Monday, April 16, 2018, 12:15PM - 1:15PM
Sievers conference room, SEEC S228
4001 Discovery Drive, Boulder
It has been well documented that climate warming is greater in the Arctic than elsewhere. However, it is still poorly understood how climate changed over different permafrost zones and its potential impacts on permafrost thermal dynamics. In this study, we investigated changes in air temperatures, especially seasonal air temperatures, over different permafrost regions in the Northern Hemisphere using the Climate Research Unit (CRU) gridded dataset from 1976-2016. The primary results indicated that permafrost regions as a whole experienced a warming at 0.36, 0.41, and 0.46 °C/decade in mean annual maximum, mean, and minimum air temperatures, respectively, which were 16%, 32%, and 44% higher than the corresponding trend in non-permafrost regions. More importantly, strong increases occurred in cold months and nighttime over continuous permafrost zone, exceeding 0.72 °C/decade in spring and autumn, while summer air temperature had relatively small increase or no statistically significant trends. As a result, decrease of air freezing index by 529 °C-day would result in a large permafrost temperature increase in continuous permafrost zone over the past four decades. This may explain the observed evidence that increase of cold permafrost temperature was greater than that of warm permafrost, while active layer thickness had little or no change during the past several decades.
Free and open to the public.