Climate Change Helped Fuel Heavy Rains That Caused Hill Country Floods, Experts Say
Damp remnants of Tropical Storm Barry moved up from eastern Mexico as humid air also moved north from Mexico’s southwestern coast, stalling over Texas’ Hill Country. The warm air in both the low and high levels of the atmosphere is a recipe for intense rainfall, said John Nielsen-Gammon, the state’s appointed climatologist for more than 20 years.
He and his colleagues compiled a list of all the rainfall events in Texas that produced more than 20 inches of rain a few years ago. One common feature the climatologists found was when wind blew from south to north, or when moisture was brought northward from the tropics, he said. “That sets up the possibility of very heavy rainfall,” Nielsen-Gammon said. He concluded in a report last year that extreme rain in Texas could increase 10% by 2036.
Increased moisture from the tropics is driven by warming oceans.
The oceans absorb over 90% of excess heat in the atmosphere produced by greenhouse gas emissions, warming ocean temperatures down to depths of 2,000 meters. Tropical storms gain strength from heat and evaporate more quickly at higher temperatures, adding more water vapor to the atmosphere, Nielsen-Gammon said.
A study released Monday by ClimaMeter, a project funded by the European Union and the French National Center for Scientific Research, found that meteorological conditions leading up to Friday morning’s floods were warmer and 7% wetter than similar events of the past. Natural variability alone can’t explain the changes in rain associated with the exceptional weather, the report said, and points to human-caused climate change as one of the main drivers of the event.
ClimaMeter’s analysis shows the difference in surface temperature, precipitation and wind speed between the present climate from 1987 and earlier decades, from 1950 to 1986.
“Climate change loads the dice toward more frequent and more intense floods,” said Davide Faranda, one of the report’s authors who is research director of climate physics in the Laboratoire de Science du Climat et de l’Environnement, part of the French National Center for Scientific Research. “The flash flood that tore through Camp Mystic at night, when people were most vulnerable, shows the deadly cost of underestimating this shift.”
He added: “A 7% increase of rain is a lot, but doesn’t really make the tragedy. If you have a good alert system, if the population knows the risk related to climate change for this weather phenomena and can take them into account, not minimize them, then you can save lives, because it’s not double the amount of precipitation, it’s not three times. It’s something that we can handle if we are prepared.”
Other factors in the flooding death toll such as land use change, urban sprawl and warning system failures weren’t analyzed and may have further amplified the disaster, the report said.
“We are in a more extreme climate,” Faranda said. “And every year, year after year, we make it more extreme by burning more fossil fuels … These extremes now start to touch the limits of what is normal life on this planet, in terms of humans, in terms of infrastructure that we built with the old climate, in terms of resilience of the ecosystem.”
Initial estimates for the damage and economic loss of this disaster will reach beyond $18 billion, according to AccuWeather.
Arcelia Martin is an award-winning journalist at Inside Climate News.Inside Climate News’ staff writer Bob Berwyn contributed to this report. This story is published courtesy of the Texas Tribune.The Texas Tribune is a nonprofit, nonpartisan media organization that informs Texans — and engages with them — about public policy, politics, government and statewide issues. This story is published in partnership with Inside Climate News, a nonprofit, independent news organization that covers climate, energy and the environment. Sign up for the ICN newsletter here.