The ‘Know Your Region’ series is designed to support unit and individual professional military education on the South East Asian region and beyond. It’s important for all serving members of our military to have a foundational knowledge of the countries and lands surrounding Australia.


On this page:

  • Climate Change and the Ozone Hole
  • Australia's 'Frozen' Claim


Climate Change and the Ozone Hole

The Antarctic region has an important role in global climate processes. It is an integral part of the Earth’s heat balance. The heat balance, also called the energy balance, is the relationship between the amount of solar heat absorbed by Earth’s atmosphere and the amount of heat reflected back into space.

Ice is more reflective than land or water surfaces. The massive Antarctic Ice Sheet reflects a large amount of solar radiation away from Earth’s surface. As global ice cover (ice sheets and glaciers) decreases, the reflectivity of Earth’s surface also decreases. This allows more incoming solar radiation to be absorbed by the Earth’s surface, causing an unequal heat balance linked to global warming, the current period of climate change.

Interestingly, NASA scientists have found that climate change has actually caused more ice to form in some parts of Antarctica. They say this is happening because of new climate patterns caused by climate change. These patterns create a strong wind pattern called the ‘polar vortex.’ These winds lower temperatures in the Antarctic and have been building in strength in recent decades – as much as 15% since 1980. This effect is not seen throughout all of the Antarctic, however, and some parts are experiencing ice melt.

More broadly, climate change in Antarctica is resulting in rising temperatures and increasing snowmelt and ice loss. A summary study in 2018 incorporating calculations and data from many other studies estimated that total ice loss in Antarctica due to climate change was 43 gigatons per year on average during the period from 1992 to 2002 but has accelerated to an average of 220 gigatons per year during the five years from 2012 to 2017. In parallel, a study has shown for the first time that the continent-wide average surface temperature trend of Antarctica was slightly positive from 1957 to 2006. This means some of Antarctica has been warming up; particularly strong warming has been noted on the Antarctic Peninsula. Over the second half of the 20th century, the Antarctic Peninsula was the fastest-warming place on Earth, closely followed by West Antarctica, but these trends weakened in the early 21st century. Conversely, the South Pole in East Antarctica barely warmed last century, but in the last three decades (1989 to 2018) the temperature increases of 0.61 ± 0.34° Celsius per decade has been more than three times greater than the global average. However, this warming lies within the upper bounds of the simulated range of natural variability, leading researchers to conclude that extreme decadal variability has masked warming due to human activity across interior Antarctica during the 21st century.

In February 2020, the continent recorded its highest temperature of 18.3°C, which was a degree higher than the previous record of 17.5°C in March 2015. This high was again recorded on 1 July 2021 at the Argentinian Esperanza Base and confirmed by the United Nations’ World Meteorological Organisation.

In 2002, the Antarctic Peninsula's Larsen-B ice shelf collapsed. Between 28 February and 8 March 2008, about 570 square kilometres of ice from the Wilkins Ice Shelf on the southwest part of the peninsula collapsed, putting the remaining 15,000 km2 of the ice shelf at risk. The ice was being held back by a ‘thread’ of ice about six kms wide, prior to its collapse on 5 April 2009. With 80% of the world freshwater reserves stored in Antarctica, it is estimated to be enough to raise global sea levels by about 60 metres if all of it were to melt.

The waters surrounding Antarctica are a key part of the ‘ocean conveyor belt,’ a global system in which water circulates around the globe based on density and on currents. The cold waters surrounding Antarctica, known as the Antarctic Bottom Water, are so dense that they push against the ocean floor. The Antarctic Bottom Water causes warmer waters to rise or upwell. Antarctic upwelling is so strong that it helps move water around the entire planet. This movement is aided by strong winds that circumnavigate Antarctica. Without the aid of the oceans around Antarctica, the Earth’s waters would not circulate in a balanced and efficient manner.

A main component of climate variability in Antarctica is the Southern Annular Mode, which showed strengthened winds around Antarctica in summer of the later decades of the 20th century, associated with cooler temperatures over the continent. The trend was at a scale unprecedented over the last 600 years; the most dominant driver of this mode of variability is likely the depletion of ozone above the continent. To learn about the Thwaites Glacier, sometimes referred to as the Doomsday Glacier, watch the following in-depth ABC report.

