The Antarctic region is of immense strategic importance to Australia, not only because Australia claims 42% of Antarctica, but also because the Antarctic Treaty provides that all of the planet below 60 degrees South is a demilitarised zone. Antarctica plays a large role in the global climate system. The vast, cold continent holds about 90% of the world’s ice—or around 60% of the world’s fresh water.
The Southern Ocean surrounding Antarctica is a significant driver of the planet’s ocean currents, and links the Indian, Pacific and Atlantic oceans. The Southern Ocean stores heat and carbon, which has served to limit the rate of climate change to date. The world’s oceans have stored about 30% of the additional carbon dioxide produced by humans since pre-industrila times , and 90% of the extra heat generated by human activities since the 1960s . The ocean below 40 degrees South is responsible for about 40% of the global ocean take-up of anthropogenic carbon dioxide.
The 5th Assessment Report from the Intergovernmental Panel on Climate Change (IPCC) concluded that the observed warming of the Earth is strongest in the polar regions, and that surface temperatures over large areas of the Antarctic Peninsula have risen considerably faster than the global average. The Southern Ocean is also warming more rapidly than the global ocean average. The Antarctic Peninsula is showing the most obvious signs of change in the form of increased loss of ice shelves and subsequent greater glacial flow.
There have been significant seasonal changes in sea ice distribution in the peninsula region, including an overall loss of around 25% of sea ice, and a shortening of the annual period when the surrounding ocean is covered by sea ice. Those regional changes in the sea ice season and distribution have, among other things, changed the behaviour of the krill fishing industry by allowing longer and greater access to krill stocks.
In other parts of the Antarctic, especially in the Ross Sea region south of New Zealand, the maximum annual sea ice cover has increased. And overall, the annual sea ice extent around Antarctica has shown a small increasing trend of between 1 and 2% per decade for the period 1979 to 2012.
The West Antarctic ice sheet has been losing mass—that is, more ice is lost to the sea than accumulates in the ice sheet. This decrease has been partly offset by increased snowfall in East Antarctica. It’s been estimated that Antarctica as a whole contributed around 0.14mm per year to global sea-level rise from 1961 to 2003, a rate that rose to 0.21mm in the period from 1993 to 2003. Global mean sea level has risen by 0.19m from 1901−2010. The IPCC says it’s likely that the rate of sea level rise increased to 3.2mm per year 1993 and 2010.
The contribution of the Greenland and Antarctic ice sheets is the greatest current uncertainty in global projections of sea-level rise—increased loss of ice from Antarctica will push up global sea-level rise projections.
Increased carbon dioxide in the atmosphere has led to changes in the acidity of the Southern Ocean and has the potential to impact the ocean’s marine life and ecosystems. And changes in ocean temperature have led to changes in species distribution and abundance in Antarctica, and the rapid expansion of ranges for some species like the king crab, with consequential changes to ecosystems.
Climate models indicate that the Southern Ocean will continue to change in response to increased greenhouse gas emissions, producing further ocean warming and freshening, changes in ocean currents, a greater contribution to sea-level rise through glacial melt, and regional changes in the extent and volume of Antarctic sea ice. Although surface temperatures in Antarctica and the Southern Ocean will warm more slowly than elsewhere on the planet, the projected changes are profound. The warming of deep ocean waters surrounding Antarctica is happening far more rapidly than in any other ocean.
The Southern Ocean supports the world’s largest underexploited fishery—the Antarctic krill fishery. Reductions in sea ice will reduce ‘natural’ barriers to shipping access in high latitudes and open up otherwise difficult areas for marine resources harvesting. Those activities are managed under the Antarctic Treaty System, and Australia has an interest in ensuring that international decisions take account of account of the best available science.
The expansion of membership of the Antarctic Treaty and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), has seen some of the norms of the Antarctic Treaty System challenged. That’s particularly the case in CCAMLR where some countries have begun to put forward views on fisheries that fundamentally challenge the conservation principle of the convention.
While illegal, unregulated and unreported (IUU) fishing has declined dramatically in the Antarctic, there’s always the potential for new players to enter the scene, and Australia and other Antarctic countries must continue their efforts to eradicate the scourge of IUU fishing.
In recent times there has been increased speculation about the potential for mineral resource activity in Antarctica, even though it’s banned indefinitely by the Madrid Protocol. Potentially greater access to the sea-bed in some parts of the Antarctic may provoke countries to challenge the norms of the Antarctic Treaty System, or at least use the lure of resource exploitation for domestic political advantage.
Successive Australian Governments have championed the Madrid Protocol’s ban on mining in Antarctica and the goal of CCAMLR to conserve Antarctica’s marine living resources and protect the Antarctic ecosystem. As interest in Antarctica’s resources grows, Australia and like-minded countries need to concentrate their scientific and diplomatic resources to protect the Antarctic environment.
The strongest protection for Australia’s Antarctic interests is active engagement in, and the ability to lead, international efforts in Antarctic collaboration, science and diplomacy. The Antarctic region is of immense strategic importance to Australia and must be front of mind for the Australian government as it considers how it can sustain a strong position as our interests in the region face new challenges from the changing climate.