Did Climate Change Cause Hurricane Harvey? Plus What to Expect in the Storm’s Aftermath cover

Did Climate Change Cause Hurricane Harvey? Plus What to Expect in the Storm’s Aftermath


The astonishing ferocity of Hurricane Harvey may mark the moment when the discussion linking extreme weather with climate change got seriously widespread.
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Did Climate Change Cause Hurricane Harvey? Plus What to Expect in the Storm’s Aftermath

The astonishing ferocity of Hurricane Harvey may mark the moment when the discussion linking extreme weather with climate change got seriously widespread. At The Intercept, Naomi Klein says there hasn’t been much talk about climate change and Harvey, but I think she’s wrong.

It probably helps that Harvey is the most extreme of extreme weather events, or at least is on track to produce the most stormborne havoc ever in the US. Shane Hubbard, of the University of Wisconsin’s Space Science and Engineering Center, has declared Harvey to be a thousand-year flood event, according to Jason Samenow of the Capital Weather Gang. (If you think that means a storm that will occur only once in a thousand years, think again. See Maggie Koerth-Baker’s explanation of the math, discussed below.)

Searching for survivors in a destroyed mobile home after hurricane Harvey near Rockport, Texas, Aug. 27. Credit: Glenn Fawcett, U.S. Customs and Border Protection

Some of that post-Harvey havoc is due, of course, not to climate change, but to willful and woeful lack of preparation plus our crazed penchant for building in ridiculous places. But I’ve been tracking this topic informally for years.

This time, without even trying hard, I’ve encountered dozens of posts laying out the case that Harvey would have been a lesser storm had the Earth not been warming. CarbonBrief has summarized some of the early media reaction. So did Tim Profeta at National Geographic

Expert judgment comes with appropriate cautions, of course. At The Conversation, climatologist Andrew King says it’s indubitable that tropical cyclones like Harvey have increased in the North Atlantic. “It is likely that climate change has contributed to this trend, although there is low statistical confidence associated with this statement. What that means is that this observed increase in hurricane frequency is more likely than not linked with climate change, but the increase may also be linked to decadal variability.”

Storm surges are related to warming because warming has caused sea levels to rise. But storm surges have not been much of a Harvey feature, King says; the problem was instead heavy rain. Warming does increase rainfall because warmer air holds more water, 7% more for every degree F. of temperature increase.

And, as I observed above, we humans make it worse. At Quark Soup, David Appell notes that the land in parts of Harris County (Houston’s home) has subsided between 10 and 12 feet since the 1920s. That’s because people have been drawing so much water out of the aquifers.

Some experts are more uncertain than others. As Ronald Bailey points out at Hit&Run, last year’s National Academy of Sciences’s report, Attribution of Extreme Weather Events in the Context of Climate Change, notes that assessment of changes in probability or magnitude of storms depends on historical records, especially how long they’ve been kept.

Bailey says, “Climate computer models suggest that hurricanes will increase in frequency and intensity should the planet warm over the course of this century. The NAS report, however, assigns “lower confidence” to making attributions about how climate change may be affecting hurricanes.” He also points out that studies in the US and Europe have fairly consistently found no historical increase in flooding.

The controversial environmental scientist Roger Pielke Jr. argues that weather-related financial losses have not increased significantly through 2013.

Hurricane Harvey, August 27, in Roman Forest, TX. Credit: Jill Carlson.

However, Bailey notes, “Last month, Pielke observed, “The world has had a run of good luck when it comes to weather disasters. That will inevitably come to an end.”

And maybe Harvey is The End? Many–including Our Dear Leader–are saying the storm will be the US’s most expensive natural disaster ever.

The Health & Safety Aftermath of Hurricane Harvey

Texas is home to an enormous chemical industry, with the emphasis on petrochemicals. Plant shutdowns as a result of Harvey have released huge amounts of toxic pollutants, recounts Emily Atkins at Grist. Her even more sobering conclusion: “The real problem lies in the sheer number of facilities having to shut down or decrease operations at the exact same time — meaning they’ll also all eventually have to start back up. And emissions-wise, starting back up is just as bad as shutting down.”

And as we all learned in high school chem lab, sometimes by accident, chemicals can explode. Explosions at an organic peroxide plant about 25 miles from Houston have been predicted for days, and they finally happened Thursday.

The component chemicals explode if not kept cool. Brian Resnick is keeping an eye on things there at Vox.

Harvey’s consequences for health stretch far into the future. But not all of them.

Incidental Economists Aaron Carroll and Austin Frakt note at The Upshot that researchers have shown “that wounds, poisonings and infections of the gut and skin increase soon after storms. Gastrointestinal infections increase more frequently after floods. Diabetes-related complications increase after both.”

Post-hurricane Harvey, on August 27, a raft of fire ants in Pearland, Texas. Credit: Brant Kelly

Health problems particularly plague people with chronic conditions. Distribution of drugs and other medical supplies gets disrupted. Harvey shut down dozens of dialysis centers, even though kidney patients may need dialysis several times a week.

Long-term physical and mental-health problems get less attention as media and public interest in a severe storm fades. But the death rate goes up for months, including suicide.

One study detected symptoms of mental trauma, PTSD, and depression two years after serious flooding. Effects may be especially severe and long-lasting in infants and children. Natural disasters can even have a negative effect on pregnancies that don’t begin until after the event, Carroll and Frakt say.

The Policy Aftermath of a 100/500/1000-Year Flood

If you’ve been thinking that “100-year flood” (or the 1000-year flood described at the beginning of this post) means a flood so rare it will occur only once a century (or a millennium), you’re being misled.

As Maggie Koerth-Baker explains a 100-year flood at FiveThirtyEight, “Instead, it refers to a flood that has a 1 percent chance of happening in any given year. Over the course of a 30-year mortgage, a house in a 100-year floodplain has a 26 percent chance of being inundated at least once.” (So cheer up. That means, in the case of a 1000-year flood (like Harvey?), there’s just a 0.1 percent chance of such an event in any given year.)

Furthermore, she says, the term obscures statistical problems in how flood risks are assessed. Her post explains them. Not least, flood plain designations are often based on less than 20 years of data.

It’s probably time to find a different methodology, but easier said than done. Flood experts do not agree on the best ways to do that. And even if there was a consensus, inertia and money would be likely to block action.

And then there’s the human disinclination to face up to future risks even when people have had years of advance warning, as certainly was the case in Houston. Willful blindness of that kind, Laura Bliss points out at CityLab, “is not a uniquely Texan brand of magical thinking.”

Satellite image of Hurricane Harvey near peak intensity on August 25 shortly before landfall in Texas. Credit: US Navy.