Through a combination of ground-based and satellite measurements, scientists in the early 1980s began to realise that Earth’s natural sunscreen was thinning dramatically over the South Pole each spring. This thinning of the ozone layer over Antarctica was announced in May 1985 and came to be known as the ozone hole. Attributed to the emission of chlorofluorocarbons or CFCs into the atmosphere, which decompose the ozone into other gases. Scientists found out these long-lived chemicals that had been used in refrigerators and aerosol sprays since the 1930s had a dark side. In the layer of the atmosphere closest to Earth (the troposphere), CFCs circulated for decades without degrading or reacting with other chemicals. When they reached the stratosphere, however, their behaviour changed. In the upper stratosphere (beyond the protection of the ozone layer), ultraviolet light caused CFCs to break apart, releasing chlorine, a very reactive atom that repeatedly catalyses ozone destruction. The detection of the hole and its cause, reoccurring every spring since the 1970s, spurred the signing of the Montreal Protocol in 1987, an international agreement phasing out the use of ozone-depleting chemicals. Thus, the ozone hole opened the world’s eyes to the global effects of human activity on the atmosphere.

The global recognition of the destructive potential of CFCs propelled the Protocol guiding the phasing out the production of ozone-depleting chemicals. Scientists estimate that about 80% of the chlorine (and bromine, which has a similar ozone-depleting effect) in the stratosphere over Antarctica today comes from human, not natural, sources. The word hole is not literal; no place is empty of ozone. Scientists use the word hole as a metaphor for the area in which ozone concentrations drop below the historical threshold of 220 Dobson Units. Using this metaphor, they can describe the hole’s size and depth. The recorded maps show the state of the ozone hole each year on the day of maximum depth – the day the lowest ozone concentrations were measured. Watch the National Geographic’s breakdown of the ozone depletion below.

The ozone layer prevents most harmful wavelengths of ultra-violet (UV) light from passing through the earth's atmosphere. The loss of ozone has also led to increased winds and storms, both in frequency and strength. Winds in the Southern Ocean have been estimated to have increased by 15-20%. It has caused a low-pressure system to form in the Amundsen Sea again both with increased frequency and strength. This low pressure sucks cold air from the interior of Antarctic and across the Ross Sea leading to a great increase in the amount of sea-ice forming in this area in recent years. Ozone depletion has been shown to harm a variety of Antarctic marine plants and animals (plankton). The hole in the Earth's ozone layer over the South Pole has affected atmospheric circulation in the Southern Hemisphere all the way to the equator. Antarctica also has a profound influence on Australian and New Zealand weather and climate.

Climate change is affecting the Southern Ocean in many ways. The surface water is warming, and there are changes occurring deep below the surface as well. The warmer surface water is increasing the melt of the floating glacial ice, causing more freshwater to enter the oceans, and increasing the rate of sea level rise. Changes in the structure of the Southern Ocean through climate change will have impacts globally, on weather, climate, and fisheries.

Since the 1990s, satellites have shown accelerating ice loss driven by ocean change. Although considerable uncertainty remains, scientists are increasing our understanding and ability to model potential impacts of ice loss. Ozone depletion may have a dominant role in governing climatic change in Antarctica (and a wider area of the Southern Hemisphere). Ozone absorbs large amounts of ultraviolet radiation in the stratosphere. Ozone depletion over Antarctica can cause a cooling of around 6° C in the local stratosphere. This cooling has the effect of intensifying the westerly winds which flow around the continent (the polar vortex) and thus prevents outflow of the cold air near the South Pole. As a result, the continental mass of the East Antarctic ice sheet is held at lower temperatures, and the peripheral areas of Antarctica, especially the Antarctic Peninsula, are subject to higher temperatures, which promote accelerated melting. Models suggest that ozone depletion and the enhanced polar vortex effect also account for the period of increased sea ice just offshore of the continent. Thus, the depletion of the ozone hole has also caused an overall cooling trend on the Antarctic continent, which has masked to some extent the effects of warming temperatures, particularly on the larger part of East Antarctica and areas away from the peninsula region.

