Arctic as the ‘radiator fins’ of Earth in a warming climate

Abstract

Earth radiates thermal radiation to balance the solar radiation it receives. Central to understanding climate change is how the radiation energy budget adjusts both globally and locally to external and internal forcing. In the past eighteen years, satellite observations reveal a distinct positive trend of the Earth thermal radiation in the Arctic, which acts to radiate excess heating accumulating in the climate system to the space during global warming, i.e., a radiator fin region in a warming climate. Compared with other regions such as the tropics, the prominent trend in the Arctic results from a stronger surface and atmospheric warming and a less offsetting greenhouse effect of water vapor. Spectral decompositions further show the increase of thermal emission in the Arctic mainly originates from the far-infrared and mid-infrared window region and affirms the unbalanced radiative responses to temperature and humidity changes in these two spectral regions account for the unique thermal radiation trend in the Arctic.