Thursday, September 06, 2012

Climate change: Positive feedback

By now everyone should have heard about this year's record low for Arctic sea-ice cover. The bad news is that its got even worse, dropping below 4 million square kilometers today - and there's still a week to go. And this isn't just an abstract thing - it is likely to have a severe effect on the global climate:

Loss of Arctic ice is effectively doubling mankind's contribution to global warming, ice scientist Professor Peter Wadhams has told BBC Newsnight.

White ice reflects more sunlight than open water, acting like a parasol.

Melting of white Arctic ice, currently at its lowest level in recent history, is causing more absorption.

Prof Wadhams calculates that this increased absorption of the sun's rays is "the equivalent of about 20 years of additional CO2 being added by man".

The precise magnitude of that effect will be up for some quibbling - but the direction certainly isn't. We're entering the age of positive feedback, where climate change pushes more climate change which pushes more climate change. Under that ice is billions of tons of methane, which dribbles out faster as the Arctic warms. Which means even more climate change... if we don't stop this, we could be living in a very warm future - and it may already be too late.