Greenland’s glaciers and the Arctic climate




But scientists cannot pin the Petermann glacier event—or any specific ice breakup—squarely on climate change. There are too many variables that determine exactly when a glacier calves. Box said, “A single cracking event could conceivably be triggered by a seagull, acting like the straw that broke the camel’s back.” Data compiled by Box show that air temperatures in Greenland have risen sharply in the last twenty-five years. The extent of melting and ice retreat has accordingly increased.

Glaciers and sea ice

What do changes in the Greenland Ice Sheet have to do with declining sea ice in the Arctic? Studies show that the ice on land and ice in the ocean are intimately related. The decline in sea ice could speed up ice loss in Greenland. “It is reasonable to speculate that changes in sea ice duration and concentration in the vicinity of glacier fronts should impact their stability,” said Box. “As the sea ice melts, the ocean can be stirred up more by strong Arctic winds and change fjord water circulation and the sub-marine melt regime.”  Winter sea ice also acts as a buttress against glacier ice flow, seasonally slowing the flow speed. An earlier break-up and later freeze-up of sea ice in the fjords may play a role in the ice sheets’ mass balance.


Measurements show that Greenland’s ice does indeed flow into the ocean faster than snow accumulates on the island. This means that sea level is rising—a potential problem for people around the world. “As ice sheets continue to contribute to sea level rise, as expected in climate warming scenarios, the effects will be felt not just in coastal areas,” Box said, “The effects will also be felt globally, where the coastal impacts lead to economic ripple effects.”

For more details and photos of the Petermann Glacier, before and after the 2010 calving, visit Jason Box’s Web site.


Falkner, K. K., et al. 2011. Context for the Recent Massive Petermann Glacier Calving Event. Eos Transactions of the American Geophysical Union 92(14), doi:10.1029/2011EO140001.

Box, J.E. and D. T. Decker, 2011: Analysis of Greenland marine-terminating glacier area changes: 2000-2010. Annals of Glaciology 52(59) 91-98.

Johannessen, O. M., Babiker, M., and Miles, M. W. 2011. Petermann Glacier, North Greenland: massive calving in 2010 and the past half century. The Cryosphere Discussions 5, 169-181, doi:10.5194/tcd-5-169-2011.

Box, J.E., L. Yang, D.H. Bromwich, L-S. Bai, 2009. Greenland ice sheet surface air temperature variability: 1840-2007. Journal of Climate 22(14): 4,029-4,049, doi:10.1175/2009jcli2816.1.

Box, J.E., I. Bhattacharya, J. Cappelen, D. Decker, X. Fettweis, K. Jezek, T. Mote, M. Tedesco, 2010. Greenland [in “State of the Climate in 2009”]. Bulletin of the American Meteorological Society 91(6): S79-S82.

Howat, Ian M., and A. Eddy. 2011. Multi-decadal retreat of Greenland’s marine-terminating glaciers. Journal of Glaciology 57(203): 389-396.

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