Positive feedback.

[Workingman]

No, not the type where where a boss might ask a customer how one of his employees performed and to be told he did a great job. The positive feedback at hand is the one where a change to a situation impacts on the original situation, making it worse, which forces another change, and so it goes.... into a positive feedback loop that runs out of control.

Climate scientist now believe we are at the tipping point where another 1C increase in global temperatures will trigger the loop. It will start by releasing 55bn tonnes of CO2 into the atmosphere from the land due to the increased activity of micro organisms in the soil. This will cause accelerated melting of land based ice exposing more and more land able to produce more CO2.

Scientists have been worried about positive feedback for ages and now, after many field tests in N. America, Europe and Asia, they have come to the conclusion that the tipping point is as near as 2050. Given recent rises in CO2 past 400ppm they might want to revise the date to some time earlier.

[Suff]

Yep one of the big feedbacks is the loss of the Arctic Ice Cap in summer. The Ice cap, during the daylight months, is worth about 0.5C of cooling just by reflecting sunlight away from the planet back out into space. This is called the ice albedo.

The loss of the Arctic Albedo has been long in the making but likely to be very short in it's demise.

Another step change on the road to oblivion.