Jun 25, 2021 07:53 PM
(This post was last modified: Jun 25, 2021 07:53 PM by C C.)
Half the country is facing an apocalyptic summer
https://www.livescience.com/western-drou...fires.html
INTRO: About 91% of the West was in drought as of June 22, with 55% experiencing extreme or exceptional drought, while two back-to-back heat waves exacerbated the drying of soils and vegetation, increasing the potential for wildfires. Meanwhile, water supplies are dwindling: Lake Mead, the reservoir formed by the Hoover Dam, is the lowest it has been since the 1930s when it was first filled, and California's reservoirs are 50% lower than usual for this time of year, according to the Associated Press.
The current conditions are part of a 22-year-long drought in the western U.S., the likes of which have not been seen for more than 400 years prior to 2000. But this summer is likely to eclipse the drought of the last two decades, said Benjamin Cook, a climate scientist at the NASA Goddard Institute for Space Studies.
"Even in the context of those last 20 years of drought this year really stands out," Cook told Live Science. "For the Southwest, it's very likely to be the worst single year of drought since 2002."
In the immediate term, drought in the West is promoted by La Niña conditions, which were in place through winter 2020-2021, according to Scott Handel, a meteorologist at the National Oceanic and Atmospheric Administration (NOAA). During La Niña, surface temperatures in the eastern Pacific Ocean are cooler than usual, which tends to promote drier weather in the West. This natural variation in Pacific temperatures is now in a neutral state (neither La Niña or El Niño), Handel told reporters on June 17, and a reversal to El Niño conditions — which bring more moisture to the Southwest — is not likely through the winter.
Extended drought is part of the history of the U.S. West. Modern meteorological records in the West go back little more than a century, but tree rings hold a longer record of wet and dry years. These data, stretching back 2,000 years in some cases, reveal that long, deep droughts occur even without the influence of climate change... (MORE)
Unexpected: desert plants are struggling in higher heat
https://www.scientificamerican.com/artic...gher-heat/
EXCERPTS: . . . Recent research suggests dry lands are at a breaking point — and it's more closely tied to temperature than previously thought. [...] "Our analysis suggests these ecosystems may have crossed an ecological threshold," they said, describing a breakdown in the relationship between precipitation and vegetation cover beginning around 1999.
In the Sonoran Desert and nearby landscapes, the scientists found, vegetation cover declined much more sharply than drought or wildfires alone could explain. Satellite observations between 1984 and 2017 showed "widespread" declines in perennial vegetation cover, the researchers wrote, especially in lowland deserts.
In the lowlands, modeling revealed that temperature explained much of the desert's vegetation change, according to the study. Rising heat was also the best explanation for vegetation declines over the long term, as precipitation and wildfires have swung wildly from year to year.
The importance of heat surprised even the researchers. "Many plant species in desert ecosystems have adaptations that allow them to withstand high temperatures, making this observation somewhat unexpected," they wrote.
More research is needed to explain the mechanism behind that relationship, the authors added. One possible reason is that hotter weather makes water evaporate more quickly, creating even worse water stress on plants during the hot summer months. The implications of the research could be dire... (MORE - details)
https://www.livescience.com/western-drou...fires.html
INTRO: About 91% of the West was in drought as of June 22, with 55% experiencing extreme or exceptional drought, while two back-to-back heat waves exacerbated the drying of soils and vegetation, increasing the potential for wildfires. Meanwhile, water supplies are dwindling: Lake Mead, the reservoir formed by the Hoover Dam, is the lowest it has been since the 1930s when it was first filled, and California's reservoirs are 50% lower than usual for this time of year, according to the Associated Press.
The current conditions are part of a 22-year-long drought in the western U.S., the likes of which have not been seen for more than 400 years prior to 2000. But this summer is likely to eclipse the drought of the last two decades, said Benjamin Cook, a climate scientist at the NASA Goddard Institute for Space Studies.
"Even in the context of those last 20 years of drought this year really stands out," Cook told Live Science. "For the Southwest, it's very likely to be the worst single year of drought since 2002."
In the immediate term, drought in the West is promoted by La Niña conditions, which were in place through winter 2020-2021, according to Scott Handel, a meteorologist at the National Oceanic and Atmospheric Administration (NOAA). During La Niña, surface temperatures in the eastern Pacific Ocean are cooler than usual, which tends to promote drier weather in the West. This natural variation in Pacific temperatures is now in a neutral state (neither La Niña or El Niño), Handel told reporters on June 17, and a reversal to El Niño conditions — which bring more moisture to the Southwest — is not likely through the winter.
Extended drought is part of the history of the U.S. West. Modern meteorological records in the West go back little more than a century, but tree rings hold a longer record of wet and dry years. These data, stretching back 2,000 years in some cases, reveal that long, deep droughts occur even without the influence of climate change... (MORE)
Unexpected: desert plants are struggling in higher heat
https://www.scientificamerican.com/artic...gher-heat/
EXCERPTS: . . . Recent research suggests dry lands are at a breaking point — and it's more closely tied to temperature than previously thought. [...] "Our analysis suggests these ecosystems may have crossed an ecological threshold," they said, describing a breakdown in the relationship between precipitation and vegetation cover beginning around 1999.
In the Sonoran Desert and nearby landscapes, the scientists found, vegetation cover declined much more sharply than drought or wildfires alone could explain. Satellite observations between 1984 and 2017 showed "widespread" declines in perennial vegetation cover, the researchers wrote, especially in lowland deserts.
In the lowlands, modeling revealed that temperature explained much of the desert's vegetation change, according to the study. Rising heat was also the best explanation for vegetation declines over the long term, as precipitation and wildfires have swung wildly from year to year.
The importance of heat surprised even the researchers. "Many plant species in desert ecosystems have adaptations that allow them to withstand high temperatures, making this observation somewhat unexpected," they wrote.
More research is needed to explain the mechanism behind that relationship, the authors added. One possible reason is that hotter weather makes water evaporate more quickly, creating even worse water stress on plants during the hot summer months. The implications of the research could be dire... (MORE - details)