A combined estimate of global temperature

Recently several global temperature series have been updated using new data sets, new methods, and for a statistician most importantly, assessments of their uncertainties. This enables us to produce a timely estimate of the annual global mean temperature with a combined estimate of uncertainty. We describe the hierarchical model we propose, and a Bayesian scheme for fitting the model. In addition, we test the sensitivity to the results to each of the series, identifying groups of data products that act similar to one another. Using the combined estimate of the global temperature series, we estimate that the probability that 2020 was the warmest year on record is 0.41.