Jan 13, 2017

Nature Not NOAA Ended the Slowdown in Temperatures

Zeke Hausfather
Berkeley Earth

each group has a different methodology, much of the underlying data is the same. NOAA, the UK’s Hadley Centre, and independent researchers Cowtan and Way (C&W) use effectively the same land data (the Global Historical Climatological Network, or GHCN for short). NASA also uses GHCN data, but adds additional stations in the U.S. and in the Arctic and Antarctic. Berkeley uses a much larger set of stations (about 36,000 stations, compared to around 7,000 for the other records), though NOAA will be switching to a similarly large database of stations soon. Berkeley, Hadley, and C&W all use a sea surface temperature series called HadSST3 produced by the Hadley Centre. NOAA and NASA use a sea surface temperature series called ERSST (version 4) produced by NOAA.

Automated adjustments to land data to remove detected problems like station moves or instrument changes are used by NOAA, NASA, and Berkeley Earth; Hadley and C&W do relatively little adjustments to land data outside of quality control. NOAA and Hadley only calculate temperatures in areas with nearby stations, while NASA, Berkeley, and C&W fill in areas without stations based on statistical techniques using the nearest available stations.

No matter which groups’ record you use, you end up with a pretty similar global temperature record. Figure 2, below, shows the trend in temperatures for three periods: 1950-present, 1970-present, and the nominal “slowdown” period of 1998-present. It shows that while the 1998-present period is warming a tad slower than the 1970-present period on average, the uncertainties are large and the warming rate over the post-1998 period is pretty much the same as the longer 1950-present period.