The severe drought that has hit the southwestern United States since 2000 is the worst recorded in 1,200 years. B – including New Mexico, Arizona, Nevada, California and Utah – was caused by a lack of precipitation and high temperatures. A previous study examining the drought until 2018 determined that it was the second most severe since the year 800, when only a prolonged drought in the late 16th century was longer.
But the new study, published in the journal Nature Climate Change, found that the past three years, and especially last year’s drought conditions, exacerbated the crisis and made the current mega-drought the most difficult in 1,200 years. According to scientists, the drought is also expected to continue in the current year and thus it will be equal in length to an event of the 16th century.
Scientists have used tree trunk rings from three sites in the west of the continent to restore soil moisture and snowwater since 800, and combined this with climatic models to examine the effects of greenhouse gas emissions. Their conclusion was that the 22 years of the 21st century were drier than the second half of the 20th century, with a 8.3% decrease in precipitation and warming of close to one. Another finding was that climate change caused by human activity had a 42% contribution to soil anomaly throughout the current drought, with 19% measured only last year.
“Without climate change, it would not even be close to being one of the historical mega-droughts,” said study leader Prof. A. Williams Park of the Department of Geography at the University of California, Los Angeles, who also led the previous study in 2018. “It is very likely that this drought will not end in a single wet year,” added Williams, who noted that it takes several years of above-average amounts of rain and snow to overcome the historic crisis.
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