Amplification of and Trends in Arctic Surface Temperature
Friday, 19 December 2014: 2:10 PM
The earliest signals of a climate change are being observed in the Arctic where warming has been amplified primarily on account of ice-albedo feedbacks associated with the high reflectivity of snow and ice. Because of general inaccessibility, there is a paucity of in situ data and hence the need to use satellite data to observe the large-scale variability and trends in surface temperature in the region. The sensor with the longest record has been the Advanced Very High Resolution Radiometer (AVHRR) that has provided continuous thermal infrared data since 1981. The primary source of error in the data is cloud masking because of similar signatures of clouds and snow/ice covered surfaces. The temperatures derived from the Moderate Resolution Imaging Spectroradiometer from 2000 to the present were used as the baseline for the study and to enhance the AVHRR data. SSTs from the Advanced Microwave Scanning Radiometer were also used for assessments of accuracy and short term variability in ice free ocean regions. These three data sets were used in conjunction with meteorological station data to quantify changes in surface temperature over the pan-Arctic region. Our results show an average warming rate of 0.6°C per decade in the Arctic (>64 °N) from 1981 to 2013 which is 3 times that of about 0.2°C per decade globally for the same period which in turn is more than 2 times the global warming rate from 1900 to 2013. The spatial distribution of warming is, however, not uniform with the trends varying from around 0.2oC/decade in Eurasia to about 0.7oC/decade in Greenland. Some regions of the Arctic such as Siberia and the Bering Sea show moderate cooling but caused in part by anomalously warm values in these regions in the 1980s. Also, the average SST in the Arctic basin is observed to be increasing and is highly correlated to changes in the sea ice cover.