Antarctica

The Antarctic Ozone Hole

You may have heard of the hole in the ozone layer above the Antarctic. CFCs (chlorofluorocarbons) cause ozone depletion when they are released into the atmosphere. These gases were widely used in refrigerators and as propellant in aerosol sprays.  The Montreal Protocol of 1987 effectively banned their use by most leading industrial nations, though a few nations have actually increased their use of CFCs since this time.  Developed countries have been reducing their consumption of HCFCs and were due to completely phase them out by 2020. Developing countries agreed to start their phase out process in 2013 and are now following a stepwise reduction until the complete phase-out of HCFCs by 2030. 

The extreme cold of the Antarctic may also be a factor in ozone depletion, as there is a similar hole over the Arctic. 

Melting Ice Sheets

The burning of forests and fossil fuels has resulted in a 25 per cent increase in the carbon dioxide deposits found in Antarctic snow since the 1970s. 'Greenhouse gases' like carbon dioxide, which is produced by burning fossil fuels trap some of the sun's heat and warm the atmosphere, causing global warming.

Over the past 50 years, the west coast of the Antarctic Peninsula has been one of the most rapidly warming parts of the planet.  The Peninsula is particularly sensitive to small rises in the annual average temperature  and it is causing sea ice to melt.

Warmer ocean temperatures are making ice shelves increasingly susceptible to breaks and collapses, and already some have collapsed.  Icebergs are created as great chunks of ice break off the edges of ice shelves.

The Larsen Ice Shelf is a long ice shelf in the northwest part of the Weddell Sea, extending along the east coast of the Antarctic Peninsula.  In January 1995, the Larsen A ice shelf collapsed and in 2002 the majority of the Larsen B ice shelf collapsed dramatically.  Just recently, in July 2017, one of the world's largest icebergs broke off from Antarctica's Larsen C ice shelf.

There has been no significant loss of ice from the 96% of Antarctica that is not the Peninsula.  It is so cold here (average surface temperature of continental Antarctic is about -37ºc, compared to -5ºc for the warmest places on the Peninsula), that even if temperatures were to rise by the same amount as they have on the Peninsula, there still wouldn’t be any melting. 

Recently, however, it has been discovered that the East Antarctic ice sheet is more vulnerable to melting than was first thought. A new paper in the journal Nature suggests that a large part of it collapsed only 400,000 years ago and this change happened during an extended but relatively mild warm spell. The greenhouse gases that humans have produced to date may have already locked in 42 feet of eventual sea level rise from all of the glaciers predicted to melt in the coming centuries, including the ones in East Antarctica.

Historic Secrets in the Ice

Antarctica plays a vital role in the world's climate and atmospheric patterns. Nearly 90 per cent of the world's ice is contained in the Antarctic's ancient ice sheets. By drilling into the ice, scientists can read the world's climatic history from as far back as half a million years ago, through deposits etched in the ice layers. These ice deposits tell us, for example, that 18,000 years ago, the world was probably far windier and dustier because Antarctic ice from that period contains more dust than fresh snow and the dust comes from other continents. 

Threats to Animal Life in the Antarctic

Antarctic animals depend on the sea for their food, with bird and mammal populations concentrated in the ocean and around the marginal coastal areas. The tiny, shrimp-like krill is central to the food chain of all Antarctic life. Each individual krill measures about 4cm long and has a life span of up to seven years. The krill is the staple food source for five whale species, three groups of seal and many species of fish and birds, including penguins.

Fishing nations started to exploit krill around the Antarctic during the 1970s. Improved harvesting techniques, and the discovery of wide uses for krill in animal and human foods led to yearly catches of over 400,000 tonnes. We do not know enough about the krill's life cycle to be sure that it can withstand such fishing, and a large drop in its numbers could spell doom for animals higher up in the food chain, such as whales, but these warnings have gone unheeded.

Overfishing of Antarctic Ocean fish species has also taken place. Three varieties of Antarctic fish are heavily depleted and there is serious concern over the survival of the ice fish species.

The main species that are commercially fished in the Antactic are Antarctic Krill and Patagonian and Antarctic Toothfish and they are still in danger of depletion. However, the U.N.'s Food and Agricultural Organization's agreement on Port State Measures to Prevent, Deter, and Eliminate illegal, Unreported, and Unregulated Fishing will make it more difficult for illegal vessels to operate.

CCAMLR - Protecting Antarctic Wildlife

Brought into effect in the spring of 1982, the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) is the only international agreement which gives protection to wildlife living in the Antarctic. In 2020, CCAMLR is an international commission with 26 Members, and a further 10 countries have acceded to the Convention. CCAMLR forbids the killing or wounding of any native bird or mammal - except whales - without a permit, and states that damage to and interference with habitats should be minimised.

On the 28th October 2016 at its annual meeting in Hobart, Tasmania, a Ross Sea marine park was finally declared by the CCAMLR, under an agreement signed by 24 countries and the European Union. It protects 1.57 million square kilometres of sea, and is the world's largest marine protected area.  Commercial fishing is banned within the marine protected area for 35 years.

The Ross Sea, together with its shelf and slope only comprise 2% of the Southern Ocean.  However,  38% of the world's Adelie penguins live there, along with 30% of the world's Antarctic petrels and around 6% of the world's population of Antarctic minke whales.  The Ross Sea is also home to huge numbers of krill, a staple food for species including whales and seals. Their oil is critical for salmon farming. However there are concerns that overfishing and climate change are having significant impacts on their numbers.

Credits

Image: antarctica by Martha de Jong-Lantink

Information sourced from:

CCAMLR (2015), Krill fisheries and sustainability [online], Available from: https://www.ccamlr.org/en/fisheries/krill-fisheries-and-sustainability [accessed 20/05/2015]

MercoPress (2015), Beware: China announces to seven-fold increase Antarctic krill catches [online], Available from: http://en.mercopress.com/2015/04/30/beware-china-announces-plan-to-seven-fold-increase-antarctic-krill-catches [accessed 20/05/2015]

Antarctic and Southern Ocean Coalition (2014), Southern Ocean Fisheries [online], Available from:  
http://www.asoc.org/advocacy/antarctic-wildlife-conservation/southern-ocean-fisheries [accessed 20/05/2015].

National Geographic (2020), Biggest ice sheet on Earth more vulnerable to melting than thought  Available from: https://www.nationalgeographic.com/science/2020/07/east-antarctic-ice-sheet-more-vulnerable-to-melting-than-thought/