State Climatologist Blames Harvey Intensity on Global Warming

If you asked me five years ago, a conference hosted by the energy industry is exactly where I’d go to hear the findings of climate change skeptics.

The Gulf Coast Power Association is an energy group with a diverse list of members from Shell to SolarCity. At their fall conference in Austin earlier this month, Texas A&M climatologist John Neilsen-Gammon presented on Hurricane Harvey’s record-breaking rainfall.

His big takeaway: It’s time to blame climate change.   

According to Neilsen-Gammon’s presentation, warmer temperatures fueled Harvey’s extreme rainfall. As to whether it impacted the storm’s existence, he writes on the slide, “doubtful”. On shaping the storm’s path, he writes “unknown”. As for the storm’s Category 5 intensity, a shrug: “possible influence”.

But right underneath that he asks, “Precipitation?” And this time, the answer is definitive: “Enhancement”.

Over the course of five days, Hurricane Harvey dumped an average of 33 inches of rain per day over 10,000 square miles. In terms of average precipitation, the next closest storm of comparable size and length was in Texas 1899, when rainfall averaged around 21 inches daily. Overall, Hurricane Harvey broke most of the rainfall records by duration and area in the central and eastern U.S.

Neilsen-Gammon’s graph predicts that roughly three inches of Harvey’s downpour can be attributed to climate change. And though that’s just ten percent of the storm’s total daily rainfall, it’s significant for a low-lying region like Houston with clay soils that drain poorly. 

Furthermore, the effect of rainfall on flood damage isn’t linear. In a major storm, a difference of just a couple inches of rain over the course of a day can lead to dam spills, sewage overflows and levee breaks, if the storm is wide enough and the watershed is large. Flood damage from Harvey is estimated at $150 billion, about the same cost as Hurricane Katrina.

Ironically, as the Trump administration begins dismantling the Clean Power Plan, energy companies are finally publicly acknowledging the facts of climate science. Given Neilsen-Gammon’s analysis, there are no more excuses to be made.  Energy companies need to shift now to zero-carbon renewables, before Harvey’s record-breaking rains become the devastating norm.