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Jim Hansen's icemelt scenario confirmed

The feedback mechanism Jim Henson predicted in 2007 is happening now

Dr. Hansen predicted that a "fast-feedback" mechanism would lead to ice sheet disintegration: since proven to be correct. This mechanism raises the fear that ice melting would lead to a non-regular sea-level rise, and far beyond that predicted by the cautious IPCC reports.

Icemelt
Icemelt between 1989 and 2011, Bear Glacier, Alaska

In a famous 2007 paper, Dr. Hansen demonstrated through paleoclimate data that the ice sheets of the polar regions may not support the IPCC prediction of a 59 cm rise in sea level by the end of the 21st century.

Fast-Feedback acceleration of ice melt

Geological studies suggest that ice does not melt in a linear fashion, but is more likely to change state in sudden 'flips'. One shocking possibility is that sea levels may rise by far more than predicted. When temperatures rise by 3°C, there is geological evidence to fear a 25m or more rise in sea levels. This is not an unknown occurrence for the planet - it happened as recently as 3.5 million years BP (Before Present).

Dr. Hansen takes pains to emphasise that the report is not meant to be alarmist, and acknowledges that there are many parameters involving broad ranges of uncertainty. One of these is the ice sheet response time. However, since the 2007 report, large parts of the ice shelf have in fact broken off far earlier than expected, giving credence to the propositions.

Icemelt
Pine Island Glacier calving, Antarctica, 2013

Dr. Hansen has been very outspoken about the degree of alarm people should feel about climate change, and the gap between this danger and the political and economic responses. In 2008 interviews on TV and the printed press, Dr. Hansen proposed equating the actions of people, such as fossil fuel CEOs, in their deliberate promulgation of false information, to any other crimes against humanity.

"Storms of My Grandchildren" is his first book, published in 2009.

His 2012 TED Talk is entitled: Why I must speak out about climate change.

Article by Andrew Bone, December 31, 2015

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