Feature: Polar Programs

International Bodies

Council of Managers of National Antarctic Programs (COMNAP) www.comnap.aq; offers full list of bases and programs, plus interactive map.

Scientific Committee on Antarctic Research (SCAR) www.scar.org

International Polar Year 2007–08 www.ipy.org

European Polar Board www.europeanpolarboard.org

Polar Information Commons www.polarcommons.org

National Programs

Australia www.antarctica.gov.au

Britain www.bas.ac.uk

Chile www.inach.cl

China www.chinare.gov.cn

France www.institut-polaire.fr

Germany www.awi.de

India www.ncaor.gov.in

Japan www.nipr.ac.jp

New Zealand www.antarcticanz.govt.nz

Norway www.npolar.no

Russia www.aari.aq

South Africa www.sanap.ac.za

USA www.usap.gov, www.nsf.gov

Fields of Study

Many of the questions that stand to be answered by research in Antarctica are of a multidisciplinary nature and involve linked, complex systems. For example, how does climate change affect winds and atmospheric, land and ocean temperatures; how do they then interact with ice shelves and sheets; and how do they, in turn, affect sea level and, potentially, global climate? Therefore, many of the fields of study listed here are linked with other fields, both conceptually and in their information gathering. Cores taken of ice and land and ocean sediment, for example, are used across many disciplines, and by many nations.

Feature: Humans

It's not just the animals that scientists study. Research on humans stationed in Antarctica include studying the effects of the seasonal changes in the climate and UV light, the isolation experienced during winter, epidemiology, and the effects of diet and exercise on health.

Ecosystems

Antarctic ecosystems are, relatively speaking, simpler than those in other parts of the world. Thus it is easier to observe changes in the systems due to factors such as global warming. Though Antarctic life evolved separately, starting with the opening of the Drake Passage millions of years ago, issues such as pollution, increased UV radiation and climate change are impacting species and ecosystems, thus providing dynamic areas of study. Disciplines include biochemistry, biology, physiology, genomics and evolution.

Since the 1990s, for example, studies such as the Palmer Station (http://pal.lternet.edu) and McMurdo Dry Valleys (www.mcmlter.org) Long Term Ecological Research (LTER) projects have been recording data on these interactions, and are trying to answer the question: how will these ecosystems interact and alter in the face of increasing changes in the region?

Marine Life

Marine animal populations are being monitored both through direct counting, tagging individual animals, and, more recently, through satellite observations. For example, in 2012 satellite data revealed more than twice as many emperor penguins exist than were previously estimated (595,000 as opposed to 270,000); the first complete census of a species taken from space.

The use of satellite transmitters and other electronic equipment provides remarkable marine-life data: for example, while at sea, elephant seals spend almost 90% of the time submerged, making dives of up to two hours' duration and reaching depths of more than 975m. How they manage this is the subject of wide-ranging physiological research. Similarly, a tiny satellite transmitter on a bird's back can report on its position, while a small tube on its leg can collect data on the depth and timing of its dives for food. Even the oxygen consumption required for flying or swimming can be measured automatically.

Evolved characteristics for study include body shape and composition, cardiovascular control, body temperature, metabolism, oxygen levels when deep diving and resurfacing (without getting the bends), prey availability, and adaptations to the rhythm of sea-ice formation and retreat.

The Census of Antarctic Marine Life (CAML; www.caml.aq), with its 17 ships and scientists from 20 nations, investigated the population numbers and distribution of Antarctic marine life. This study required expensive infrastructure – icebreaker research vessels, scuba-diving facilities, laboratories at research stations and access to satellite data – promoting international research in which resources are shared.

A great deal of research has been undertaken to establish the diversity, life histories and extent of fish stocks. Most research has concentrated on the two most abundant groups – the Antarctic cod (Nototheniidae) and the ice fish (Channichthyidae) – with interest focused on the evolution of the groups, their ability to survive in icy waters, their reproduction and growth rates, and their population age structure.

Every aspect of the life cycle and biology of krill, the single most important food of whales, seals and birds, has been studied.

Phytoplankton or algae contain chlorophyll, which can be detected by satellite. Plankton takes up carbon from carbon dioxide dissolved in the water, and when it dies takes the carbon down into the sediments. This has prompted considerable research on how much carbon can be taken out of the atmosphere by phytoplankton and what, if anything, can be done to increase the rate. Studies on the effects on phytoplankton of increases in springtime UV radiation continue.

The communities that inhabit the seafloor around Antarctica are called the benthos, and are as rich in plants and animals as a tropical coral reef. Research focuses on identification and the biochemistry and physiology of benthos.

In short, scientists study everything from breeding behavior and rates of growth to diet and the impact of climate change.

Terrestrial Life

The relationships between Antarctic plants and those on the surrounding continents have interested botanists for almost 160 years. Research continues on how these lichens and mosses survive bizarre terrains and the extreme cold and desiccation of the Antarctic winter.

