The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉
Main Topic: Is California Still in a Megadrought?
Dear Diary. Before La Niña rains came that alleviated California’s mega drought during the winters of 2022-23 and 2023-24, that state was described as being in a very long term megadrought. Large reservoirs were drying up threatening California’s lucrative and essential agriculture sector. As of the summer of 2024, most of California’s reservoirs are doing O.K. So, is that megadrought over?
Not really reading the following article from the Los Angeles Times (Please hit the link to see charts within the article that I did not repost.):
The American West’s last quarter-century ranks as the driest in 1,200 years, research shows
Fish carcasses lie on dried mud on the shore of Lake Mead in 2022. The reservoir near Las Vegas is the largest on the Colorado River and stores water for Nevada, Arizona, California and Mexico.
(Gina Ferazzi/Los Angeles Times)
By Ian James Staff Writer
Graphics by Sean Greene
July 30, 2024 3 AM PT
Three years ago, climate researchers shocked drought-weary Californians when they revealed that the American West was experiencing its driest 22-year period in 1,200 years, and that this severe megadrought was being intensified by global warming.
Now, a UCLA climate scientist has reexamined the data and found that, even after two wet winters, the last 25 years are still likely the driest quarter-century since the year 800.
”The dryness still wins out over the wetness, big time,” said UCLA professor Park Williams.
The latest climate data show that the years since 2000 in western North America — from Montana to California to northern Mexico — have been slightly drier on average than a similar megadrought in the late 1500s.
Williams shared his findings with the Los Angeles Times, providing an update to his widely cited 2022 study, which he coauthored with scientists at Columbia University’s Lamont-Doherty Earth Observatory.
The new findings reveal that even the unusually wet conditions that drenched the West since the start of 2023 pale in comparison to the long stretch of mostly dry years over the previous 23 years.
Megadroughts over the centuries
Since 2000, western North America has experienced the driest 25-year period in at least 1,200 years — just slightly drier than a megadrought in the late 1500s.
And that dryness hasn’t been driven by natural cycles alone. Williams and his colleagues have estimated that a significant portion of the drought’s severity — roughly 40% — is attributable to warming driven by the burning of fossil fuels and rising levels of greenhouse gases. The warming that has occurred in the region, an increase of more than 2.5 degrees Fahrenheit since recordkeeping began more than a century ago, has intensified the dry conditions, making the latest megadrought significantly more severe than it would be without climate change.
But are we still in a megadrought? How will we know when the megadrought is finally over?
Williams said those questions will take some time to answer, and the conclusions will only become clear in hindsight.
“Based on the definition of megadrought that we’ve been using, which involves looking at the past 10 years to see if dry or wet conditions prevailed, we can only see the termination of a megadrought in hindsight,” Williams said. “If the next few years are on average wet, that will mark the end of the megadrought. If they’re dry, the megadrought will continue.”
A boat motors across Lake Powell on the Arizona-Utah border in 2021. The reservoir, the second-largest on the Colorado River, has declined dramatically over the last 25 years. (Luis Sinco / Los Angeles Times)
Williams and his colleagues track the severity of drought using a 10-year running average of summer soil moisture throughout western North America.
They compare this century’s drought and other megadroughts using ancient records captured in the growth rings of trees. Wood cores extracted from thousands of trees provide data for about 1,600 sites across the region, enabling scientists to reconstruct the soil moisture centuries ago.
A comparable megadrought occurred from 1571 to 1593, ending after 23 years. Williams said his latest review of data through June shows that the last 25 years, when compared with the late 1500s, have been “ever so slightly drier.”
Comparing the West’s megadroughts
The megadrought beginning 2000 in the American West has been similar in severity to a 23-year megadrought in the 1500s. Research shows global warming has intensified the extreme dryness over the last 25 years.
“It’s important to recognize that even the megadroughts in our tree-ring reconstruction had extremely wet years within them, wet years like 2023,” Williams said. “Megadroughts can take brief breaks.”
Whether this megadrought continues or eases will become clearer over the next year or two, he said.
If wetter-than-average conditions continue, he said, it might be the case that the megadrought already ended after 23 years in 2023. On the other hand, it might be that the rest of 2024 turns out to be drier than average and is followed by more dry years, in which case the megadrought would still be underway.
A visitor surveys the Colorado River and Canyonlands National Park at Dead Horse Point near Moab, Utah. (Luis Sinco/Los Angeles Times)
Williams said his research shows that much of the drought’s severity has been driven by the West’s extreme natural variability, which he likens to a yo-yo going from wet to dry. But these variations are now superimposed on a drying trend with climate change, he said, a “shifting baseline” that is making droughts more severe and longer lasting.
Williams said it’s very likely the megadrought since 2000 wouldn’t be on par with the long droughts of centuries ago if it weren’t for the warmer temperatures being unleashed by human-caused climate change.
“We don’t know whether or not the next 10 years is going to be a good luck sequence or a bad luck sequence,” Williams said. “But we do know, based on climate modeling and math and logic, that as long as the atmosphere continues to get warmer, then the chances that the next 10 years are drier than average will be higher than they were in the last century.”
Western megadrought is worst in 1,200 years, intensified by climate change, study finds
Feb. 14, 2022
Scientists and policy experts widely agree that adapting to aridification driven by climate change in the western U.S. will require major changes in how limited water supplies are managed for farms, cities and the environment.
“Regardless of what happens in the next few years, which will be dictated mostly by the randomness of weather, as the atmosphere continues to warm we should expect it to continue to degrade our water supply,” Williams said. “A warmer atmosphere is a thirstier atmosphere, and without a compensating increase in precipitation, which has not occurred, humans and ecosystems will be left with less water.”
That will require a continued focus on curbing unsustainable overuse of water from rivers and aquifers, he said. “Even during periods of good luck and wetness, we cannot forget that the long-term average is drifting towards being drier.”
California farmers set to cut use of Colorado River water, temporarily leaving fields dry
July 11, 2024
Williams said the data suggest that by 2100, the region will most likely have experienced one or two additional megadroughts, which could be even more severe.
And yet, looking to the future, the biggest source of uncertainty in the climate projections is how people will respond in addressing climate change.
“We, the burners of fossil fuels, actually have a huge ability to control the climate over the rest of this century. The climate of the 2090s is very sensitive to what we do with fossil fuels in the next 20 to 30 years,” Williams said. “We need to reduce carbon emissions in order to stabilize the climate.”
More to Read
- El Niño makes an exit, but La Niña could bring dry conditions back to California
- June 14, 2024
- The U.S. Drought Monitor is a critical tool for the arid West. Can it keep up with climate change? June 3, 2024
- How is climate change affecting heat waves in California and the West?
- June June 2, 2024
Here are more “ETs” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Here is new July 2024 climatology:
Here is More Climate News from Thursday:
(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)