When a large outlet glacier of North Greenland (Petermann Gletscher) discharged an ice island four times the size of Manhattan in August of 2010, the United States’ Congress held formal inquiries on its cause within days of the event. Congressmen, scientists, and the global media speculated that this event and concurrent severe droughts in Russia and floods in Asia were tied to record-breaking air temperatures and global warming. Reviewing available data, Johnson et al. (2011) cautioned that most melting of floating ice shelves such as Petermann Gletscher is dominated by physical ocean processes below, not above the ice (Reeh, 2001, Rignot and Steffen, 2008). The National Journal asked me to write an essay to answer the question: “Is Climate Change Causing Wild Weather?” which I answered with a nerdy No, but …. Motivated by questions asked during the congressional hearing, I showed that waters in Petermann Fjord (a) originate from the Arctic Ocean to the north, (b) contain heat of Atlantic origin, and (c) have warmed significantly since 2003 (Muenchow et al., 2011).
Petermann Gletscher from MODIS Terra. Repeat NASA along-glacier flight tracks are shown in the left and middle panels. White line across the glacier are ICESat tracks. Thick black line across the glacier near y = 0 km is the grounding line location from Rignot and Steffen (2008). Dark areas within 2 km off the western wall are mountain shadows.
When I reported here that the same glacier discharged yet another ice island in July 2012, this one “only” twice the size of Manhattan, I was not so sure anymore, that this was merely another extreme event caused by natural processes. Continue reading →
Posted in Global Warming, Greenland, Ice Cover, Ice Island, Petermann Glacier
Tagged climate, glaciers, Greenland, ice island, Nares Strait, NASA, Petermann
Icy Seas 