In his latest posting, James Hansen looks at ice sheet loss in Greenland and Antartcia, and warns of the possiblility of an exponential ice sheet loss rate.
Posing the question, he asks:
A crucial question is how rapidly the Greenland (or Antarctic) ice sheet can disintegrate in response to global warming. Earth's history makes it clear that burning all fossil fuels would cause eventual sea level rise of tens of meters, thus practically wiping out thosands of cities located along global coast lines. However, there seems to be little political or public interest in what happens the next century or beyond, so reports of the IPCC (Intergovernmental Panel on Climate Change) focus on sea level change by 2100; i.e. during the next eighty-seven years.
He adds an alarming graph, looking at the possibilities mathematically, charted against known satellite records, but writes that exponential ice sheet loss — although looking all too likely — is not yet certain.
"This shows that fossil fuel companies have five times more carbon in their reserves than even the most conservative governments think would be safe to burn."