New atlas shows unseen world under polar ice
An unseen world of canyons, lakes and mountains buried under the polar ice is detailed in the new edition of the Times ComprehensiveAtlas of the World.
New maps of the polar regions replace near-blank whiteness with features hidden by ice sheets in the Antarctic and Arctic, and also show the dramatic decline in Arctic sea ice in recent decades as the region is affected by rising global temperatures.
The sub-ice maps use bedrock data to show physical features such as the Antarctic's Gamburtsev Subglacial Mountains, which are as large as the Alps but completely covered in ice.
In the Antarctic, the map also shows huge trenches buried under glaciers, including the Bentley Subglacial Trench, which reaches a depth of 8,188ft (2,496m), and the location of Lake Vostok, lying close to 2.5 miles (4km) under the ice sheet.
The Astrolabe Trench, which contains the thickest ice in the world, is also featured on the map.
At the other end of the world, the map shows Greenland's "mega canyon", which is more than 470 miles (750km) long and 2,600ft (800m) deep, running north to south under the ice sheet.
The canyon, which was discovered in 2013 and is thought to be older than the ice sheet that covers it, is unnamed, although Greenland's "Grand Canyon" or "Grand Canyon of Greenland", have been proposed, theAtlas's publishers said.
Peter Fretwell of the British Antarctic Survey said: "It's very important to know how much ice there is and what the topography of the bed looks like, as this is one of the main controls on how quickly ice sheets melt with climate change."
He said the data in the survey of the Antarctic bedrock was a key component in scientific models that tried to predict future sea level rises.
"As the world warms with increasing greenhouse gas emissions Antarctic ice will start to melt and cause global sea levels to rise, but the speed and amount of sea level rise is very dependent upon the bed-topography under the ice sheet."
The new edition of the Times ComprehensiveAtlas of the World also has a map which includes long-term trends in Arctic sea ice cover, showing the average summer sea ice extent from 1981 to 2010, as well as the record low minimum cover in 2012.
It also shows the minimum extent of the ice last year, 18% lower than the 30-year average, using data sourced from the National Snow and Ice Data Centre in the US which tracks polar ice cover.
Arctic sea ice melts each summer, reaching its lowest extent in September, and the changes to the sea ice cover are seen by scientists as a sensitive indicator of the warming climate.
Walt Meier, research scientist at the Cryosphere Science Branch, Nasa Goddard Space Flight Centre in the US, said: "End of summer sea ice extent averages 40% less than it used to be in the early 1980s.
"The ice is also substantially thinner, about half the thickness on average than during the 1980s. The loss of sea ice results in more energy being absorbed in the Arctic, contributing to amplified warming compared to the rest of the globe."
The previous edition of the TimesAtlas, published in 2011, was hit by controversy amid claims by the publishers that 15 per cent of Greenland's ice had melted in little over a decade, an assertion they were forced to admit was "incorrect".
A reworked map of Greenland also had to be produced after scientists said numerous glaciers could be found where theatlas showed ice-free conditions and the emergence of new land.
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