Pen Hadow, the first man who walked to the North Pole, is leading a ground-breaking expedition to measure the thickness of the Arctic sea ice.
Green Guardian is a sponsor of the Catlin Arctic Survey, which scientists hope will provide accurate data on how fast the polar ice-caps are melting.
All pictures by Martin Hartley (c)
The Catlin Arctic Survey team prepared for their expedition by training in the Canadian High Arctic
Scientists at Polaris Camp