Global temperature anomaly data come from NOAA's
Global Surface Temperature Analysis (NOAAGlobalTemp),
which uses comprehensive data collections of increased global coverage over land
(Global Historical Climatology
(Extended Reconstructed Sea Surface Temperature)
surfaces. These datasets have data from 1850 to the present. The land and ocean datasets are blended into
a single product to produce the combined global land and ocean temperature anomalies. The available timeseries of
global-scale temperature anomalies are calculated with respect to the 1901-2000 average, while the
mapping tool displays global-scale temperature anomalies with respect to the 1991-2020 base period.
For more information on these anomalies, please visit
Global Surface Temperature Anomalies.