Global warming is leading to more extreme droughts and floods, NASA satellites show
Twenty years of global satellite data from NASA shows just how much the magnitude, duration and severity of extreme droughts and floods have increased alongside warming global temperatures, a new study shows.
The study examined the timing of such events and where they occur around the world, said study co-author Matthew Rodell, a scientist at NASA’s Goddard Space Flight Center.
The study, published in the journal Nature Water, found a strong correlation between extreme wet and dry events and temperature increases.
More extreme events — more frequent, larger, and more severe — have occurred in the later years since 2015, which included the warmest Top 10 on record, Rodell said.
The work adds to a growing body of evidence suggesting continued warming could cause more frequent, widespread, and severe droughts and floods.
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Weather events change
When you have warmer temperatures, you see those more intense events happening and happening more frequently, Rodell said. It is “very likely that as the world continues to warm, we will experience more frequent and severe droughts and[periods of increased precipitation].”
Warmer air causes more evaporation during droughts and increases the amount of water available for thunderstorms and other precipitation during wet events.
A 2021 USA TODAY investigation showed that extreme rains have increased in the eastern half of the United States, but droughts have become more frequent and intense.
Investigation: How a summer of extreme weather reveals a startling change in the way rain falls in America.
Years of study had predicted this might be the case, but like the research, most academic studies use precipitation data.
Rodell and Bailing Li, University of Maryland employees at the Space Flight Center, used information from NASA satellites. Rodell said the more accurate data helps account for underestimates that occur with extreme precipitation data and uncertainties in rain and snow measurements at higher elevations.
What have the scientists done?
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Observed: Changes in land-based water storage, including groundwater, soil moisture, snow and ice, and surface water around the world, as measured by remote-sensing satellites.
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Found: 505 rain events and 551 extreme dry events from 2002 to 2021 with an average duration of 5 to 6 months.
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Analyzed: Monthly temperature records and monthly total intensity of all wet and dry events and comparison of these.
What did you find?
One of the most important findings: A decrease in the frequency of rain events in the US and an increase in dry events, such as the drought series in the Southwest since 2012.
Also:
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A “strongly correlated” link between global mean temperature and the intensity of extreme wet and dry events – combining magnitude, duration and severity.
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A stronger association with temperature than with El Nino or other circulation patterns.
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A shift from wetter to drier events in southeastern Brazil and within a “wide swath from southern Europe through the Middle East and Arabian Peninsula to southwestern China and Bangladesh.”
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More drought events in sub-Saharan Africa and west-central South America in the first half of the 20-year period and more rain events in the second half.
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A major flood event that covered most of Central Africa as of 2019 and was still ongoing in late 2021 was three times the size of the next largest wet or dry event in the entire 20-year span.
How precipitation is changing in the US: See how it changed your community
Satellite data versus precipitation data
“People intuitively recognize that extreme events are more common, but it was hard to say for sure,” Rodell said. “The satellite data gives us a new perspective, which gives us a certain level of confidence that it’s already happening.”
“We’re not always good at measuring extreme rainfall,” he said. And measurements of rain and snow can’t account for evaporation and runoff, and don’t see the “big picture” of the total amount of water gained or lost.
Rodell and Li used satellites known as the GRACE satellites for the Gravity Recovery and Climate Experiment. The satellites measure the reflected light and monitor each other’s orbits, accounting for the force of gravity affecting all the data collected, and measuring their orbits “incredibly accurately.”
Similar to how the US Drought Monitor provides regular monitoring of drought conditions in the country, “the approach presented by Rodell and Li may allow for regular monitoring of extreme wet and dry events worldwide,” Melissa Rohde wrote in an article also published in Nature Water March.
“Detecting drought and flood events before they intensify can help water managers respond appropriately to reduce negative impacts,” she said. The Goddard scientists’ approach “can help convey the urgency of dealing with climate change.”
Dig deeper:
Recent videos of droughts around the world:
Dinah Voyle’s Pulver covers climate and environmental issues for USA TODAY. She can be reached at [email protected] or at @dinahvp on Twitter.
This article originally appeared on USA TODAY: Global Warming Leads to More Extreme Droughts, Floods, NASA Data Shows
