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+ocean) temperature reconstructions agree closely. However, trends in four commonly used SST datasets show first-order differences, with 1982-2022 60°S to 60°N trends ranging from 0.09-0.17 °C per decade. These large discrepancies are perplexing given the agreement between global temperature datasets and the fact that 70% of Earth’s surface is covered by ocean, but are legible upon recognizing that global temperature datasets use SST fields whose trends agree more closely than those of the above 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. We discuss some of these findings’ wide implications for understanding the character and impacts of global warming.