Southwest Experiences Worst Drought In More Than 1200 Years
February 15, 2022
A new study unveils that the Southwest is currently experiencing the worst drought since the 800s. The Southwest has been enduring drought for the past 22 years and is now undergoing a megadrought; which is a drought occurring for twenty years or more.
The paper titled “Rapid Intensification of the Emerging Southwestern North American Megadrought in 2020 - 2021” was published in the journal of Nature Climate Change. The previous time such a megadrought occurred in the Southwest was in 1500s. However, the current drought is the worst since the 800s, according to the study. The study attributed the megadrought to higher temperatures and low precipitation from summer 2020 till summer 2021 in the region.
The lead author of the study and geographer, Park Williams, from the University of California Los Angeles, said that he is doubtful that a single wet year could turn back the time on the effects of the drought and it may take multiple wet years as dry conditions are likely to press on. Jason Smerdon and Benjamin Cook from the Columbia Climate School co-authored the study. To calculate the severity of drought, the researchers analyzed the tree rings which can provide valuable information about soil moisture levels. High soil moisture deficits were associated with periods of drought and the researchers confirmed this by comparing the findings with historical climate records. The average soil moisture deficit was double that of any drought in the 1900s and is greater than any drought since the 800s.
The researchers studied the area from southern Montana and to northern Mexico, and from the Pacific Ocean to the Rocky Mountains and concluded that megadroughts were commonplace between 800 to 1600. The region has been enduring water availability issues well before the effects of human induced climate change was observed and became widespread knowledge in recent times. The study also revealed that the current drought would have happened regardless of human caused climate change albeit the effects might not have been as severe. Around 42% of the soil moisture deficit since 2000 was associated to human induced climate change. The temperatures in the region from 2000 to 2021 was 0.91 degrees Celsius, 1.64 degrees Fahrenheit, higher than the 1950 to 1999 average.
Williams said “Without climate change, the past 22 years would have probably still been the driest period in 300 years. But, it wouldn’t be holding a candle to the megadroughts of the 1500s, 1200s or 1100s.”
According to the US Drought Monitor, as of 10th of February 2022, 95% of the western US was undergoing drought. Lake Mead and Lake Powell, two of the largest reservoirs in North America, hit their lowest water levels in summer 2021, since the record-keeping started. As a response to the low water levels in the reservoirs, both of which are served by the Colorado River, federal officials cut the supply to Southwest states, in August 2021. In addition, in October 2021, the California Governor, Gavin Newsom, declared a drought emergency and asked the residents of California to reduce the water usage by 15%.
Williams said that the water preservation efforts will have to go further than the periods of drought to ensure adequate supply of water as the effects of climate change are getting more pronounced, although these efforts may help in the interim period.