Invertebrates such as mites and nematodes are also the subject of much research, in part because of how they survive extreme cold (many make antifreezes), a lack of water and oxygen (some put their metabolism into a special state), and high salt levels in the soil.

There is increasing interest in how microbial communities survive in Antarctica. Where retreating glaciers reveal bare rock and soil, scientists use new technologies to both investigate the earliest stages of the colonization of these areas and to develop a better understanding of how complex communities develop. For example, in 2009 bacteria were discovered under an inland glacier with no light or heat and very little oxygen (they convert iron compounds for energy). In 2012 a new technology called SkyTEM (www.skytem.com) allowed the mapping of subsurface groundwater and rock, giving a view into under-ice microbial systems in the Dry Valleys that were previously inaccessible.

A joint IPY program studied alien plant and invertebrate species carried to Antarctica and their effects on native ecosystems.

Lakes & Streams

Within the many ponds and lakes scattered around ice-free areas (some very saline, some that have almost no nutrients), the most developed animal is a small shrimp and the most complex plant is an aquatic moss. Many lakes are dominated by microbial communities. The simplicity of the systems attracts scientists: work has concentrated on the lakes in the Taylor and Wright Valleys (especially Lake Vanda), at the Vestfold and Bunger Hills regions, and at Signy Island. Additionally, the sediment at the bottom of lakes contains a record of how the lake has changed over a period as long as 10,000 years; this helps in determining the history of Antarctica's recent climate.

Subglacial Lakes

One of the areas of extreme interest and debate now is the drilling into subglacial lakes such as enormous Lake Vostok. This lake, which had been untouched for 200 million years, was tapped in 2012 by Russian scientists.

Geology, Geomorphology & Paleontology

Less than 0.5% of Antarctica's rock is accessible for direct examination. Some scientists say that the geology and topography under the ice (especially in East Antarctica) are less well known than the topography of Mars. In fact, the Dry Valleys are the best terrestrial analogue for Mars, and study there has possible applications for life under extraterrestrial frozen seas.

Understanding the connections between the southern continents, and how they broke apart and why, continues to fascinate geoscientists, as do the origins of the subglacial mountains, such as the Gamburtsev range, which lies under Dome A. In 2012, new data-gathering techniques revealed a previously unknown extension of the East Antarctic Rift System (a fracture that extends 2500km from India to Antarctica).

Antarctica's glacial and tectonic histories are interlinked, as without the high topography the ice sheet would have formed quite differently. Geomorphologists study Antarctic landforms and have mainly been concerned with the effects of the ice sheet on the underlying rock, as well as the study of glacial deposits, the remains of old beaches left when the sea level fell, and the formation of patterned ground.

Technology is developing to better observe these systems, and further study will be accomplished with airborne radar, long-range aircraft, laser observation, gravity and magnetic field data, and a new generation of clean, rapid drilling systems (for ice and sediment cores).

Feature: Ice Cores: Drilling into the Past

As snow is deposited on the surface of the Antarctic ice sheet, different chemicals and gases that have dissolved and mixed in the snow and in the atmosphere become trapped in the ice. By drilling through the ice sheet and analyzing the ice and air trapped in the bubbles, glaciologists access an archive of past climate change, both locally and globally. Drilling is a difficult and highly skilled activity, often extending over years. The ice sheet is always moving, so the drill hole is continually being bent and squeezed shut unless it is kept open with drilling fluid.

The oxygen isotope ratio (or 'delta value') of melted ice samples is related to the temperature when the ice was deposited as snow. Thus, a climate history can be built up by measuring delta value from the surface of the ice sheet down. At Russia's Vostok Station, an ice core was drilled to a depth of 3623m. The ice at the bottom of this core is about 426,000 years old, and the delta values show several glacial cycles; that is, several ice ages and warmer interglacial periods. The oldest ice core (3km deep) came from Dome C: 800,000 years old. They could get even older: the oldest ice estimate is about 1.5 million years, in the East Antarctic interior.

Air pockets between snow grains on the surface of the ice sheet become bubbles under high pressure deep down in the ice. These bubbles contain tiny samples of the atmosphere from earlier times. Analysis of the air trapped in the bubbles allows glaciologists to examine how the concentrations of different gases in the atmosphere have changed over time.

While some ice cores (such as Vostok's) give a climate history extending back hundreds of thousands of years, they cannot be dated accurately. Other cores, drilled at locations where the snow accumulation is relatively high, can provide very precise dating if the annual snow layer is thick enough, because several samples can be analyzed for each year of snow. This ice is (comparatively) not that deep, so data is for the past few thousand years.

Ice cores can be dated by counting annual layers (cycles of hydrogen peroxide); dating decay rates of natural isotopes; modeling changes in ice flow with age; and by their sulfate levels. Sulfate is blasted into the atmosphere by erupting volcanoes and is then distributed around the globe. By measuring sulfate concentration in the ice cores, glaciologists can 'see' past volcanic eruptions. By collaborating with volcanologists, they can then determine which sulfate signals in the ice correspond with which volcanic eruption and when that eruption occurred. They can also study world pollution.

