La Niña is about to take the Southwest drought from bad to worse
More than 94% 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 hydro power generation in coming years.
Though summer rainfall brought some relief to the Southwest,
the unrelenting drought there is about to get worse with La Niña on the
horizon, according to David DeWitt, director at the National Oceanic and Atmospheric
Administration's Climate Prediction Center.
"As we move into fall, from October on, the Southwest
US, based on all the best information that we have, they're going to see
persistent intensification and development of drought," DeWitt told CNN.
"There's, at this point, not any indication that they'll see drought
relief."
La Niña is a natural phenomenon marked by cooler-than-average sea surface temperatures across the
central and eastern Pacific Ocean near the equator, which causes shifts in
weather across the globe. In the Southwest, La Niña typically causes the jet
stream upper-level winds that carry storms around the globe -- to shift
northward. That means less rainfall for a region that desperately needs it. ( Image credit USDA)
NOAA's latest projections show a 70& to 80% chance of La Niña emerging during the
Northern Hemisphere winter season. With La Niña conditions coupled with warming
temperatures, DeWitt said the Southwest will see enhanced evaporation that will
intensify drought in certain places.
"The net water balance going forward, from this point
as the summer monsoon ends, is that we're going to see conditions continue to
dry out," DeWitt said. "Places that have droughts will kind of
persist or intensify, and places that don't have drought right now because it
was recently ameliorated, we expect drought is going to redevelop."
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, told CNN.
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.
Projections released Wednesday show a 66% chance that
water levels at Lake Mead could drop to a level that would trigger even deeper
cuts, potentially affecting millions of people in California, Arizona, Nevada
and Mexico.
The agency also projected a 3% chance that Lake Powell next
year could drop below the minimum level needed for the lake's Glen Canyon Dam
to generate hydroelectricity. In 2023, the chance of a shutdown grows to 34%.
Drought and blistering heat has fueled major wildfires in
the West this summer. According to Philip Higuera, fire ecology professor at
the University of Montana, warming temperatures caused the record-low level of
rain and humidity that dried out trees and vegetation, which in turn ignited
more wildfires.
"You can have the same amount of vegetation in a
forest, but if it's wet, it's not available to burn," Higuera previously told CNN. "These regions across the West that
have record dry fuels, that makes more vegetation available to burn -- so
basically, more of the forest is participating in these fires."
Oregon's Bootleg Fire, which started in July, became the
second largest wildfire in the country this year; meanwhile, California battled
the Dixie Fire -- the largest in the US this year and second-largest in state
history. Currently, firefighters are battling the lightning-sparked KNP
Complex and Windy fires, which are threatening Sequoia National Park and
national forest.
According to Mankin, the longer-term fate of the Western
drought remains bleak. What's needed now, he said, is several years of rain and
mountain snow to replenish the draining reservoirs and rivers.
That becomes more unlikely as the climate crisis worsens.
Experts say the West will only continue to see more droughts like the present
one in the years to come and only rapid, immediate cuts to fossil fuels can
halt this harsh trend.
"Global warming is making the atmosphere over the West
warmer and thirstier, such that even the rain and snow that was once normal may
be too little to quench it," Mankin said. "The only way to stop the
kind of atmospheric demand increases that have made this drought so impactful,
is to stop combusting fossil fuels."
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This valuable article appeared in CNN all credits to USDA and CNN writer
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