Torrential rains and “catastrophic” flash flooding that hit central Texas over the holiday weekend have left more than 100 people dead, including dozens of children.
Forecasts and alerts from the National Weather Service projected heavy rainfall, but downpours in the darkness of night and quickly rising river levels may have led to many people not being able to evacuate and reach safe areas.
Although it is impossible to say that specific weather events are due to — or caused by — climate change, it is likely that extreme rainfall and flooding have been amplified due to human-induced climate change, climate scientists told ABC News.
This means that climate change is likely to make extreme weather events, like those experienced in Texas, occur more intensely and more frequently.
“There’s abundant evidence that this is one of the specific types of extreme weather events that have already increased considerably around the world as a result of the warming that’s already occurred,” Daniel Swain, a climate scientist at the California Institute for Water Resources within University of California Agriculture and Natural Resources, told ABC News.
“By that, I specifically mean highly extreme rain events that are either at the upper end or beyond what we’ve seen historically,” he continued. “There is strong evidence that those events will, and indeed already have, increased due to warming.”
Swain said forecasts from the NWS were accurate, but even the best projections cannot predict the specific intensity or the exact location where the floods would be worst days or weeks in advance.
Andrew Dessler, a professor of atmospheric science and director of the Texas Center for Extreme Weather at Texas A&M University, said one of the oldest predictions of climate science is that intense rain events are going to become more intense.
“The primary reason is that warmer air simply holds more water,” he said. “And so, as this warm, moist air flows into the storm and starts to ascend in thunderstorms, all of the water gets wrung out.”
The Gulf, which borders Texas, has become significantly warmer in recent years due to climate change, Swain explained.
This results in a very warm body of water that produces a lot of evaporation, releasing more tropical moisture into the air than seen historically.
“Depending on where you are, that moist air is forced to rise as it ascends the topography,” Swain said. “It therefore cools and condenses into clouds when the atmosphere is conducive for thunderstorms.
Jennifer Marlon, a senior research scientist at the Yale School of the Environment, said flash floods have always occurred, but global warming due to fossil fuel use is making them worse.
“That’s likely what happened in Texas,” she told ABC News. “Scientists have known that burning fossil fuels heats the planet for over 100 years. Using gas-powered cars and making electricity by burning methane adds massive amounts of heat-trapping carbon dioxide to the air. That heat fuels more violent weather because warmer air holds more water.”