For the world's ice core and climate data, visit www.ncdc.noaa.gov. There are three ice core programs: West Antarctic Ice Sheet Divide Ice Core (WAIS Divide; www.waisdivide.unh.edu), Dome Fuji Ice Core (www.ncdc.noaa.gov) and Epica (European Program for Ice Coring in Antarctica; www.esf.org).

Credit

Dr Jo Jacka

Bio

Written by Dr Jo Jacka, Glaciologist and Palaeoclimatologist

Seismology & Volcanology

The Polar Earth Observing Network (Polenet; www.polenet.org) seismic array was completed in 2012, placing sensors over about one-third of Antarctica. These sensors record seismic activity, giving insight into geological makeup, and offer GPS monitoring to the millimeter of bedrock uplift, for use in calculating changes in the ice sheets.

The South Pole Remote Earth Science and Seismological Observatory detects earthquakes worldwide, while the Mt Erebus Volcano Observatory (http://erebus.nmt.edu) studies the active volcano.

Minerals & Soils

Are there vast deposits of precious metals and ores beneath the Antarctic ice sheet? Are there huge basins of gas and oil under the Weddell and Ross Seas? Antarctic geologists are working to determine how known mineral deposits were formed and what they can tell us about geological processes.

Antarctic soils are primitive, almost without organic matter, very dry, and with a high salt content. Scientists working on soils in the Dry Valleys have been able to show that some of them are at least five million years old, giving a possible date for the retreat of ice from these valleys.

Fossils

Fossils give us evidence of ancient life in Antarctica. Coal beds and plant fossils in the Transantarctic Mountains were reported by both Ernest Shackleton and Captain Robert Scott, clearly indicating that the Antarctic was not always covered with ice. Since then much more fossil evidence of preglacial periods has been uncovered. Antarctica even had dinosaurs.

Fossils provide evidence of the connections between the parts of the ancient supercontinent Gondwana, give indirect information about the changes in Antarctic climate over millions of years, and offer an insight into the evolution of present Antarctic species.

Many deposits contain fossil plants, petrified wood (sometimes in pieces as long as 20m) and fossil pollen, but fossils of animals are much less common. In some places ferns and other woodland species are also preserved in great detail.

Meteorites

Most of humankind's knowledge about meteorites comes from analysis of those found in Antarctica, which acts as a huge meteorite collector.

Ice & the Southern Ocean

The study of Antarctica's ice sheets, shelves and sea ice is critical to understanding climate change, sea-level rises and the interactions of myriad inter-related systems.

When Antarctica's ice shelves are lost along the continent's edges, continental ice moves more rapidly toward the sea. Studies from 2002, 2012 and 2016 show that a major contributor to this loss is warming ocean temperatures, which undermine ice shelves from subsurface cavities. Additionally, increasing winds are predicted to increase ocean upwelling rates, which would also increase subglacial melting.

Currently, there are many questions facing scientists regarding Antarctic ice, oceans and climate change. For instance, summer temperatures on the major ice sheets remain below freezing, so how will the ice sheet respond to rapid temperature changes? And what are the interactions between sea, land and atmospheric temperatures, winds, ice shelves and sheets, ocean salinity and acidity, ocean circulation, bottom waters, and carbon uptake?

Understanding the processes around the stormy waters of the Southern Ocean is also critical for understanding the world's systems. Southern Ocean circulation is central to global ocean circulation, and it is the site of upwelling to the surface of deep water from all oceans. Scientists study these processes and the effects of Antarctic bottom water.

Cold waters can absorb more of the excess carbon dioxide generated by humankind. Plus, fresh water from ice melt is 10 times more acidic than sea water. Increases in carbon dioxide in Antarctica's waters reduce the calcium carbonate that many marine organisms need for bone or shell, raising significant questions. Will organisms adapt? Migrate? Where will they be able to find cold temperatures? The international Census of Antarctic Marine Life studied the Southern Ocean, shedding light on these issues.

As part of the World Ocean Circulation Experiment, which measured worldwide current patterns in order to improve existing computer models for predicting climate change, several countries placed current meters on the seafloor around Antarctica. A network of tidal gauges, which often report data via satellite, has also been installed at various Antarctic stations.

Glaciers & Floating Ice Shelves

We now have enough historical data to study changes in glaciers over decades. Assessing 244 glaciers around the Antarctic Peninsula has shown that 87% have retreated over the past 50 years, and over 300 glaciers show an increased rate of flow into the sea. Satellite data also allows glaciologists to monitor giant icebergs calving.

Other research on the ice shelves concentrates on determining how quickly ice is moving off the continent, and how rapidly the shelf ice thins from the melting of its underside.

The long-term objective is to provide researchers with a computer model that will allow the loss of ice to the Southern Ocean to be accurately predicted and combined with other climate and ocean models. Investigating the underside of the ice shelves is now possible using remotely operated vehicles (ROVs).