Models suggest that the concentration of chlorine and other ozone-depleting substances in the stratosphere will not return to pre-1980 levels until the middle decades of the 21st century. This hole covers almost the whole continent and was at its largest in September 2006. Scientists have already seen the first definitive proof of ozone recovery, observing a 20% decrease in ozone depletion during the winter months from 2005 to 2016. In 2016, a gradual trend toward ‘healing’ of the ozone hole was reported and then again in 2017. It is reported that the recovery signal is evident even in the ozone loss saturation altitudes. In 2019, the ozone hole was at its smallest since 1982, due to the warmer polar stratosphere weakening the polar vortex. This reduced the formation of the 'polar stratospheric clouds' that enable the chemistry that leads to rapid ozone loss.

Yet, the Antarctic ozone hole is expected to continue for decades. Some models predict that it will mostly recover by 2040, others put the timeline of ozone concentrations in the lower stratosphere returning to pre-1980 levels by about 2060 to 2075. These variations in estimates are due to the potential for an increase in atmospheric concentrations of ozone-depleting substances, including a larger predicted future usage in developing countries. Another factor that may prolong ozone depletion is the drawdown of nitrogen oxides from above the stratosphere due to changing wind patterns. For an update on the ozone layer, check out the following Vox report.

Even if global temperature rise is limited to the Paris Agreement's stated temperature goals of capping global mean temperature increases to 1.5 to 2° C above pre-industrial levels, there is still concern that West Antarctic ice-sheet instability may be already irreversible. If a similar trajectory, still under the global temperature limit goals, persists, the East Antarctic Ice Sheet may also be at risk of permanent destabilisation. It has been shown using physics-based computer modelling that even with a 2° C reduction in global mean temperatures Antarctic ice loss could continue at the same rate as it did in the first two decades of the 21st century.

The continued effects of climate change are likely to be felt by animal populations as well. Adélie penguins, a species of penguin found only along the coast of Antarctica, may see nearly one-third of their current population threatened by 2060 with unmitigated climate change. Emperor penguin populations may be at a similar risk, with 80% of populations being at risk of extinction by 2100 with no mitigation. With Paris Agreement temperature goals in place, however, that number may decline to 19% under the 2°C goal or 31% under the 1.5°C goal. Warming ocean temperatures have also reduced the number of krill and other small crustaceans in the ocean surrounding Antarctica, which has led to the inability of baleen whales to recover from pre-whaling levels. Without a reversal in temperature increases, baleen whales are likely to be forced to adapt their migratory patterns or face local extinction.

Finally, the development of Antarctica for the purposes of industry, tourism, or an increase in research facilities, may put direct pressure on the continent and threaten its status as largely untouched land. For another explanation of the Thwaites Glacier, check out the following video.

Explore the following resources to see the deep connections between Antarctica and climate change.


Australia's 'Frozen’ Claim

Antarctica is changing. Not just physically as climate change inexorably impacts but also in how countries and people perceive and act in the world’s last uninhabited continent. More and more states are becoming engaged in Antarctic issues and establishing research bases there. The scientific endeavours of all the participating Antarctic states use a judicious mix of military and commercial air transport assets. Australia is notable in this use of national air power in Antarctica, albeit on a small-scale. Sizeable investments have and are being made to create an effective and efficient air logistic network. Australia has a long association with this part of the continent.

By virtue of the Antarctic Treaty, signed in 1959, the territorial claims to Antarctica of seven of the original signatories were held in abeyance or ‘frozen.’ Considered by many as an exemplar of international law, the Antarctic Treaty System (ATS) of governance is being challenged by contemporary global scenarios. In this context, it is necessary to gain a clearer understanding of the weight of those initial claims, which stand (despite being frozen) as a cornerstone of the treaty.

The first claim to the Antarctic continent was made in 1908, when the United Kingdom issued the original Letters Patent; it included a sizeable slice of Argentian and Chilean Patagonia and so, had to be reissued in 1917. The British claim was followed by those of New Zealand (1923), France (1924), Australia (1933), Norway (1939), Argentina (1940), and Chile (1940). The British, Argentinian, and Chilean claims overlapped over the Antarctic Peninsula and some sub-Antarctic islands, while – with the exception of Norway at the time – all the claims extended all the way to the South Pole. Less than 20% of the territory, known as Marie Byrd Land, remained unclaimed.

