Northern and Southern Hemisphere Warming

by A. May, Mar 18, 2022 in WUWT


As shown in Figure 1, the Hadley Climatic Research Unit HadCRUT5 temperature dataset suggests the Northern Hemisphere warmed 0.74°C (1.3° F) more than the Southern Hemisphere from 1979 through 2021. The UAH satellite temperature lower troposphere record is directionally similar but the difference between the hemispheres is much less, as shown in Figure 2. Both figures have identical vertical scales of 1.4°C. The UAH global satellite warming difference, from 1979 to 2021, between the hemispheres is about 0.2°C (0.4° F), less by more than a factor of 3.

Conclusions

The UAH and HadCRUT5 records both show the Northern Hemisphere warming more rapidly than the Southern, but the amount of extra warming in the HadCRUT5 record is anomalous. While the Southern Hemisphere satellite and surface rates are similar, the Northern Hemisphere rates are very different.

The global UAH lower troposphere and HadSST4 warming rates are both 0.14°C/decade from 1979 to 2020, the same to two decimals, as shown in my previous post. The oceans cover 70% of Earth’s surface and the HadSST4 dataset is used in combination with the CRUTEM5 land-surface temperature record to produce the curves in Figure 1. Given this, the large difference in Northern Hemisphere warming rates between Figures 1 and 2 is very hard to explain. Frankly, it suggests there is a problem with CRUTEM5. Figure 3 suggests the problem is getting worse in recent years, not better. This topic is discussed in more detail in my latest book: The Great Climate Change Debate: Karoly v Happer.