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On thin ice

The thickness and area of summer sea ice is shrinking dramatically. Scientists link this to global warming. They have run climate models which predict the sea ice disappearing in a hundred, fifty, or even thirty years. Scientists need comprehensive data in order to predict more accurately. The results from the European Spave Agency's Cryosat Project help to inform the climate models.

Global warming

The Polar Regions are more susceptible to climate change than other areas of the world. In the Arctic large areas of snow and ice reflect heat from the sun, and keep this region cool. As temperatures rise over the globe, the ice and snow is melting, leaving bare land and open dark water which absorbs the sunlight. This is making the region warmer, causing changes in wind and water currents, effecting weather around the world.

The polar seasons dictate the forming and melting of sea ice. Traditionally the summer melt season begins in March and ends sometime during September. Now the melting season is growing longer and the sea ice minimum is occurring later. Sea ice minimum is when the sea ice extent is at its lowest.

The extent of sea ice in late winter is 14-16 million square kilometres. Research found that:

last winter the average thickness of sea ice over the whole Arctic fell by 26 cm (10 per cent) compared with the average thickness of the previous five winters, but sea ice in the western Arctic lost around 49cm of thickness in winter 2007/08

quote from NERC press release 28.10.08 - research reported in Geographical Research Letters

According to the US National Snow and Ice Data Centre, in 2007 the summer sea ice melt was the lowest since satellite records began thirty years ago. The Centre calculates that sea ice is receding by -11.7% a decade.

Adventure science

Although measurements from satellites, submarines and autonomous buoys, are useful, the data is limited in measuring the thickness and extent of Arctic sea ice. The change in the extent of the ice is easier to record than the thickness, and satellites are not able to distinguish between snow and ice. The only way to get this information is to go there, and the best time to do so, is in winter and early spring when the ice is at its greatest extent. At this time of year the sun is down, for most of the day, and temperatures can be as low as minus 50°C. The people with the most experience of such gruelling conditions are Arctic explorers.

The Catlin Arctic Survey, a major scientific expedition, set out in February 2009, to measure the depth (thickness) and density of the Arctic Ocean ice. This important expedition combined science and polar exploration.

A pioneering feat of human endurance combined with a scientific endeavour

Pen Hadow, Polar Explorer and Catlin Arctic Survey Leader

Supported by scientists, the team of three, led by Arctic explorer Pen Hadow drilled cores or holes of snow and ice, to measure the depth, and record the temperature of the sea below the ice. Warmer southern waters are moving into the Arctic Basin and melting the ice from underneath.

This was the first time that so much surface based information had been collected in this way. They captured around 16,000 observations, taking 1500 measurements of the thickness of the ice and snow as well as its density. This is a valuable set of data that has been collected for scientists. Scientists hope to provide policy makers with improved forecasts, so governments can take appropriate action.

Find out more about some scientific expeditions in the Arctic:

There is more information in the climate change section.

 

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