Consequential differences in satellite-era sea surface temperature trends across datasets

Global surface temperatures since the 1980s, when near-global satellite-based sea surface temperature (SST) measurements became available, are presumed to be well known. Satellite-era warming trends in four commonly used global (land and ocean) temperature reconstructions agree closely, yet whether SST datasets also agree is unclear. Here we show that trends in four widely used SST datasets show first-order differences, with 1982–2024 60° S to 60° N trends ranging from 0.108 to 0.184 °C per decade. These large discrepancies are perplexing given the agreement between global temperature datasets and the fact that 70% of the surface of the Earth is covered by ocean, but are legible upon recognizing that global temperature datasets use two SST fields whose trends agree more closely than those of the four SST datasets. Considering the trend uncertainty across SST datasets widens the range of plausible global temperature trends and impacts interpretations of recent record global temperatures, with implications for observational and model-based climate studies.