Observed warming in cold anticyclones

Abstract

During the past half-century, we find that the observed surface warming trend in the northern hemisphere, averaged across grid cells that contain at least 90% of the total monthly data, has been 0.051°C decade-1. On a seasonally weighted basis, a relatively small area (12.8%) contributed over half of the annual warming, and in the winter 26% of the area accounts for 78% of the warming. Our analysis demonstrates that this warming is almost exclusively confined to the dry, cold, anticyclones of Siberia and northwestern North America. The consequences of this type of regional warming are different than those associated with other regional warming scenarios. The spatial pattern of observed warming is not coincident with that projected by many of the leading general circulation models, including those featured in the 1996 Report of the Intergovernmental Panel on Climate Change.