I don't know what's up with Greenland, but it is very difficult to find the numbers for the 2008-2009 mass balance loss. The report below, in the last figure, gives only two-dimensional figures for loss of some of the outlet glaciers. Maybe they are waiting for the meeting of the AGU in December or for later in November before Copenhagen -- I sure am not privy to the reasons for this lack of information.
An abnormally cold winter across the southern half of Greenland led to substantially higher west coast sea ice thickness and concentration. Even so, record-setting summer temperatures around Greenland, combined with an intense melt season (particularly across the northern ice sheet), led the 2008 Greenland climate to be marked by continued ice sheet mass deficit and marine-terminating ice disintegration.
|Figure G1. (a) winter and (b) summer near-surface (2 m) air temperature anomalies with respect to the 1971–2000 base period, simulated by Polar MM5 after Box et al. (2006). (Click each image for larger version) |
|Table G1. 2008 Summer 700-hPa temperature and winter precipitation anomalies (relative to 1948–2008 NCEP reanalysis means) for glaciated regions of the Arctic (excluding Greenland). Inferred sign of surface mass balance is based on comparison of historical mass balance records for each region with NCECEP reanalysis temperature and precipitation anomalies. Anomalies in melt duration and the timing of melt onset and freeze-up (relative to 2000–2004 climatology) derived from QuikSCAT data. For timing, negative anomalies indicate an earlier-than-normal date. |
Surface melt extent and duration
Passive (SMMR and SSM/I, 1979–2008) and active (QuikSCAT, 2000–08) microwave remote sensing (Bhattacharya et al. 2009, submitted to Geophys. Res. Lett.; Liu et al. 2005) indicate abnormally high melt duration over the north and northeast ice sheet and along the east and west coasts above Greenland’s most productive three outlet glaciers in terms of ice discharge into the sea: Kangerlussuaq, Helheim and Jakobshavn (Fig. G2). Lower-than-normal melt duration is evident over much of the upper elevations of the ice sheet. New records of the number of melting days were observed over the northern ice sheet, where melting lasted up to 18 days longer than previous maximum values. Anomalies near the west coast are characterized by melting up to 5–10 days longer than the average (Tedesco et al. 2008).
Polar MM5 climate data assimilation model runs spanning 51 years (1958–2008), calibrated by independent in situ ice-core observations (Bales et al. 2001, Mosley-Thompson et al. 2001, Hanna et al. 2006) and ablation stakes (van de Wal et al. 2006), indicate that 2008 total precipitation and net snow accumulation was slightly (6%–8%) above normal (Table G2). In accordance with a +0.9 °C 2008 annual mean surface temperature anomaly, the fraction of precipitation that fell as rain instead of snow, surface meltwater production, and meltwater runoff were 142%–186% of the 1971–2000 mean. Consequently, and despite 6%–9% (39–50 Gt) more snow accumulation than normal, the surface net mass balance was substantially (145 Gt) below normal. 2008 surface mass balance ranked ninth-least positive out of 51 years (1958–2008).
|Table G2. Greenland ice sheet surface mass balance parameters: 2008 departures from 1971–2000 average (adapted from Box et al. 2006). Estimates by Hanna et al. (2008) are included for comparison. |
Surface mass balance anomalies indicate a pattern of increased marginal melting with noteworthy departures in excess of 1-m water equivalence per year from normal across the northern ice sheet (Fig. G4). The pattern of steepening mass balance profile is consistent with observations from satellite altimetry (Zwally et al. 2005) and airborne altimetry (Krabill et al. 2000), satellite gravity retrievals (e.g., Luthcke et al. 2006) and climate projections (Solomon et al. 2007).
Marine-terminating glacier area changes
Daily surveys of Greenland ice sheet marine terminating outlet glaciers from cloud-free MODIS imagery (http://bprc.osu.edu/MODIS/) indicate that the 34 widest glaciers collectively lost 106.4 km2 of marine-terminating ice between the end of summer 2008 and the end of summer 2009 (Figure G4). This is equivalent to an area 20% larger than Manhattan Island (87.5 km2), New York. The largest individual glacier losses are observed at: Humboldt (-37 km2); Zachariae Isstrom (-31 km2); and Midgard (-16 km2). The 2000-2009 rate (106 km2) has been linear (R = −0.98) despite the fact that a few individual glaciers exhibit erratic annual net ice area changes. The cumulative area change from end-of-summer 2000 to 2009 is −990 km2, an area 11.3 times that of Manhattan Island.
|Figure G4. Cumulative annual area changes for 34 of the widest Greenland ice sheet marine-terminating outlets. |
Link to report on Greenland: http://www.arctic.noaa.gov/reportcard/greenland.html