The first exploration and discovery of the sub-Antarctic islands and of the Antarctic landmass and surrounding sea is a reason given by the British, Norwegians, French, Australians, and New Zealanders to support their territorial claims. The Australian Antarctic Division began its long association with the frozen continent with the 1911–1914 Australasian Antarctic Expedition led by Douglas Mawson. They had bases at Commonwealth Bay (south of Tasmania) and the Shackleton Ice Shelf (south of Perth). The expedition explored extensively along the coast near the bases. Watch the following video by Behind the News for an overview of Mawson’s expedition.

As part of the Commonwealth, Australia and New Zealand rely on the transfer of title from the British Empire to ground their claims. In the case of New Zealand, this goes back to 1923, when the Ross Dependency was established and given to the Governor-General of New Zealand. Ten years later, the one-paragraph-long Australian Antarctic Territory Acceptance Act came into effect. Through it, Britain transferred its sovereignty over vast areas of Antarctica with more territorial additions following in 1947.

In 1954, Australia’s first continental research facility, Mawson Station, was established; it is now the longest continuously operating station south of the Antarctic Circle of any nation. Since then, Australia has built another two permanent scientific research stations in the Australian Antarctic Territory that all contribute to an internationally significant ongoing scientific research program. The Department of Agriculture, Water and the Environment, through its Australian Antarctic Division (AAD) in Hobart leads, coordinates and delivers the Australian Antarctic programme and administers the Australian Antarctic Territory, Heard Island, and McDonald Islands.

Since the designation of the Australian Antarctic Territory pre-dated the signing of the Antarctic Treaty, Australian laws that relate to Antarctica date from more than two decades before the Antarctic Treaty era. In terms of criminal law, the laws that apply to the Jervis Bay Territory (which follows the laws of the Australian Capital Territory) apply to the Australian Antarctic Territory. Key Australian legislation applying to the Antarctic Treaty System (ATS) decisions include the Antarctic Treaty Act 1960, the Antarctic Treaty (Environment Protection) Act 1980 and the Antarctic Marine Living Resources Conservation Act 1981.

The importance of continual scientific research on the southern continent in justifying claims of sovereignty continues today. Indeed, free access to Antarctica and the Southern Ocean for scientific research is perhaps one of the least appreciated resources in Antarctic governance. The Treaty privileges science as one of the main activities in Antarctica. In order to maintain credibility as leading Antarctic states it is essential that Australia and New Zealand engage in high quality science there, and good science requires good logistic support.

Each nation with a research station in Antarctica treats their bases as though they were registered vessels and applies national laws there, including the right to exclude others. This situation amounts to regional custom, independent of the Antarctic Treaty. Seen in the video below where the AAD hold a citizenship ceremony.

Previous methods of legitimising land claims varied from Argentina sending women to give birth on its Antarctic research stations, to the British establishing a post office complete with the relevant forms for television licenses and car tax applications. Modern claims are made not with flags and inscribed brass cylinders, such as the one U.S. pilot Lincoln Ellsworth dropped there in 1935, but with maps of the seabed and papers lodged with the United Nations. The more scientific bases and work sites a nation has in Antarctica, the more de facto control their government has over territory there. China is developing its fifth base in Antarctica and plans more; Russia has six active bases.

Interestingly, around 15% of Antarctica remains unclaimed. Just east of the Ross Ice Shelf lies Marie Byrd Land, a vast, remote territory that is by far the largest unclaimed land area on Earth. For more information about the unclaimed land remaining on the southern continent watch the following video.

Australia’s claim and those of six other nations have been deliberately set aside. This has created the unusual situation that in a contemporary international system (nearly) completely divided into distinct sovereign states, Antarctica is not deemed anyone’s territory. Antarctica is instead ‘ruled’ multilaterally through international committees based on mutually decided treaties and agreements. However, an increasing number of states now want to influence these treaties and agreements.

