Uncertainty estimates in regional and global observed temperature changes: A new data set from 1850

TLDR

The historical surface temperature data set HadCRUT provides a record of surface temperature trends and variability since 1850. A comprehensive set of uncertainty estimates has been derived to accompany the data, including measurement and sampling error, temperature bias effects, and the impact of limited observational coverage on large‑scale averages. HadCRUT3, an updated dataset incorporating improved sea surface and station records, shows that since the mid‑twentieth century global and hemispheric mean temperature increases far exceed their uncertainties, and even in earlier periods the twentieth‑century rise remains significantly larger than the associated uncertainties.

Abstract

The historical surface temperature data set HadCRUT provides a record of surface temperature trends and variability since 1850. A new version of this data set, HadCRUT3, has been produced, benefiting from recent improvements to the sea surface temperature data set which forms its marine component, and from improvements to the station records which provide the land data. A comprehensive set of uncertainty estimates has been derived to accompany the data: Estimates of measurement and sampling error, temperature bias effects, and the effect of limited observational coverage on large‐scale averages have all been made. Since the mid twentieth century the uncertainties in global and hemispheric mean temperatures are small, and the temperature increase greatly exceeds its uncertainty. In earlier periods the uncertainties are larger, but the temperature increase over the twentieth century is still significantly larger than its uncertainty.