Polar ice melt and sea level rise: earth climate in uncharted territory

The extreme rate of greenhouse gas forcing, rising at ~2 ppm CO2/year, leads potentially to tipping points such as high-rate methane release from permafrost and Arctic sediments, and the potential collapse of the North Atlantic Thermohaline Stream.

Doubts are often raised among climate scientists whether the Greenland and West Antarctic ice sheets can survive the 1.8 – 4.0 C temperature rises projected by the IPCC-2007 [2], leading to meters-scale sea level rise.

The increase in frequency of extreme weather events manifests a rise in the atmosphere/ocean energy level. Global temperature rise, ice melt and sea level rise lag behind the rise of GHG forcing of about ~2 Watt/m2 [2] (Figure 4). The precise time scale of this lag remains unknown.

The Earth climate is entering uncharted territory.

[1] http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf

[2] IPCC 2007

[3] http://data.giss.nasa.gov/gistemp/graphs/

[4] http://data.giss.nasa.gov/gistemp/maps/

[5] Rahmstorf et al., 2007. http://www.sciencemag.org/content/315/5810/368.short

[6] Pfeffer et al., 2008. http://climatechangepsychology.blogspot.com/2008/12/w-t-pfeffer-j-t-harper-s-oneel.html

[7] Vermeer and Rahmstorf, 2009. Vermeer: Global sea level linked to global temperature, Proc. Natl.Acad. Sci., 106, 21527-21532.

[8] Alley, 2010. Alley, R.B., 2010: Ice in the hot box—What adaptation challenges might we face? 2010 AGU Fall Meeting, December 17, U52A-02.