This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: As climate change continues to affect the U.S., many regions throughout the country, especially the West, are experiencing more drought. But over the past century, the Northeast has experienced something different—less frequent and less intense droughts because of increased precipitation, according to a new Dartmouth study.
The findings are published in the Journal of Hydrometeorology. As Earth gets warmer, there is more energy available to evaporate water from plants and soils. If there isn't more rainfall to cover that water loss, more drought will occur.
"In the Northeast, we have warming temperatures, which means we lose more water from the surface, but we have also had increasing precipitation," says lead author Jonathan Winter, an associate professor of geography and director of the Dartmouth Applied Hydroclimatology Group, whose work has explored extreme precipitation changes in the region. "It's a tug-of-war between how fast precipitation is increasing and how fast evapotranspiration—the loss of water from plants and soils—is increasing." The research team assessed changes in monthly drought from 1901 to 2022 across the Northeast—Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Washington, D.C., and West Virginia—using temperature and precipitation station data from the National Oceanic and Atmospheric Administration. To examine changes in drought across the region, the team analyzed the intensity, frequency, variance and duration of drought.
Using temperature, precipitation, radiation and soil data, they calculated the Palmer Drought Severity Index—a metric used to measure drought. The researchers compared their results with the U.S. Drought Monitor—a weekly map identifying areas in drought—which is used to determine crop insurance payouts.
They also compared their findings with changes in soil moisture. Given that soil moisture measurements across the region are limited, the team used modeled soil moisture, which blends a climate model with observational data. The findings show that across all months, drought was 59% less frequent and 19% less intense from 1984 to 2022 compared with 1901 to 1983.
Results were similar in the warm season (June–November), when drought has the largest impacts; warm-season drought frequency and intensity decreased by 56% and 16%, respectively. The results also demonstrate that as of 1984, the Northeast was statistically wetter relative to the earlier period. Swings between monthly wet and dry events have not changed, demonstrating that the Northeast has not experienced more "weather whiplash," or alternating floods and droughts.
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