Should We Expect Each Year in the Next Decade (2019–28) to Be Ranked among the Top 10 Warmest Years Globally?

Data. We utilize the monthly operational version of global surface temperature time series produced by the NOAAGlobalTemp analysis. NOAAGlobalTemp includes land-based nearsurface air temperatures from the Global Historical Climatology Network Monthly dataset (GHCN-M; version 4.0.1) and sea surface temperatures (SSTs) from the Extended Reconstructed Sea Surface Temperature dataset (ERSST; version 5). The operational monthly time series are accessible online. 1 Prior to mid-2019, the operational version of NOAAGlobalTemp was based on GHCN-M version 3.3.0 and ERSST version 4. We repeated our analyses using this previous operational version of NOAAGlobalTemp, and the results were virtually indistinguishable from those presented here. We also utilize the oceanic Nio index (ONI), a 3-month running average of SST anomalies in the Nio 3.4 region. The current operational version of ONI is produced by NOAA's Climate Prediction Center using ERSST, version 5, and is also accessible online. 2