BPRC Scientist Delivers 2008 State of the Climate Report

Posted by: Michael Seufer

Despite an abnormally cold winter across the southern half of Greenland, that led to substantially higher west coast sea ice thickness/concentration*, record setting summer temperatures around Greenland and a particularly intense melt season across the northern ice sheet promoted by abnormally cloudy conditions and warm air advection, led 2008 Greenland climate to be marked by continued ice sheet mass deficit and floating ice disintegration.

The 32 widest marine terminating glaciers lost 184.1 km2 of mostly floating ice in 2008 as compared to end of summer 2007, a net loss equivalent with more than two times the size of Manhattan Island, New York. Floating ice shelf disintegration of 63 km2 and 21.5 km2 at the north Greenland Petermann Glacier and Zachariæ Isstrøm, respectively, coincided with abnormally high melt intensity across north Greenland and mimics ice shelf losses along northern Canadian territories. The 2008 Greenland floating ice area loss was 3 x that of the previous summer and 1.7 times greater than the trend (R = -0.98) since whole island observations began summer 2000.

The fraction of precipitation that fell as rain instead of snow, surface melt water production, and melt water runoff were 60-85% above normal (1971-2000). Despite 6-9% (39-50 Gt) more snow accumulation than normal, concentrated along the eastern ice sheet, the surface net mass balance was substantially (53-145 Gt) below normal. Amplified melting led to abnormally low surface reflectance anomalies, further amplifying melt in a positive feedback loop. Much of the surface mass balance anomaly was concentrated near the ice sheet margin where melt rates are largest as is inter-annual variability.

Upper air sounding data indicate a continued pattern of lower tropospheric warming and lower stratospheric cooling 1964-onward. Satellite derived surface melt intensity and extent/duration indicate abnormally intense melt across the northern ice sheet and below equilibrium line altitude (ELA) along the western ice sheet. Less melting than normal is evident above ELA. * - leading dogsledder O.J. Hammeken of the Uummannaq settlement to joke "Global Warming has been cancelled."