New Paper By Zhou et al Surprises! …Heavy Precipitation Under Global Warming Likely “Overestimated”

A warmer world with more precipitation? That is plausible as warmer air means a higher moisture and water vapor carrying capacity. The risk of droughts thus would be reduced. However, do higher temperatures lead to drastic increase in extreme rainfalls? Some scientists prematurely made up their minds and sold the media their personal opinion of settled science. Here they hide the fact that this is in fact heatedly debated within the science community.

Very recently a new paper appeared in the Geophysical Research Letters, authored by Yu Zhou et al of the Max Planck Institute for Physics of Complex Systems. The scientists found errors in the statistical processing of extreme precipitation data. Once corrected, the data show that extreme precipitation have even declined over the past 15 years. When accounting for the past 25 years, they found a much weaker relationship between extreme precipitation and temperature than that found by other groups.

Zhou et al conclude that the danger from extreme precipitation events as a consequence of global warming was strongly overestimated and that it must be corrected downwards.

In the future extreme rain may even become less.

What follows is the paper’s abstract:

On the detection of precipitation dependence on temperature
Employing their newly proposed interannual difference method (IADM), Liu et al. (2009) and Shiu et al. (2012) reported a shocking increase of around 100% K⁻¹ in heavy precipitation with warming global temperature in 1979–2007. Such increase is alarming and prompts us to probe into the IADM. In this study, both analytical derivations and numerical analyses demonstrate that IADM provides no additional information to that of the conventional linear regression, and also, it may give a false indication of dependence. For clarity and simplicity, we therefore recommend linear regression analysis over the IADM for the detection of dependence. We also find that heavy precipitation decreased during the global warming hiatus, and the precipitation dependence on temperature drops by almost 50% when the study period is extended to 1979–2014 and it may keep dropping in the near future. The risk of having heavy precipitation under warming global temperature may have been overestimated.”