Much of the Western half of the United States is in the grip of a severe drought of historic proportions. Conditions are especially bad in California and the Southwest, but the drought extends into the Pacific Northwest, much of the Intermountain West, and even the Northern Plains.
what is happening?
Global scientists reported in August that due to the climate crisis, droughts that may have occurred only once every decade or so now happen 70% more frequently. The increase is particularly apparent in the Western US, which is currently in the the throes of a historic, multiyear drought that has exacerbated wildfire behavior, drained reservoirs and triggered water shortages.
More than 92% of the West is in drought this week — a proportion that has hovered at or above 90% since June — with six states entirely in drought conditions, according to the US Drought Monitor. On the Colorado River, Lake Mead and Lake Powell — two of the country’s largest reservoirs — are draining at alarming rates, threatening the West’s water supply and hydropower generation in coming years.
NOAA published a report this week on the Southwest’s historic drought, addressing a key question of when it might end. The answer, according to the report, is that the current drought could last into 2022 — or potentially longer.
“More widely, my guess is that for much of the West, the current extent and magnitude of this drought is locked in until at least mid-2022,” Justin Mankin, assistant professor of geography at Dartmouth College and co-lead of NOAA’s Drought Task Force
What are the causes of this drought?
The NOAA report concluded that climate change-fueled drought will continue to worsen and impose greater risks on the livelihoods and well-being of over 60 million people living in the Southwest, as well as the larger communities that rely on their goods and services.
“This has big implications for drought mitigation measures for different water districts, many of which are working hard not only to manage the impacts of this drought, but to invest in longer-term adaptive measures to be resilient to more droughts like this in the future,” Mankin said. “Given scant resources to do both, these water districts need our support.”
The nation’s largest reservoirs, Lake Powell and Lake Mead, are at record-low levels. Both are fed by the drought-ravaged Colorado River watershed, and supply drinking water to 40 million people and irrigation to rural farms, ranches and native communities.
The Bureau of Reclamation in August declared a water shortage on the Colorado River for the first time, triggering mandatory water consumption cuts for states in the Southwest beginning in 2022.
For weather and climate experts, the fingerprints of the climatic phenomenon known as “La Niña”, which began last year, are unmistakable. This phenomenon arises from a thermal anomaly of tropical surface waters in the central Pacific Ocean, characterized by an abnormally low water temperature.
It generally means drier and warmer conditions in the southern half of the United States, and wetter weather in the northern half. Scientists confirm that most of the 20 strongest La Niña events that occurred over the past 70 years, formed drier than usual conditions in the southern states.
Recent National Oceanic and Atmospheric Administration projections indicate that this winter will lead to below-average rainfall in the region, with warmer-than-average temperatures.
This means that the current drought will continue in the southwestern United States at least until the first months of next year, and possibly longer, and that the water scarcity crisis will worsen further in the near future.
What is the role of climate change in all of this?
Many scientific studies link the exceptionally high temperatures that were recorded in the southwestern United States last summer with global warming, especially since most climatic scenarios indicate that extreme and acute phenomena such as droughts and heat waves have increased in intensity and frequency.
These conditions lead to acceleration of evaporation and increased pressure on water sources and persistent greenhouse gas emissions, even in rainy seasons, make rainfall less than average, leading to an intensification of droughts. The experts of the World Meteorological Organization stress that the El Nina phenomenon, like other natural phenomena, will not be spared the effects of climate change.
For all these reasons, forecasts suggest that the southwestern regions of the United States will continue to suffer from the severe drought that it has suffered during the past several years.
This climatic pattern is expected to extend at the beginning of next year to the south-central and southeast, including Florida, where forecasts indicate that the percentage of the probability of precipitation in the southern half this winter will be between 40% and 60% of the normal average.
Sources:
Map: https://droughtmonitor.unl.edu/CurrentMap.aspx
https://edition.cnn.com/2021/09/24/us/southwest-drought-forecast-climate-change/index.html