Evolution of land surface air temperature trend

The global climate has been experiencing significant warming at an unprecedented pace in the past century(1,2). This warming is spatially and temporally non-uniform, and one needs to understand its  evolution  to better evaluate its potential societal and economic impact. Here, the  evolution of global  land surface air temperature trend  in the past century is diagnosed using the spatial-temporally multidimensional ensemble empirical mode decomposition method(3). We find that the noticeable warming (>0.5 K) started sporadically over the global  land  and accelerated until around 1980. Both the warming rate and spatial structure have changed little since. The fastest warming in recent decades (>0.4 K per decade) occurred in northern mid-latitudes. From a zonal average perspective, noticeable warming (>0.2 K since 1900) first took place in the subtropical and subpolar regions  of  the Northern Hemisphere, followed by subtropical warming in the Southern Hemisphere. The two bands  of  warming in the Northern Hemisphere expanded from 1950 to 1985 and merged to cover the entire Northern Hemisphere.