At least 24 people died after a series of deadly storms across the southern and midwest US, with severe rains, flooding rivers and tornadoes triggering evacuation orders in several states.
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The record-breaking rain that triggered flash flooding in the southern and Midwest US in early April were intensified by climate change, a new study has concluded.
Heavy downpours affected the Central Mississippi river valley between April 2 and 6, with some areas receiving more than 400mm of rain, a record for the region. An unprecedented number of tornado warnings was also issued during the same period.
The extreme weather caused flash floods and triggered flash flood warnings across Mississippi, Arkansas, Missouri, Georgia, Illinois, Indiana, Kentucky, Tennessee, and Alabama, claiming at least 24 lives.
Scientists at World Weather Attribution, an international group looking at the possible influence of climate change on extreme weather events, said that climate change has made last month’s rainfall about 9% more intense. Their attribution study, published Thursday, also concluded that the unusual warmth of the sea in the Gulf of Mexico, which fed the storm moisture, was about 14 times more likely due to climate change.
A warmer atmosphere, heated by fossil fuel emissions, can hold more moisture, resulting in heavier downpours. For every 1C that Earth’s atmospheric temperature rises, the amount of water vapor in the atmosphere can increase by about 7%. Today, the planet is about 1.3C hotter than pre-industrial times.
The study looked at weather data and climate models to compare how rainfall events have changed between today’s climate and the cooler pre-industrial climate.
Atmospheric River
April’s downpoars were the result of a relatively common weather phenomenon in the West known as atmospheric river. Acting like nature’s superhighways, atmospheric rivers transport massive amounts of moisture, unleashing powerful snow or rainstorms wherever they flow.
But last month’s event was “exceptional”, Jay Cordeira, an atmospheric scientist with the Center for Western Weather and Water Extremes, told CNN. “It was as strong as they come.”
Atmospheric rivers are becoming increasingly frequent and carrying more moisture as a result of rising temperatures globally. With climate change knocking at our door and air and ocean temperatures rising, atmospheric rivers will only keep intensifying in strength, frequency, and length. Research suggests that total precipitation during atmospheric rivers in California will increase by up to 40% in a warming world.
Featured image: U.S. Department of Agriculture/Flickr.
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