Polar pressures

The retreat of Arctic summer sea ice has been dramatic in recent years as recorded by satellite images. But it also appears that the thickness of ice has also experienced equally significant shrinkage. Most computer models predict ice-free summer conditions by 2040 to 2100 but real conditions appear to be moving faster than this. The British Catlin Arctic Survey, which got underway in February, is attempting to gather key new data about the state of the ice in winter and early spring, when the ice reaches its greatest extent. The expedition is making measurements of ice thickness along more than a 1,000 kilometre track from northern Canada to the North Pole. It is hoping to give scientists the very latest 'ground truth' to better inform computer models and their interpretation of the observations coming from satellites. " No other information on ice thickness like this is expected to be made available to the scientific community in 2009, " said Wieslaw Maslowski, a science adviser to the survey, who is affiliated to the US Navy Department of Oceanography at Features the Postgraduate School in Monterey, California. He will use the Catlin observations and the latest meteorological data with an Arctic ice model. " It is commonly agreed in the community that the ice thickness distribution at the spring determines the amount of summer melt occurring in the middle of September, where we reach the minimum ice extent based on satellite observations, " he said. The team, unsurprisingly, have met many physical problems in their expedition. After failure with their portable radar Sprite, the instrument that measures the thickness of the ice, and a fault with the SeaCat probe, a device that measures the water The Arctic ice is thinning and tourists are presenting a growing problem in the increasingly fragile Antarctic environment. Nigel Williams reports. In depth: The Catlin Arctic Survey is finding ice thinner than expected.