Greenland ice sheet surface air temperature variability: 1840-2007

Meteorological station records and regional climate model output are combined to develop a continuous 168-yr (1840-2007) spatial reconstruction of monthly, seasonal, and annual mean Greenland ice sheet near-surface air temperatures. Independent observations are used to assess and compensate for systematic errors in the model output. Uncertainty is quantified using residual nonsystematic error. Spatial and temporal temperature variability is investigated on seasonal and annual time scales. It is found that volcanic cooling episodes are concentrated in winter and along the western ice sheet slope. Interdecadal warming trends coincide with an absence of major volcanic eruptions. Year 2003 was the only year of 1840-2007 with a warm anomaly that exceeds three standard deviations from the 1951-80 base period. The annual whole ice sheet 1919-32 warming trend is 33% greater in magnitude than the 1994-2007 warming. The recent warming was, however, stronger along western Greenland in autumn and southern Greenland in winter. Spring trends marked the 1920s warming onset, while autumn leads the 1994-2007 warming. In contrast to the 1920s warming, the 1994-2007 warming has not surpassed the Northern Hemisphere anomaly. An additional 1.0°1.5°C of annual mean warming would be needed for Greenland to be in phase with the Northern Hemispheric pattern. Thus, it is expected that the ice sheet melt rates and mass deficit will continue to grow in the early twenty-first century as Greenland's climate catches up with the Northern Hemisphere warming trend and the Arctic climate warms according to global climate model predictions.