Tag: Park Williams

Meteorologists Warn ‘Megadrought’ in US Southwest is Worst in 1,200 Years

Sputnik – May 12, 2022

A new study has found that the 22-year-long water shortage plaguing the American Southwest and western Mexico is the region’s worst in more than a millennium – a phenomenon dubbed a “megadrought.”

The study, published in Nature Climate Change, found that soil moisture deprivation has exceeded that of a megadrought in the 16th century that was previously the region’s worst known drought.

It’s so bad that University of California Los Angeles geographer Park Williams, the study’s lead author, has warned it would take a prolonged shift in weather patterns to remedy things.

The researchers looked at tree rings to compare the present drought’s intensity with those of years past, since trees generally produce wider rings in wet years and narrower rings in drier years. They found that since 2000, the average soil moisture deficit was twice that of any drought of the past century, with nothing comparable being found until 1,200 years back.

The region has always been quite dry, of course, with four large deserts dominating the terrain and the rest being fairly arid. Indigenous civilization was well-adapted to the precarious conditions, but modern cities have been built without respect to climate – and may soon suffer the consequences.

Reservoirs created by hydroelectric dams, like the famous Hoover Dam outside Las Vegas, Nevada, that holds back Lake Mead, are reaching historic lows. The lake provides the City That Never Sleeps with its freshwater, but has suffered steady water loss since 1983, which has accelerated in recent years, requiring modifications to Hoover Dam’s turbines to allow it to continue producing electricity despite the low water level.

https://sputniknews.com

The US Southwest is hitting megadrought status

– February 14, 2022

About half of the contiguous US is currently experiencing moderate to extreme drought—including almost all of the West. That shouldn’t come as a surprise, as widely pervasive drought has been present for quite a while now in this region, where major reservoirs like Lake Powell and Lake Mead are hovering around all-time low-water levels. But how does this ongoing drought compare to the past? After all, the region is no stranger to dry stretches.

A 2020 paper examined the 2000-2018 data in the context of a tree ring reconstruction going back to the year 800 and stretching from Southern California to Wyoming. That team found that this was likely the second-driest period in the record, beat out only by a megadrought in the late 1500s.

At the time, the paper’s authors guessed that good precipitation in 2019 would be enough to end the extended drought. But instead, a particularly wicked 2021 kept the drought alive. As a result, three of those researchers—UCLA’s Park Williams and NASA’s Benjamin Cook and Jason Smerdon—decided to update the numbers through 2021.

The most mega

The term “megadrought” isn’t some sensationalist moniker from bad television; it’s a term for the handful of two- to three-decade Southwestern droughts in the past millennium or so—some with history-defining impacts on the civilizations who lived there at the time.

With the analysis updated, 2000-2021 ranks as the driest such 22-year period in the data going back to the year 800. The megadrought years of 1571-1592 slip into second place. (Though the error bars on the two periods overlap.)

Between 2000 and 2021, 18 of those years saw soil moisture below the long-term average. Only two past megadroughts meet that level of consistent dryness. The years 2002 and 2021 rank as the 11th and 12th driest years in the whole record—and it has been three centuries since a drier year occurred. And although some megadroughts were focused in a particular region, the drought of the last two decades has been widespread across the West. That’s what you would expect to see from a drought driven more by global warming than by precipitation patterns.

To estimate the contribution of climate change, the researchers repeated their analysis of climate models run with and without warming temperatures. Their previous work had estimated that 46 percent of the severity of the 2000-2018 drought was due to human-caused warming. For 2000-2021, they get a similar answer of 42 percent despite using a new generation of climate model simulations.

https://arstechnica.com

Western U.S. Is Facing the Worst Megadrought in Over 1,200 Years

Strange Sounds – Apr 18, 2020

In the 1930s, the United States was suffering from the most severe drought in its history, the “Dust Bowl.”

And be prepared to bite the dust once again, because scientists think the Dust Bowl is coming back for a second round. And this time for it could even last during decades.

A new study has used 1,200 years of tree-ring data, soil moisture records, and dozens of climate models to describe the ever-lengthening string of dry spells that have hit the western United States and northern Mexico over recent decades. 

They found that a chronic drought has been lurking around the southwestern US and northern Mexico since at least the year 2000.

The spell of aridity has already become so severe it’s already surpassed three of the four notoriously arid megadroughts of Medieval times.

The researchers were uncertain about the extent of the fourth Medieval megadrought, which spanned from 1575 CE to 1603 CE, although they note the current drought is affecting wider areas more consistently than any megadrought since 800 CE.

“We now have enough observations of current drought and tree-ring records of past drought to say that we’re on the same trajectory as the worst prehistoric droughts,” stated lead author Park Williams.

https://strangesounds.org