The Australian Government in 2016 released the Australian Antarctic Strategy and 20 Action Year Plan. This document sets the vision and the policy intentions for Australia’s future engagement with Antarctica. Australia’s declared national interests in Antarctica are:

  1. maintain Antarctica's freedom from strategic and/or political confrontation;
  2. preserve our sovereignty over the Australian Antarctic Territory, including our sovereign rights over adjacent offshore areas;
  3. support a strong and effective Antarctic Treaty System;
  4. conduct world-class scientific research consistent with national priorities;
  5. protect the Antarctic environment, having regard to its special qualities and effects on our region;
  6. be informed about and able to influence developments in a region geographically proximate to Australia; and
  7. foster economic opportunities arising from Antarctica and the Southern Ocean, consistent with our Antarctic Treaty system obligations, including the ban on mining and oil drilling.

There may appear some seeming incompatibilities between these various interests especially that between preserving Australian sovereignty and supporting the ATS. The ATS sets aside Australia’s claim, so it does not preserve Australia’s sovereignty but instead disregards it. The counter argument is that while the ATS continues, no nation can make a counterclaim to Australia’s. Under this perspective, the ATS keeps Australia’s claim safe and crucially achieves another key Australian objective: keeping Antarctica free from strategic conflict.

Australia has three medium-sized, all-season bases spread out along the East Antarctic coast and principally supported logistically and administratively from Hobart. They are a significant presence. Yet, there is an obvious and sharp distinction between the coastal stations and the inland, high-altitude facilities built on the ice-covered Antarctic plateau with its average elevation of some 3,000 metres. Australia is re-acquiring an Antarctic overland traverse capability but has no inland bases such as those China, Russia, France, and Italy do (albeit some are summer-only facilities).

The Australian bases are logistically supported using air and sea transport. Shipping provides the logistic backbone of the Australian Antarctic programme. The recently retired, MV Aurora Australis, was an 8,400 tonnes multi-purpose research and resupply ship built in Newcastle Australia and came into service in 1990. The icebreaker provides essential fuel and supplies to the three Australian stations, undertakes personnel transfer, and is used for marine scientific research. Its Romanian-built replacement, the RSV Nuyina, at 25,500 tonnes displacement is significantly larger than the Aurora Australis and has much greater cargo and fuel carrying capacity. The Nuyina will have space for four AS350 Squirrel helicopters or two medium-sized helicopters similar to Sikorsky S92s. To get an inside look inside the recently decommissioned Aurora Australis icebreaker, check out the video below.

Air operations can be divided into inter- and intra-continental. They have become increasingly important especially for personnel movement. Mawson Station has a summer ski runway constructed either on nearby sea ice if present, or more often inland about 10kms from Mawson at Rumdoodle. Davis station in the ice-free Vestfold Hills uses a ski runway on the Davis Plateau some 40km from the station and is reconstructed each year on snow. Casey’s principal airfield is Wilkins, some 70km inland and sited 700m above sea level. The Wilkins runway has a foundation of natural glacial ice, which after annual surface grooming can accept large wheeled transport aircraft as well as smaller ski-equipped aircraft. Wilkins is open between October and March each year but closes for about six weeks in the middle of summer as warmer temperatures cause sub-surface melting that undermines runway strength and creates blisters. This mid-summer melt issue is likely to get worse as global warming worsens.

For more information see the paper, 'Australia's Antarctic National Air Power Futures', published in 2019 by the Air and Space Power Centre. It examines Antarctica today and the challenges to Australia’s assertions of sovereignty in the East Antarctic region. Going on to identify Canberra’s interests, current air operations, and development intentions. Then it looks forward by two decades to develop four alternative futures both appropriate to Antarctic air operations and linked to the Australian Defence Force’s 2035 Future Operating Environment’s alternative futures. The last section applies these futures to devise a range of strategic options in terms of potential Australian Antarctic national air power approaches and possible force structure changes. Then listen to Dr Joanna Vince’s explanation of the south pole’s governance and the challenge posed by Australia’s sovereign claims – territorial, maritime, and exclusive economic zone – which remain on ice.

See #KYR – Antarctica: Information article for more information on Australia’s Antarctic Division.