Nature paper: Global droughts unchanged in 60 years

By Jo Nova

How many images have we seen of drought-stricken cracked land, or been told this is the future? How many headlines have suggested that global warming causes droughts?

Since the end of World War II humans have produced some 85% of all their CO2 emissions, but here is a new study showing that for all those emissions, and for all that warming, droughts back then were just as bad globally as they are today.  Essentially, researchers thought that the Palmer Drought Severity Index (PDSI) was the way to measure global drought levels, and they thought that warming would increase global drought conditions. But the PDSI considers only temperature, not humidity, sunlight and wind. This paper shows that when these factors are included, worldwide drought is about the same now as it was in 1950.  Researchers are finally accounting for the fact that a warmer world usually means more evaporation (especially from the ocean) and thus more rain. It’s good to see that someone has crunched those complex numbers on a global scale. Credit to Sheffield, Wood & Roderick.  To Read More….