Droughts in the Western U.S. have risen to an "unprecedented" level since the 16th century, a new study has revealed.
"Hot drought" refers to concurrent drought conditions that are stretching across the country, largely because of climate change. The study from multi-institutional researchers, published in the journal Science, found that these severe conditions have been increasing in not just severity but how often they have occurred over the past 100 years.
To get these findings, lead author Karen King and colleagues combined summer temperatures in the U.S. from 1553 to 2020 by analyzing tree rings, which show temperature changes through soil moisture. They discovered that the past 20 years in the Western U.S. have been the hottest in over five centuries.
"If anthropogenic warming continues according to model projections, we might assume that anthropogenic drying has only just begun," King, an assistant professor of physical geography at the University of Tennessee, told Newsweek. "Furthermore, we might expect the frequency of compound hot and dry conditions—hot drought—to increase over the course of this century."
A stock photo pictures ground cracked with drought. New research shows that the past 20 years in the Western U.S., which has been severely afflicted by drought, have been the hottest in over five centuries.A stock photo pictures ground cracked with drought. New research shows that the past 20 years in the Western U.S., which has been severely afflicted by drought, have been the hottest in over five centuries.piyaset/GettyThese hot temperatures have increased the soil moisture, which in turn has contributed to the severity and frequency of drought. The researchers have linked the notable increase in drought to human activities.
"Individual climatic events can have serious effects on agriculture, infrastructure, and ecosystems, but compounding hazards can result in cascading and intensified consequences for these systems," the authors write in the study.
They went on: "The combination of anomalous heat with rainfall deficits have already led to droughts that are substantially more intense because of high temperatures and elevated vapor pressure deficits and have thus been called hot droughts."
The research is easy to believe, considering the severe effects of drought we are already seeing in the Western U.S. The region is facing a severe water crisis as megadrought continues to plague the area.
The Colorado River Basin is seeing a concerning drop in water levels as drought causes a lack of seasonal precipitation. Important Colorado River reservoirs like Lake Mead are showing how dire the situation is. In the summer of 2022, the reservoir reached its lowest level ever recorded. Since then, the water levels have remained at only around 30 percent capacity.
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"The increasing prevalence of hot drought over the 20th and 21st centuries has important implications for future regional climate change adaptation strategies and for water resource management, particularly in the most historically drought-prone regions," the study said.
"This study aims to evaluate the relationship between summer average maximum temperatures and summer soil moisture over the last 500 years," King said. "Our main research questions are, [firstly] how might we characterize or quantify the relationship between summer maximum temperature and summer soil moisture during this modern period of megadrought conditions for much of western North America compared to during past megadrought periods over the last 500 years? [And secondly,] has the frequency of compound hot and dry summers increased over the 20th-21st centuries compared to the past ca. 500 years?"
Experts are already aware that drought is wreaking havoc across the globe. In December 2023, the United Nations reported that drought is starting to become an unprecedented planetary-scale emergency.
At the time of this research, Daniel Tsegai, program officer at the global policy advocacy and regional cooperation unit at the United Nations Convention to Combat Desertification, told Newsweek that drought is hitting many areas of the U.S.
"Our research team is currently working to expand the Western North American Temperatures Atlas to provide complete spatiotemporal coverage of past summer temperature estimates for the North American continent, spanning at least the last 500 years," King said. "Completion of the full North American Temperature Atlas will allow for broader spatial comparisons of compound climate extremes though time."
Update 01/25/24, 5:59 a.m. ET: This article was updated with direct quotes from Karen King.
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