Long‐term evolution of global sea surface temperature trend

The ocean plays an essential role in regulating global and regional climate, which is mainly achieved through sea surface temperature anomaly (SSTA) changes. Studies on global sea surface temperature (GSST) are primarily carried out under linear assumption, which is not capable of fully revealing the evolution characteristics of sea surface temperature (SST) due to the non-linear and non-stationary nature of the SST. Here, the evolution of the GSST trend in the past century is investigated by using an adaptive and local spatial-temporally multidimensional ensemble empirical mode decomposition method. The results show that the global ocean has been warming except for the subpolar North Atlantic, the equatorial central Pacific, and the Southern Ocean in the Pacific sector. The equatorial central Pacific turned from cooling to warming around the middle of the last century made it one of the fastest-warming regions in recent decades with other regions located in the Arctic Ocean and the western-boundary current regions and their mid-latitude extensions in both hemispheres. The strongest warming during recent decades is found in the Arctic Ocean, east of the continents in the northern hemisphere, the entire Indian Ocean, and especially in the tropical Pacific Ocean. From a zonal average perspective, warming (>0.1 K since 1900) first took place in the subtropical regions of the Northern Hemisphere and 50 degrees S of the Southern Hemisphere almost simultaneously around 1910, then followed by the subpolar warming in the Northern Hemisphere. The first two bands of warming both expanded equatorward leading to the fast warming of tropical oceans, especially for the Pacific Ocean.