Thursday, September 07, 2006

Antarctica feels the heat

A new paper published by the Geophysical Research Letters suggests that Antarctica has been getting gradually warmer for the past 150 years, despite indications that the continent cooled considerably during the 1990s. Geophysical Research Letters is the peer-reviewed publication of the American Geophysical Union (AGU). The AGU is an international organisation despite the name and boasts a membership of 41,000 geophysicists in 130 countries.

The new study sheds light on recent cooling in Antarctica and on the complexities of the icy continent's climate. Scientists collected ice cores from five different areas of the continent. They studied oxygen and hydrogen isotopes in the cores to develop the first reconstruction of Antarctic temperature records for the last 150 years. They show the average Antarctic temperatures have risen about 0.2 degrees Celsius in 150 years. This is despite the 1 full degree cooling that occurred in 1990s. The 1990s cooling is at odds with other evidence emerging from the polar region. In 2005 scientists reported that 90 percent of the glaciers of the Antarctic Peninsula are in retreat and melting into the sea. Two separate studies from climate researchers and the space agency NASA showed the glaciers are flowing into Antarctica's Weddell Sea, freed by the 2002 breakup of the Larsen B ice shelf. In March this year, another study confirmed that the Antarctic ice sheet has lost significant mass in the past three years. The sheet contains 90 percent of the planet's ice and is losing 150 cubic kms of ice annually.

Antarctica snapped off from the ancient supercontinent of Gondwana some 40 to 25 million years ago. Cast off, it drifted southwards towards the pole and its flora succumbed to the cold. The continent became icy in the last 15 million years and lost all its remaining trees. It is now the coldest place on the planet. It is much colder than its cousin in the Arctic due to Antarctica’s height (3km above sea level) and its land surface (the North Pole is in the middle of an ocean). Near the South Pole itself, temperatures reach a minimum of -90 °C in the winter. It is a positively balmy 30 degrees warmer in the summer months.

Politically the continent is governed by the 1959 Antarctic Treaty. The Treaty was signed by 12 countries: Argentina, Australia, Belgium, Chile, France, Japan, New Zealand, Norway, South Africa, the USSR, the UK and US. The terms of the treaty are that military and nuclear activities are prohibited, scientific co-operation is encouraged and no territorial claims are recognised. Many nations have overlapping claims which are on hold while the Treaty stays in place. The US Marshals Service made history in 1989 by being the first law enforcement agency on the continent. U.S. Marshals now greet all visitors to McMurdo Station with a lecture and a warning that serious crimes committed on the continent by Americans can be prosecuted in the United States.

The biggest immediate threat to Antarctica is not climate change or crime but tourism. The number of people visiting the continent has increased six-fold in the last 15 years. According to the Antarctic and Southern Ocean Coalition (ASOC), just under 5,000 tourists visited Antarctica in the 1990-91 summer. In 2003-4 the figure rose to 24,000 and is expected to rise to 30,000 this year under the influence of the popular documentary film “March of the Penguins”. And next Summer tourism moves on to a new level. A new US-based cruise ship, The Golden Princess, is 10 times bigger than cruise ships plying Antarctica's waters, and can carry 3,800 passengers and crew. Scientists, worried about the potential for invasive species, are asking the US to carry out an environmental impact assessment before it sails. However, this is unlikely. The ship is registered in Bermuda which is not party to the Antarctic Treaty system. Humanity is starting to exercise its control over the last inhospitable land on the planet.

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