Sea Ice

Antarctic sea-ice cover varies from a minimum of 4 million sq km in February to a maximum of 20 million sq km in September, and this huge seasonal change has enormous repercussions. The ice alters the exchange of heat, ocean and atmospheric circulation, and the marine ecosystem has to adapt to lower temperatures and a lack of light under the ice. Developing models of the way sea ice effects energy transfers between the sea and air is a major scientific concern.

Satellite observation of the sea ice began in 1979, and now the Sea Ice Mass Balance in the Antarctic project (Simba; http://utsa.edu/lrsg/Antarctica/SIMBA) uses radar and altimetry data to set a baseline for future measurements, which can help answer the question: how does all of this interact with the climate?

To verify satellite data, research must be undertaken inside the pack ice; technologies include drifting buoys, which will give meteorological and oceanographic data and more information about ice movement.

Climatology & Weather Forecasting

Antarctica and the Southern Ocean are directly connected to the entire global climate system – atmosphere, global ocean circulation and overturning, and the rate of carbon dioxide uptake. To understand the world's system, we must understand Antarctica and the Southern Ocean. Furthermore, climate, glacial ice, sea ice and the ocean are all interconnected.

Using this understanding of interconnectedness, scientists reconstruct past climate conditions (paleoclimatology) to understand the present and to model predictions for the future. This is all accomplished through sediment drilling, studying ice cores and fossil records, and understanding changes in the Earth's orbit and greenhouse gases.

Countries surrounding the Southern Ocean have a great interest in the current meteorology of Antarctica. The strong westerly winds and their associated weather systems drive storms across the Southern Ocean and beyond, while the seasonal formation and melting of sea ice has a major effect on southern-hemisphere weather. Antarctic bases and automated weather stations share daily meteorological observations; over 100 locations represent 12 nations.

Atmospheric Science

Global warming and ozone depletion have made the study of atmospheric gases a major Antarctic discipline. Observations made from satellites, drones, constant-level balloons and self-sustaining blimps also have applications for other disciplines.

Atmospheric Chemistry & Ozone Depletion

Probably the most famous science project ever undertaken in Antarctica is the monitoring of stratospheric ozone at Britain's Halley Station. A paper published in Nature in 1985 provided such alarming evidence of the increasing rate of ozone destruction that it resulted in a worldwide agreement to ban chlorofluorocarbons (CFCs). It also stimulated a massive increase in research on polar chemistry.

Greenhouse Gases & Global Warming

To measure global changes in greenhouse gases such as carbon dioxide and methane, you need a site as far away from the industries that produce these gases as possible. Thus the US chose the South Pole for carbon-dioxide measurements in 1956. This series of measurements is still running and is one of the world's most important monitoring activities, and has been expanded to other sites around the globe.

Other gases identified as important contributors to warming (nitrous oxide, hydrofluorocarbons, perfluorocarbons and sodium hexafluoride) are also rising.

Geomagnetism & Space Weather

The peculiar structure of the Earth's magnetic field over Antarctica makes it the best place in the world to investigate how the sun's activities affect the ionosphere (the north pole has no landmass, so is not suited to year-round observations). The sun produces a continuous stream of electrically charged, high-energy particles called 'solar wind.' When it comes into contact with other particles or enters a magnetic field, its energy becomes channeled and discharged. The only visible signs of this discharge are the auroras seen at both poles.

To study this, physicists use auroral radar systems looking toward the South Pole. They utilize the overlap between the beams to create a 3D picture of the changes in the ionosphere above the Pole. This data has allowed the production of 'space weather' maps, plotting the timing and duration of magnetic 'storms' that can have devastating effects on the many satellites upon which we rely.

The Space Weather Prediction Center (www.swpc.noaa.gov) and the NSF's Center for Integrated Space Weather Modeling (www.bu.edu/cism) work on these forecasts and try to monitor and understand solar cycles.

Astronomy

Incredibly stable atmospheric conditions above Antarctica's surface area (it's high, cold, dry and the thin atmosphere is transparent – there's no air or light pollution), plus its prime geographic location (objects stay in view, above the horizon), make Antarctica the best place on Earth for astronomical observations. Couple this with the very low sky noise (low wind and lack of solar heating during winter) at places such as the South Pole and East Antarctica, and it's an astronomer's dream.

Recent technological advancements have catapulted Antarctica to the cutting edge of astronomy, taking some of the most sensitive measurements ever accomplished on Earth. The South Pole is a major astronomical site with infrared telescopes (looking at star formation) and the massive South Pole Telescope.

In 2012, China installed the largest optical telescope (AST3-1) in Antarctica at their fully robotic Plato observatory at Dome A. The AST3-1 can be steered remotely, making large expanses of the night sky accessible throughout the Antarctic winter. It is the first of three telescopes that are expected to find planets around other stars and to make other observations formerly only possible from space.

A new branch of astronomy called helioseismography is making progress on the question of how the sun affects the Earth.

