Our directory of things of interest

University Directory

Arctic ice sheet paradox resolved

  • Written by  Olivia Edward
  • Published in Polar
Arctic ice sheet paradox resolved NASA
01 Oct
A team of French scientists has used sediment cores dating back 70,000–80,000 years to resolve a long-standing paradox about the formation of the Arctic ice sheet 

Over the past two million years, cyclical variations in the amount of solar energy reaching the Earth have caused it to experience a series of long glacial periods separated by short, warmer intervals known as interglacials. The last glacial period, which ended 12,000 years ago, began 80,000–70,000 years ago.

At the beginning of this period, sea levels dropped by 80 metres as large amounts of snow accumulated at high latitudes, eventually leading to the formation of the ice sheet around the North Pole. But cold temperatures are generally associated with dry weather and scarce precipitation – for snow to fall, the weather needs to be humid and the temperature only moderately low, hence the long-standing paradox.

In the present study, researchers analysed marine sediment cores collected off Galicia in Spain and from the Bay of Biscay. They used fossil pollen grains to characterise the temperatures on land and microscopic marine organisms called foraminifera to determine the temperature of the ocean.

The results indicated that during the period under study, water temperatures in the Bay of Biscay remained relatively high, whereas those in mainland Europe gradually fell. The humidity released by the resulting thermal contrast, which was presumably carried northwards by wind, caused the snowfall that formed the polar ice sheet, the researchers believe.

This story was published in the October 2013 edition of Geographical Magazine

Related items

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...


Xavi Bou's artistic visions of flight beguile the eye


Hydropower is considered essential if the world is to reach…


An overlap between populations of grizzly bears and Indigenous groups…


Climate change is having a huge impact on the oceans,…


The first COP26 draft agreement has been released


Marco Magrini explores the complex issue of carbon markets –…


The youth found marching outside the COP26 conference in Glasgow…


Energy day at COP26 was all about coal. Marco Magrini…


The world is reliant on the climate models that forecast…


Geographical editor, Katie Burton, spends the day at COP26: finance…


Lawyers are using the power of the courts to challenge…


Mike Robinson, chief executive of the Royal Scottish Geographical Society…


Will China's climate pledges be enough to achieve Xi Jinping's…