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mac
Joined: 07 Mar 1999
Posts: 17747
Location: Berkeley, California
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 Posted: Tue Aug 17, 2021 11:19 am Post subject: |
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| mrgybe wrote: | BEGINNING about 1,100 years ago, what is now California baked in two droughts, the first lasting 220 years and the second 140 years. Each was much more intense than the mere six-year dry spells that afflict modern California from time to time, new studies of past climates show. The findings suggest, in fact, that relatively wet periods like the 20th century have been the exception rather than the rule in California for at least the last 3,500 years, and that mega-droughts are likely to recur.
https://www.nytimes.com/1994/07/19/science/severe-ancient-droughts-a-warning-to-california.html |
As noted before, seldom in doubt, usually wrong. Today's news features the announcement that allocations of water from the Colorado River will be curtailed for the first time ever. Indeed, the drought is throughout the west, and unprecedented, despite the claims of apologists. It also highlights a very real problem in the west, the Colorado River and the California water system are both oversubscribed, and climate change is making things much worse.
There are some very good and thoughtful articles, one in the New Yorker "The Lost Canyon" that looks at the re-emergence of Glen Canyon, and another by Robert Glennon in "The Conversation." https://www.route-fifty.com/infrastructure/2021/08/colorado-river-basin-states-confront-water-shortages-its-time-focus-reducing-demand/184580/
To the specifics of climate change and its impact on making the drought so much worse, here are a few bits from the New Yorker:
| Quote: | According to a recent paper in Science, the drought that’s plagued the Southwest since the early two-thousands is already more acute than the worst stretch of the great drought. It’s also worse than an even greater drought that hit the region in the mid-eleven-hundreds and nearly as bad as the most severe dry spell in the record, which occurred in the late fifteen-hundreds. Indeed, the authors of the paper concluded, all of western North America, which includes northern Mexico, is currently on a “megadrought-like trajectory.” Withdrawals from Lake Powell and Lake Mead have helped mask the severity of the situation, but what happens next?
Park Williams, a climate scientist at U.C.L.A. and the lead author of the Science study, told me that, to researchers, the droughts indicated in the tree-ring record “were almost like mythical beasts, lurking there.” Those droughts, it’s believed, were caused by shifts in the temperature of the eastern Pacific, which produced air-circulation patterns that blocked storms from reaching the western part of the continent. Today, too, naturally occurring oscillations in sea-surface temperatures are keeping the West dry. But now there’s also climate change to contend with....
But this event isn’t only bad luck. It’s also a very straightforward effect of global warming.”
He went on, “Warmer air evaporates water out of soils and ecosystems more quickly. So every raindrop or snowflake becomes a bit less potent, because the atmosphere has this increasing thirst. And that means that as we go into the future, to get into a drought as bad as the one we’re in now, it’s going to take less and less bad luck, because human-caused warming is doing more and more of the heavy lifting.”
According to another study, published in the journal Water Resources Research, during the first fourteen years of the twenty-first century the average flow of the Colorado River was almost twenty per cent lower than it was during the twentieth century. The authors of this study, Brad Udall, of Colorado State University, and Jonathan Overpeck, of the University of Michigan, attributed a third of the decline to global warming. They predicted that, as temperatures continue to rise, the amount of water in the river will continue to drop. “It is imperative that decision-makers begin to consider seriously the policy implications of potential large-scale future flow declines,” they warned.
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Who you going to believe, the carbon industry or science? It won't change the future, but it will tell a lot about your values. |
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