Texas’ Record Floods Are the New Normal
Storm after storm drenched Texas in May—torrential downpours strong enough to cover the entire state in the equivalent of eight inches of water. The nonstop rain caused $45 million in damage in Houston alone, but it also brought short-lived relief from a record-setting five-year drought.
While scientists discourage linking specific weather events to climate, a study published Wednesday in the journal Geophysical Research Letters found that Texas and Oklahoma can expect more rainfall in El Niño years like this one, thanks to, yes, climate change.
The research, led by Utah State climate scientist Simon Wang, looked at the record flooding that hit the southern Great Plains region of Texas and Oklahoma in May and found that global warming played a role in intensifying those floods.
Exactly how much more intense, Wang couldn’t say.
Putting “a quantitative assessment, like a percentage amount, of greenhouse gas impact on an event is difficult,” Wang said in an email. “In our case, because climate models only could simulate similar events, but not repeating the exact event, we could only indicate that without greenhouse gases, the amount of precipitation would not be so large.”
Still, the models determined that if greenhouse gas levels were at preindustrial levels, flood severity during El Niño years would be reduced by 50 percent.
If carbon emissions from burning fossil fuels continue unabated, the waters in the tropical Pacific Ocean will keep warming. By the end of the century, when an El Niño weather pattern hits, it could double the frequency and intensity of rainfall in the region, the study found.
“Our study’s intention was not so much on seeing if global warming would enhance extreme events like this one in Texas. Rather, we hope to provide a tool (or guideline) to help predict future events as early as possible, so that the society can mitigate and plan better,” Wang said.
He noted that the study analyzed non–El Niño years too and found the opposite was true for the region. In La Niña years, when surface ocean temperatures are cooler than normal in the equatorial Pacific, the southern Great Plains should expect longer, drier droughts—similar to what the Texas has experienced over the last five years.
Even with a “Godzilla El Niño” on the horizon, Texas state climatologist John Nielsen-Gammon says drought remains a concern.
“During the two strongest El Niños, rainfall amounts were only about 5 percent greater than normal” in Texas, Nielsen-Gammon said in a statement. “It’s possible that there might be a ‘sweet spot’ for El Niños that produces the biggest effect on wintertime rainfall in Texas, and these strong events tend to overshoot that sweet spot. But with only two such events to look back on, it’s difficult to know whether all super-strong El Niños will be ‘Goliaths’—big, but not that effective.”