Searching for the Origins of the Universe

Antarctic research (specifically using the telescopes at the Pole and data from high-altitude balloons) is also playing its part in unraveling the mysteries of where the universe came from. The South Pole Telescope was designed specifically to seek the dark energy believed to comprise 95% of the universe, and to help discover the mass of neutrinos. It is used to study cosmic microwave background radiation, believed to be the remaining echo of the Big Bang. Antarctica's sensitive instruments can make measurements that show whether there is a spatial structure to the background radiation.

Similarly, IceCube investigates the mystery of the acceleration of cosmic rays to extremely high energies by detecting neutrinos, nearly massless particles with no charge, which are traceable to their direction of origin. Almost immediately after going online, IceCube provided new information – in 2012, data revealed that there were fewer neutrinos than expected for gamma-ray bursts (GRBs) if they are the source of high energy cosmic rays. This led scientists to reevaluate both their GRB and cosmic ray models.

Future of Antarctic Science

The increasing interest in developing global models to try to predict the world's future has shown Antarctica's importance very clearly. In Antarctica, the combination of direct observations and sophisticated modeling of data will lead to immense improvements in the accuracy of predictions about climate, evolution, astrophysics and more. The Southern Ocean Observing System (SOOS; www.soos.aq) became a part of the Global Ocean Observing System (www.goosocean.org) in 2011 and created a comprehensive observational instrument network monitoring the atmosphere, ice sheet, sea ice and ocean.

With scientists from over 30 countries now active in Antarctica, there is an increasing emphasis on investigating big issues that can only be tackled on a coordinated international scale. Additionally, new technologies are being developed such as DNA sequencing (which was undertaken on the Weddell seal), sensor networks, and clean sampling of subglacial lakes.

These ambitious, cooperative efforts utilize Antarctica's special features to answer scientific questions. Using the latest tools, researchers can map the Antarctic more accurately than ever before to assess the changing continent and globe. With geographic information systems, scientists can synthesize widely differing types of data to gain better understanding of how glaciology interacts with meteorology and geology, and with modern databases, all of this data can be made available to the world's scientific and educational community.

At the same time, scientists and logistics support people must continue to provide light, transportation, heat, potable water and safety while making a minimal impact on the natural environment. Ever-evolving new, clean, energy-efficient technologies will help protect and preserve the continent and its scientific riches for the future.

Sidebar: Marine Sediments

Antarctica contains one of the best climatic archives of the past. Terrestrial sediments cover the last 200,000 years and marine sediments cover millions of years. There are even older areas of ancient continental rocks. Current marine drilling projects include the International Ocean Discovery Program (www.iodp.org) and Antarctic Geologic Drilling (www.andrill.org).

Sidebar: Patterned Ground

The polygons, circles, stripes and sometimes even hummocks that can be seen throughout the Antarctic are called 'patterned ground.' They are formed by alternate freezing and thawing of water in the soil, which produces lateral sorting of coarse and fine particles.

Sidebar: Atomic Fallout in the Ice

Nuclear fallout from atomic bomb tests during the 1950s and '60s shows up clearly in ice cores drilled from the Antarctic ice sheets, and can be linked to specific events.

Sidebar: Understanding Sea Ice Changes

Currently, Antarctic sea ice increases and decreases vary by region. Contrary to General Circulation Models, Antarctic sea ice is gaining an average of 1% per decade, and scientists are homing in on why. They expect it will decrease dramatically, especially as ozone depletion's net cooling is reversed (as the hole closes).

Sidebar: Climate & Ice Modeling

Current modeling efforts include the Community Earth System Model (www.cesm.ucar.edu/working_groups/Polar) and the Community Ice Sheet Model (CISM; http://oceans11.lanl.gov/trac/CISM).

Sidebar: Magnetic Storms

Severe space weather (magnetic storms) on the sun can send high-energy particles toward Earth and disrupt GPS satellites and electrical power on the Earth's surface. In one such event in 1859, auroras were visible around the world, and telegraph systems caught fire.

Sidebar: Polynyas

Areas of open water in the ice, called polynyas, occur in the same places deep in the pack ice each year. We know little about these polynyas, as only the strongest icebreakers can reach them. Data suggests that they are very important in energy transfers between the sea and the atmosphere.

Sidebar: Sea Changes

Recent studies have revealed that during the ice ages the sea level varied by more than 130m, and that carbon-dioxide rise preceded the end of the Ice Age.

