Update of Greenland Ice Sheet Mass Loss: Exponential?

• Main Authors: James Hansen, Makiko Sato
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2012
• Subjects: Antarctic; Greenland; The Antarctic; Antarc*; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.397.3177; http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf

Shepherd et al. (2012) provide an update of the mass loss by the Greenland ice sheet (and the Antarctic ice sheet). They compare several analysis methods, achieving a reasonably welldefined consensus. The data is 2-3 years more current than data we employed recently (Hansen and Sato, 2012), so a new look at the data seems warranted. 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 thousands of cities located on global coast lines. However, there seems to be little political or public interest in what happens next century and beyond, so reports of the IPCC (Intergovernmental Panel on Climate Change) focus on sea level change by 2100, i.e., during the next 87 years. IPCC (2007) suggested a most likely sea level rise of a few tens of centimeters by 2100. Several subsequent papers suggest that sea level rise of ~1 meter is likely by 2100. However, those studies, one way or another, include linearity assumptions, so 1 meter can certainly not be taken as an upper limit on sea level rise (see discussion and references in the appendix below, excerpted from our recent paper). Sea level rise in the past century was nearly linear with global