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Hydrology and Terrestrial Cryosphere Summary

Section Coordinator: Marco Tedesco

The City College of New York, New York, NY, USA5

November 15, 2011

The Hydrology & Terrestrial Cryosphere section of the 2012 Arctic Report Card documents consistent and widespread evidence for continuing change in snow cover, glaciers and ice caps, the Greenland ice sheet, permafrost, lake ice, river discharge and river biogeochemistry. On the Greenland ice sheet and on most glaciers and ice caps elsewhere in the Arctic, the period 2010-2011 was characterized by a negative mass balance, i.e., more snow and ice was lost, primarily by surface melting and runoff, than snow was gained. The western slope of the Greenland ice sheet in particular experienced a significant increase in surface melting, amplified by albedo feedback and, in 2011 and 2010, by below-normal summer snowfall. GRACE satellite gravity solutions show that the mass loss from the entire ice sheet during the 2010-2011 balance year was -430 Gt, the largest annual loss in the GRACE record (2002-present) and equivalent to a eustatic sea level rise of 1.1 mm. Mass losses in summer 2011 are linked to positive surface and upper air temperature anomalies similar to those observed in 2007 and 2005.

Below-average snow extent during spring 2011 is consistent with a decline observed since the 1970s, and continues an accelerated decrease since 2006. June snow cover extent in Eurasia was the lowest since the start of the satellite record in 1966. Positive snow water equivalent (SWE) anomalies in the North American Arctic in 2011 were the third highest since the start of the time series in 1980. Despite this, spring snow cover extent and duration were below-average across both the North American and Eurasian sectors of the Arctic due to positive air temperature anomalies in May and June, the two primary months for snow melt. A general increase in permafrost temperatures observed in Alaska, northwest Canada, Nordic countries, and in Siberia during the last several decades continued in 2010-2011. New record high permafrost temperatures at 20 m depth were measured in 2011 at all observatories on the North Slope of Alaska, where measurements began in the late 1970s. However, a slight decrease (by as much as 0.3°C) in Interior Alaska has been observed during the last three years.

Lake ice cover duration, largely influenced by air temperature changes, was shorter by as much as 4-5 weeks in 2010-2011 compared to the 1997-2010 average for the eastern Canadian Arctic. River discharge into the Arctic Ocean during 2010 was close to the long-term (1936-2009) mean for the six largest Eurasian Arctic rivers and the four large North American Arctic rivers. Preliminary estimates for 2011, based on modeling and some observations, indicate river flows to the Arctic Ocean during January to July were significantly lower than the long-term mean. In 2010, dissolved organic carbon (DOC) flux from five of the six largest Arctic rivers was less than the 2003-2009 average. Combined DOC flux from all six rivers peaked in 2007, but has been lower each year since, closely tracking the downward trend in their combined discharge.

 

Photograph of an Arctic researcher and his snowmobile during the 2011 Arctic Observing Network (Snownet) project in Alaska. Image Credit: Mark Serreze, NSIDC. From NSIDC photo & Image Gallery.