Regions of extremes of decadal surface temperature trends in 1900-1970

Abstract

Surface layer temperature changes occur on various time scales: interannual, decadal, secular. Decades and longer periods are the most important time scales for studying gradual changes in mean hydrometeorological values. This paper is dedicated to assessing the spatial distribution of decadal trends in mean annual surface layer temperature (°C/yr) for successive decades from 1901 to 1970. The source of the initial data is the land+sea series from the HadCRUT5 Analysis version 5.0.2.0 archive, characterizing 5° x 5° latitude-longitude boxes. The resulting maps of the spatial distribution of trends revealed warming and cooling areas with linear dimensions greater than 1000 km, for which the absolute rate of change exceeded 0.1°C/yr. This value is three times higher than the hemispheric average estimates. Such values are referred to as extreme in the paper. In many cases, they are confined to the Arctic zone. The presence of such areas from 1901 to 1970 is a consequence of natural variability in the climate system, as anthropogenic impacts on it were still minor during this period.