Visualisations of the full timeseries of global and hemispheric temperature anomalies, using 12-month running means.

The temperature dataset is our HadCRUT4 data.

12-month running mean values

These graphs show the 12-month running-mean temperature anomalies (blue line). Their estimated uncertainties (pale blue shading) are assumed to be equal to the uncertainties of annual means.

Using 12-month running means avoids the abritrary division into calendar years for annual averages, and so it can better capture short-lived anomalies (e.g. those associated with ENSO events) that do not necessarily align with calendar years. It also allows the most recent data to be included (indicated by a red circle and label) and compared with earlier values on a like-for-like basis (avoiding comparing a partially-complete current year with complete previous years).

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References

• Morice, C.P., Kennedy, J.J., Rayner, N.A. and Jones, P.D., 2012: Quantifying uncertainties in global and regional temperature change using an ensemble of observational estimates: the HadCRUT4 dataset. Journal of Geophysical Research, 117, D08101, doi:10.1029/2011JD017187