Sidebar: Antarctic Weather

  • Antarctic Mesoscale Prediction System (AMPS; www2.mmm.ucar.edu/rt/amps)
  • Antarctic Meteorological Research Center (http://amrc.ssec.wisc.edu)
  • NOAA's National Centers for Environmental Information (www.ncdc.noaa.gov)

Sidebar: Antarctic Journals & Websites

  • Antarctic Science, Cambridge University Press
  • Polar Biology, Springer
  • Arctic, Antarctic & Alpine Research, University of Colorado
  • Australian Antarctic Data Centre (http://data.aad.gov.au) Clearinghouse of Antarctic observations.
  • High-resolution image of Antarctica (http://lima.usgs.gov)

Sidebar: Science Reads

  • Dispatches from Continent Seven: An Anthology of Antarctic Science (2016) Rebecca Priestley
  • The Biology of Polar Regions (2008) DN Thomas et al
  • Biology of the Southern Ocean (2nd edition; 2006) G Knox
  • The Ferocious Summer (2007) M Hooper
  • Sea Ice: An Introduction to its Physics, Chemistry and Biology (2003) eds DN Thomas & GS Dieckmann
  • Astronomy on Ice: Observing the Universe from the South Pole (2004) Martin A Pomerantz
  • Encyclopedia of the Antarctic (2007) ed B Riffenburgh

Feature: Pink Snow

Though popular imagination represents snow as white, it can often have a pink, red, orange, green, yellow or gray cast. The phenomena is caused by snow algae, single-celled organisms that live atop snowfields around the world, including many places in the Antarctic Peninsula.

Snow algae have been remarked upon for at least 2000 years, since Aristotle wrote about snow that was ‘reddish in color’ in his History of Animals. In alpine areas of North America, snow algae’s color and fruity scent create what hikers call ‘watermelon snow.’ In Scandinavia, it’s known as ‘blood snow.’ Although people avoid eating it for fear of diarrhea, one study of seven volunteer subjects found no incidence of illness.

Somehow 350 species of snow algae manage to survive in this harsh, acidic, freezing, nutrient-starved, ultraviolet-seared environment. Snow algae tends to live in either high altitudes or high latitudes and reproduces by remarkably hardy spores, which can withstand very cold winters and very dry summers. Researchers are investigating snow algae’s pharmacological potential.

Near penguin rookeries, of course, there’s another reason for the snow’s pinkish-orangish tinge: guano!

Feature: Base Life

Those lucky few who get to spend an extended length of time on the Ice are usually scientists and their support staff. Depending on where you are based, you can have a wide range of experiences. Stations have varying facilities: from primitive huts to well-insulated modern bases with high-tech labs and cushy amenities such as saunas and bars. Food at regularly restocked stations can even include fresh produce.

Small bases are often staffed only by scientists, while large ones, like McMurdo, have a bustling crew of support staff, from hairdressers to heavy-equipment operators. Staff usually stay for up to a year, while some scientists may come for just the few weeks of their observations. No matter the scenario, though, you’ll usually discover a lively sense of camaraderie, and depending on the size of the station, an active social life. McMurdo in summer operates several bars (base members volunteer to bartend) and holds well-attended dances, crafts classes, and sporting events. But winter is a completely different story.

Wintering in Antarctica

Wintering on an Antarctic base can be a life-changing experience. Cut off from the rest of the world for up to eight months (especially on bases outside of the Peninsula) with no flights, boats, or people coming or going can produce interesting effects. Combine that with the lack of sunlight and the amazing physical conditions, and things are extraordinary indeed.

After a station closes the sun begins its continuous sunset circle around the horizon – a glorious sight: wherever you turn, soft colors fill the sky and reflect off the ice. And there is a giddy sense of potential and excitement. The ‘noise’ of the ‘outside world’ can no longer touch you, and the people around you will be your companions for the long haul. The first day you walk outside at lunch and see a night sky, filled with more stars than you’ve ever seen in your life (like a field of white dotted with black, as opposed to the other way round) is absolutely thrilling.

At first, people tuck in and develop friendships and hobbies, acquire new skills, and explore nearby terrain. But as the season advances, the entire group usually begins to experience the effects of long-term sensory deprivation. (At some bases even an emergency medical evacuation is impossible…) There is hardly any precipitation, no plant life, the same people day in and day out (often taking communal meals) and nary a fresh vegetable in sight. Oddly, despite the complete isolation, finding privacy becomes a real concern…you are surrounded by people almost all the time. And the same ones. Escaping your fellow station members can be all but impossible in a place where safety requirements mean that you often cannot stray far from home without at least one companion and a radio.

This profound experience allows life to impact you deeply. The sight of astronomical phenomena, like the aurora australis, are magnificent, and any chance at a ‘boondoggle’ – a trip off-station for fun – is greedily snatched up. With the slow pace of work-life over these long months, there is time for hanging out, and friendships form in the unlikeliest places. People’s behavior can alternate between fraternal and hermit-like.

While some stations maintain traditions each year (like a viewing of The Thing or The Shining, or creating a ‘Midwinter Book’ as did Robert Scott and Ernest Shackleton with poems, paintings and photographs by station members), many people find their attention spans shrink. All those good intentions of reading Shakespeare’s complete works or learning a foreign language ablate like the Antarctic moisture.

In recent years, the advent of email and other internet-based communications have, of course, done a lot to ameliorate the isolation. And old-timers come prepared, knowing what to bring to help them through the lean times of midwinter. But still, the first sight of a warming glow on the horizon can make a grown man dance. There is something primal about seeing the sun after months without, and the heaviest hearts lift immediately. From that point on, even as folks can’t wait to get off the Ice or see a new face when the station opens, there is a wistfulness, a value placed on the last few weeks or months alone, together. The sun rises continuously on the horizon…sometimes creating incredible tableaux: a full moon behind you, a golden sun in front, and the ice colored all shades from indigo to butter-yellow. It’s also at this time, with its cold, cold air that light plays super tricks, refracting through clouds and creating glowing prisms of emanating color.

