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Tag: British Antarctic Survey

  • New Study Shows Causes of Antarctic Sea Ice Increase

    Researchers from NASA and the British Antarctic Survey have published a new study that shows changes to Antarctic sea ice drift caused by changing winds are the cause of increases in Antarctic sea ice cover over the past two decades. The results help explain why Antarctic sea ice cover has increased while Arctic sea ice has seen heavy losses.

    The study, published this week in the journal Nature Geosciences, used maps created by NASA’s Jet Propulsion Laboratory (JPL) from more than five million daily ice-motion measurements captured by U.S. Defense meteorological satellites over a period of 19 years. According to researchers, the maps show long-term changes to sea ice drift around Antarctica for the first time.

    “Until now, these changes in ice drift were only speculated upon, using computer models of Antarctic winds,” said Paul Holland, lead author of the study and ocean modeller at the Natural Environment Research Council’s British Antarctic Survey. “This study of direct satellite observations shows the complexity of climate change. The total Antarctic sea ice cover is increasing slowly, but individual regions are actually experiencing much larger gains and losses that are almost offsetting each other overall.

    “We now know that these regional changes are caused by changes in the winds, which, in turn, affect the ice cover through changes in both ice drift and air temperature. The changes in ice drift also suggest large changes in the ocean surrounding Antarctica, which is very sensitive to the cold and salty water produced by sea ice growth.”

    The research shows that the increase in sea ice cover in the Antarctic is the result of larger regional increases and decreases caused by wind-driven changes. The Arctic Ocean is surrounded by land, meaning that changing winds cannot cause its sea ice to expand.

    “The Antarctic sea ice cover interacts with the global climate system very differently than that of the Arctic, and these results highlight the sensitivity of the Antarctic ice coverage to changes in the strength of the winds around the continent,” said Ron Kwok, a senior research scientist at JPL.

    (Image courtesy the British Antarctic Survey)

  • Buried Antarctic Lake Targeted by a New Expedition

    Next month, a 12-man team of scientists, engineers, and support staf will set off for Antarctica on a quest to collect samples from an ancient lake that has been buried for hundreds of thousands of years. The expedition has taken 16 years of planning and development. During the past three years, engineers at the British Antarctic Survey (BAC) and the National Oceanography Centre (NOC) have designed and built a titanium water-sampling probe and a sediment corer that will be lowered through through the three kilometres of antarctic ice the lake is buried under.

    Once the team arrives on-site, and after drilling a three-kilometer hole with a hot-water drill, they will have just 24 hours to sample water and sediments from Lake Ellsworth. After that, the bore hole will re-freeze. The team, led by Martin Siegert, professor of geosciences at the University of Bristol, will be facing temperatures of -25°C on the surface of the West Antarctic Ice Sheet above the lake.

    “For the first time we are standing at the threshold of making new discoveries about a part of our planet that has never been explored in this way,” said Siegert. “Finding life in a lake that could have been isolated for up to half a million years is an exciting prospect, and the lake-bed sediments have the potential to paint a picture of the history of the West Antarctic Ice Sheet in a way that we haven’t seen before. The team’s mission is to get into the deep field and bring back clean, valid samples of lake water and lake-bed sediments, which can be brought back to the UK for in depth analysis.”

    The expedition is going to great lengths to keep the lake from becoming contaminated. Every piece of equipment will be sterilised to space industry standards. The team is hoping to bring up samples sometime in December of this year.

    “This time last year a small advance party transported nearly 70 tonnes of equipment 16,000 km from the UK to the drilling site,” said Chris Hill, program manager at the British Antarctic Survey. “Now, one year later, we will ship another 26 tonnes of equipment on to the continent so that we can complete stage two of this challenging field mission. We set foot on the ice again in October and hope to bring samples to the surface in December 2012 – an historic moment we have all been waiting for.”

    (Photo courtesy the British Antarctic Survey)