A recent study by UCLA and NOAA indicates that rising temperatures heighten drought risks across the western United States, even during periods of average precipitation. Warm air increases evaporative demand, resulting in a significant elevation of drought severity due to evaporation rather than lack of rainfall. This marks a shift in our understanding of drought, necessitating a redefinition of its causes and impacts in light of climate change.
Recent research conducted by scientists from UCLA and NOAA reveals that high temperatures significantly influence drought conditions across the western United States, even during years with adequate snowfall and rainfall. This study, published in the journal “Science Advances”, emphasizes how warmer air is exacerbating drought effects in Colorado and other Western states, suggesting that evaporation has become a more critical factor than previously understood. Joel Lisonbee, a coauthor and regional drought information coordinator with NOAA, stated that the region must brace itself for increasing drought frequency and severity as global temperatures rise. The study elucidates that moisture essential for healthy vegetation derives from two primary sources: precipitation and the atmospheric demand for moisture. Higher temperatures amplify this atmospheric demand, termed “evaporative demand”, which refers to the rate at which moisture is removed from the soil and air. As air temperatures increase, this demand escalates, leading to more moisture being evaporated before it can precipitate back to the ground, inflicting significant stress on ecosystems even when precipitation levels appear normal. Professor Rong Fu from UCLA emphasizes the crux of the situation, highlighting that increased evaporation accounted for a staggering 61% of the drought severity in the drought period from 2020 to 2022, compared to only 39% attributed to reduced precipitation. Furthermore, historical comparisons indicate that from the year 2000 onward, the atmospheric thirst has rendered 66% of historically vulnerable Western land susceptible to drought caused solely by evaporation, a dramatic rise from 26% during the period from 1948 to 1999. In response to these findings, Lisonbee and his colleagues are reevaluating how drought is defined in contemporary discourse. They are considering whether to utilize historical data from the late 19th century or to adopt a shorter time frame that reflects more current climate realities. This redefinition aims to foster a deeper understanding of drought in the context of ongoing global warming.
The growing concern over drought conditions in the western United States has been exacerbated by climate change, with increasing temperatures leading to unprecedented evaporation rates. The term “megadrought” has been used to describe the ongoing extreme drought conditions, characterized by a significant increase in the area affected by drought since the turn of the century. This environmental crisis threatens ecosystems, agriculture, and water resources, necessitating a reevaluation of drought metrics and response strategies as climate change intensifies and becomes a driving force behind these severe weather patterns.
The findings of this landmark study underscore the dire implications of climate change on drought conditions in the western United States. As hotter temperatures elevate evaporative demand, the region faces the prospect of more frequent and intense droughts, regardless of precipitation levels. The need for a nuanced definition of drought that incorporates the realities of climate change has never been more urgent, highlighting the critical intersection of environmental science and public policy.
Original Source: coloradosun.com