Then, quickly on the sun’s heels comes the rambunctious return of outsiders for the start of summer, followed by winterovers’ exit to a fecund land (like New Zealand in springtime). Many of the friendships formed on the Ice endure for life and the experiences remain searingly vibrant.

Antarctica During the ‘Age of Reptiles’ – Dr William R Hammer

The first Antarctic terrestrial vertebrate fossil was discovered in 1967. Since the finding of that single jaw fragment in Early Triassic age sediments (245 million years old) near the Beardmore Glacier, four different Mesozoic finds have been collected.

The Early Triassic assemblage is dominated by synapsids, an extinct group of animals that link primitive reptiles to mammals. Perhaps the best-known member is Lystrosaurus, a small herbivore also found on most of the other southern continents and in China and Russia.

In 1985 a vertebrate community of Middle Triassic age (235 to 240 million years old) was found near the first Early Triassic Lystrosaurus site in the central Transantarctic Mountains. This find is dominated by larger synapsids than those from the Early Triassic and includes the wolf-sized carnivore Cynognathus and a large kannemeyerid synapsid related to Lystrosaurus. Two large capitosaurids, Paratosuchus and Kryostega collinsoni, with skulls nearly a meter long, also lived during the Middle Triassic. Kryostega collinsoni is a new genus and species found only in Antarctica.

The first discoveries of Antarctic dinosaurs were made during the late 1980s in Late Cretaceous (65- to 70-million-years-old) deposits on James Ross and Vega islands. These remains included partial skeletons of a nodosaurid ankylosaur (armored dinosaur) and a hypsilophodontid (a small herbivorous ornithopod dinosaur). A few small limb pieces have also been referred to the Theropoda (carnivorous dinosaurs).

In 1998 a single tooth from a hadrosaur (duck-billed dinosaur) was discovered on James Ross Island, and in 2003 a fragmentary specimen of a small (1.8m-long) dromeosaurid theropod was found on Vega Island.

In addition to the terrestrial animals, large extinct marine plesiosaurs have been found on islands near the Antarctic Peninsula. These long-necked animals with paddle-shaped fins (made famous as the Loch Ness Monster) are not dinosaurs but lived concurrently. One of the more spectacular plesiosaur specimens was discovered on Vega Island in 2005. It is a nearly complete, well-preserved juvenile plesiosaur that was apparently killed by a volcanic eruption.

Uniquely Antarctic Dinosaurs

A fourth terrestrial vertebrate community was found in 1990, again near the Beardmore Glacier. This Early Jurassic (190- to 20- million-years-old) find includes the nearly 7m-long bipedal carnivorous dinosaur Cryolophosaurus (‘frozen-crested reptile’). Represented by the most complete dinosaur skeleton found in Antarctica, Cryolophosaurus is the first dinosaur known to be unique to the continent (the Cretaceous dinosaurs are too incomplete to determine whether or not they represent new genera). The Latin ‘cryo’ was included in the name because, although Antarctica wasn’t frozen when the dinosaur lived, we nearly froze to death while collecting it.

Ribs of a prosauropod were in the mouth of the cryolophosaur when it died, leading to the assumption that the carnivore may have choked to death on its last meal. Prosauropods were smaller (7.5m-long) predecessors to the well-known large sauropods (Apatosaurus, Brachiosaurus) of the later Jurassic. A new taxon was named (Glacialisaurus hammeri), the second dinosaur known to be unique to Antarctica.

After the Cryolophosaurus died along an Antarctic riverbank 200 million years ago, smaller carnivorous theropods scavenged the skeleton. Gnaw marks were found on some of the bones, and small broken theropod teeth were collected nearby. Other members of Jurassic fauna are represented by single elements, including a tooth from a rodent-like synapsid and the upper arm of a small pterosaur (flying reptile).

These finds suggest that Antarctic climates were relatively mild during the Mesozoic, and that connections existed between Antarctica and the other southern continents.

Dr William R Hammer is Chair of the Geology Department at Augustana College. Glacialisaurus hammeri was named for him, and he discovered Cryolophosaurus with William Hickerson.

Antarctica’s Hot Spots – Dr Philip Kyle

Beneath the icy exterior of Antarctica is a dynamic continental geologic plate. Tectonic forces are at work within the Antarctic plate, and in places the continent is slowly being torn apart by rifting, much like East Africa. As the Earth’s crust is extended and thinned, deep hot mantle rises and partially melts to form basaltic magma, which rises and is often stored within the crust in magma chambers. Where the magma reaches the surface, it is erupted as lava or volcanic ash and volcanoes are formed.

