Recent analysis by the World Weather Attribution group highlights that human-induced climate change exacerbated the severe rainfall experienced in Arkansas, Kentucky, Tennessee, and surrounding areas in early April. This intensification has also increased the likelihood of such storms occurring.
Between April 3-6, a cluster of storms struck the central Mississippi Valley, bringing tornadoes, fierce winds, and intense rainfall, resulting in at least 24 casualties. The deluge caused significant flooding, impacting homes, roads, and vehicles, with catastrophic floods accounting for approximately 15 of the deaths.
The investigation conducted by WWA indicates a 9% rise in rainfall intensity due to climate change, alongside a 40% increase in their likelihood compared to their frequency in the pre-industrial climate era.
Some of the moisture that fueled the storms came from the Gulf of Mexico, where water temperatures were abnormally warm by 1.2°C (2.2°F) compared to pre-industrial temperatures. That warming was made 14 times more likely due to climate change, according to the researchers from universities and meteorological agencies in the United States and Europe.
Rapid analyses from the WWA use peer-reviewed methods to study an extreme weather event and distill it down to the factors that caused it. This approach lets scientists analyze which contributing factors had the biggest influence and how the event could have played out in a world without climate change.
The analysis found a rainfall event of April’s intensity could occur in the central Mississippi Valley region about once every 100 years. Even heavier downpours are expected to hit the region in the future unless the world rapidly slashes emissions of polluting gases such as carbon dioxide and methane that causes temperatures to rise, the study said.
“That one in 100 years … is likely to go down to once every few decades,” said Ben Clarke, a researcher at the Centre for Environmental Policy at Imperial College London and the study’s lead author. “If we continue to burn fossil fuels, events like this will not only continue to occur, but they’ll keep getting more dangerous.”
Heavier and more persistent rainfall is expected with climate change because the atmosphere holds more moisture as it warms. Warming ocean temperatures result in higher evaporation rates, which means more moisture is available to fuel storms.
Forecast information and weather alerts from the National Weather Service communicated the risks of the April heavy rain days in advance, which the WWA says likely reduced the death toll. But workforce and budget cuts made by the Trump administration have left nearly half of NWS offices with 20% vacancy rates or higher, raising concerns for public safety during future extreme weather events and the upcoming Atlantic hurricane season that officially begins June 1.
“If we start cutting back on these offices or reducing the staff … the unfortunate result is going to be more death. We’re going to have more people dying because the warnings are not going to get out, the warnings are not going to be as fine-tuned as they are today,” said Randall Cerveny, a climate professor at Arizona State University who was not involved in the study.
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