Human-caused warming intensified Hurricane Harvey’s rains
New research shows human-induced climate change increased the amount and intensity of Hurricane Harvey’s extreme rainfall. The new findings are published in Environmental Research Letters and were presented in a press conference on 13 December at the 2017 American Geophysical Union Fall meeting.
During August 2017, Hurricane Harvey stalled over Texas and
caused particularly extreme rainfall over Houston and the surrounding area. This resulted in extensive flooding with over 80 fatalities and significant economic costs.
The study by World Weather Attribution researchers  examined the observed rainfall record in the Gulf coast region since 1880, showing that the intensity of such rainfall has increased significantly. Climate models confirmed the trend is mainly due to anthropogenic climate change.
Overall, the study says, the chances of a rainfall event as intense as Harvey have roughly tripled (between 1.5 and 5 times more likely) since the 1900s, and the intensity of such events has increased by between 8% and 19%.
Karin van der Wiel, a postdoctoral researcher at the Royal Netherlands Meteorological Institute in the Netherlands presented the research at the AGU press conference. Climateprediction.net’s Dr Friederike Otto, Karsten Haustein and Sihan Li are co-authors, along with researchers from Delft University of Technology, Rice University, Red Cross Red Crescent Climate Centre, Princeton University and Climate Central.
The analysis makes clear that extreme rainfall events along the Gulf Coast are on the rise. Information regarding the increasing risk of extreme rainfall events in general could be critical to the discussion about future improvements to Houston’s flood protection system.
Dr Friederike Otto says, “We’re now finding that for many kinds of extreme weather event, especially heatwaves and extreme rainfall, we can be quite confident about the effect of climate change. Whether policymakers are looking at local issues such as flood protection or involved in the global climate change negotiations, the more information they have about climate change impacts now and in the future, the better decisions they’re able to make”.
 Attribution of Extreme Rainfall from Hurricane Harvey, August 2017
Geert Jan van Oldenborgh1, Karin van der Wiel, Antonia Sebastian, Roop Singh, Julie Arrighi, Friederike Otto, Karsten Haustein, Sihan Li, Gabriel Vecchi and Heidi Cullen