Active volcanoes are found today in three areas of Antarctica: the western Ross Sea, West Antarctica and along the Antarctic Peninsula. There remains a high probability that significant volcanic eruptions could occur at any time in Antarctica.

In the western Ross Sea region, most volcanism occurs on or along the front of the Transantarctic Mountains. Many small volcanic vents have been detected beneath the Ross Sea as magnetic anomalies, but none of these vents are currently active. Among a group of volcanic cones and domes called the Pleiades, high in the Transantarctic Mountains of northern Victoria Land, is a very young-looking dome, which probably erupted less than 1000 years ago. Mt Melbourne, near Terra Nova Bay, has steaming ground at its summit and an ash layer showing it erupted less than 250 years ago.

In Marie Byrd Land of West Antarctica, only Mt Berlin is considered active. There is also a possibility that an eruption is currently ongoing beneath the ice of the West Antarctic ice sheet. Airborne studies have shown a circular depression consistent with the melting of the ice by a volcanic vent. The presence of a volcano beneath the depression is confirmed by studies that show magnetic rocks typical of volcanoes.

In the Antarctic Peninsula region, volcanic Deception Island lies at the southern end of Bransfield Strait.

Mt Erebus

Antarctica’s best-known volcano is Mt Erebus, a stratovolcano on Ross Island, discovered by James Clark Ross in 1841. Ross noted in his journal that Erebus was erupting, 'emitting flame and smoke in great profusion…some of the officers believed they could see streams of lava pouring down its sides until lost beneath the snow.’ Erebus is one of the largest volcanoes in the world, ranking among the top 20 in size.

Erebus has many unusual features, the most notable being a permanent convecting lake of molten magma with a temperature of 1000°C (the only others are Erta Ale in Ethiopia and Nyiragongo in Congo). In late 2007 the lake was 35m in diameter. The magma, which is very rich in sodium and potassium, is called phonolite. This name comes from German and refers to rocks that ring like a bell when hit.

Erebus Crystals

Unique to Erebus is the occurrence of large crystals in the magma. They can exceed 10cm in length and take many different forms. Easily eroded out from the soft, glassy matrix of volcanic bombs erupted from the volcano, the crystals litter the upper crater rim like a carpet. They are of a mineral type called feldspar and belong to the anorthoclase variety. The anorthoclase is spectacular, and among the most perfect and largest crystals found in volcanic rocks anywhere on Earth.

Ice Towers

Erebus’ summit features beautiful fumarolic ice towers. From sea level these can be observed with binoculars on the upper summit plateau of the volcano. The ice towers represent places where heated gases, rich in water, vent to the surface along fractures. When the gas reaches the cold air, the water freezes and forms bizarre shapes of varying size. Beneath the ice towers it is common to find tunnels and caves melted into the underlying snow and ice. These ice caves are warm and steamy and in some cases feel like a sauna. Access to the cave system can be difficult and may require an abseil (rappel) of more than 20m. During the summer, when the sun dips toward the horizon around midnight, the ice towers look spectacular, as steam slowly ascends through the hollow towers and vents out the top.

Eruptions

Small eruptions are common from Erebus’ magma lake, occurring six to 10 times daily during the mid-1980s and 1990s. Eruptive activity declined between 2000 and 2004 but was at a high level in 2005 and 2006 before going ‘quiet’ again in mid-2007. Activity was observed once again in 2010. The eruptions are referred to as Strombolian eruptions, after the volcano Stromboli near Sicily. Only rarely are volcanic bombs ejected from the lake onto the 600m-diameter crater rim. In March 2007 several bombs destroyed scientific equipment on the rim.

In September 1984 there was a four-month episode of more violent eruptions that showered bombs more than 3km from the vent inside the crater. Scientists had to abandon a small research facility near the crater rim while volcanic bombs – some as big as cars – rained down around the summit crater. The bombs whistled as they fell, but the most memorable part of the eruption was the sound of the sharp explosions that threw the bombs from the volcanic vent. (Upon landing, the bombs crackle as they cool. The interior of the bombs can be very hot, and if you break one open, you can pull the plastic hot lava out like taffy candy.)

Seismic Measurements

Today a network of about a dozen seismic stations (which have continuous GPS, microphones and meteorological sensors) monitors Erebus, recording its small explosions and the earthquakes within its bowels. Between 2000 and 2004 the seismometers recorded tremor events generated by collisions between huge icebergs that broke from the Ross Ice Shelf. The seismometers should allow scientists to predict the next episode of eruptions. While there’s no evidence in the geologic record of huge eruptions of the magnitude of the 1980 eruption at Mt St Helens in the US, the presence of volcanic ash from Erebus in blue ice near the Transantarctic Mountains, several hundred kilometers from the volcano, attests to its potential for larger eruptions.

Dr Philip Kyle, Professor of Geochemistry at the New Mexico Institute of Mining and Technology and Director of the Mount Erebus Volcano Observatory (erebus.nmt.edu), has spent 40 field seasons in Antarctica and returns annually to Mt Erebus to monitor its activity.