Global (left) and European land (right) average near-surface temperatures anomalies relative to the pre-industrial period

Left chart: A new approach for monitoring global temperature change since the 1850–1900 period is being used in line with the IPCC AR6 WGI report “Climate Change 2021: The Physical Science Basis” and the WMO statements on “The state of the global climate” from the Preliminary Statement for 2021 onwards. This approach results in a best estimate of 0.69°C with an uncertainty range (0.54 to 0.78 °C) to relate the standard WMO reference period 1981–2010 to 1850–1900. Datasets are normalized so that 1981–2010 average match with the ERA-5 average. The anomalies of each dataset are calculated relative to the average for 1981–2010 and then by adding the offset of 0.69° C to relate it to 1850–1900.

Right chart: For Europe there is no such “consensus” estimate for relating datasets to 1850–1900. Datasets are first normalised to 1981–2010 ERA-5 average. The anomaly values are relative to the 1850–1900 average. That average uses HadCRUT5 and Berkeley Earth for 1850–1879 and these two plus GISTEMP and NOAA GlobalTemp for 1880–1900. This is not what was done in the AR6 method to produce the consensus estimate for the global value, as it used only datasets that went back to 1850. 

Both charts: °C