The Arctic is a focal point for some of the most profound impacts of climate change. One of the world's top ice experts, Peter Wadhams of Cambridge University, calls the situation a "global disaster", suggesting ice is disappearing faster than predicted and could be gone within as few as four years.

 

"The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer," he told the U.K.'s Guardian.

Over the past 30 years, permanent Arctic sea ice has shrunk to half its previous area and thickness. As it diminishes, global warming accelerates. This is due to a number of factors, including release of the potent greenhouse gas methane trapped under nearby permafrost, and because ice reflects the sun's energy whereas oceans absorb it.