West LA Times

A recent study by scientists from UCLA and the National Oceanic and Atmospheric Administration (NOAA) has revealed that higher temperatures due to climate change intensified a drought in the American West between 2020 and 2022. The research indicates that evaporation was responsible for 61% of the drought's severity, while reduced precipitation accounted for 39%.

Rong Fu, a UCLA professor of atmospheric and oceanic sciences, noted, "Research has already shown that warmer temperatures contribute to drought, but this is, to our knowledge, the first study that actually shows that moisture loss due to demand is greater than the moisture loss due to lack of rainfall."

Historically, Western U.S. droughts have been attributed mainly to insufficient rainfall. However, climate change from fossil fuel emissions has increased average temperatures, complicating this understanding. Veva Deheza from NOAA stated, "This study further confirms we’ve entered a new paradigm where rising temperatures are leading to intense droughts, with precipitation as a secondary factor."

The researchers analyzed data over 70 years to differentiate between natural weather pattern-induced droughts and those influenced by human-caused climate change. They found that since 2000, climate change has driven 80% of the increase in evaporative demand.

Compared with data from 1948-1999, the average drought area increased by 17% from 2000-2022 across the American West due to higher evaporative demand. In regions prone to historical and emerging droughts since 2000, high evaporative demand alone could cause drought without a precipitation deficit.

Fu highlighted how during the recent drought period, "moisture demand really spiked," exacerbating its severity from moderate to exceptional on the U.S. Drought Monitor scale.

Climate model simulations suggest that greenhouse gas emissions will make severe droughts more frequent by mid-to-late century unless emissions are curtailed. Fu emphasized that addressing this issue requires halting temperature increases through reduced greenhouse gas emissions.

The study received support from NOAA’s National Integrated Drought Information System and Climate Program Office and the National Science Foundation.