The extreme heat and dry conditions of the past few years pushed what was already an epic, decades-long drought in the American West into a historic disaster that bears the unmistakable fingerprints of climate change. The long-running drought, which has persisted since 2000, can now be considered the driest 22-year period of the past 1,200 years, according to a study published Monday in the journal Nature Climate Change.

Previous work by some of the same authors of the new study had identified the period of 2000 through 2018 as the second-worst megadrought since the year 800 — exceeded only by an especially severe and prolonged drought in the 1500s. But with the past three scorching years added to the picture, the Southwest’s megadrought stands out in the record as the “worst” or driest in more than a millennium.

“Without climate change, this would not be even close to as bad as one of those historical megadroughts,” said Park Williams, a climate scientist at the University of California at Los Angeles. “The thing that is really remarkable about this drought period is that temperatures have been warmer than average in all of the years but one.”

The double whammy of searing heat and persistent drought in recent years reflects the steady increase in global temperatures brought on by the burning of fossil fuels. The authors attribute 19 percent of the severe 2021 drought, and 42 percent of the extended drought since the 21st century began, to human-caused climate change.

This giant climate hot spot is robbing the West of its water

Scientists refer to this combined hot and dry effect as “aridity” — a warm and thirsty atmosphere that can pull moisture from soil and plants, melt snow, and intensify heat waves.

“All of the climate models agree that when greenhouse gases go into the atmosphere and temperatures rise, that’s going to enhance the ability of the atmosphere to pull water out of ecosystems,” Williams said.

This “background drying” brought on by a warmer atmosphere can dwarf occasional wet or cool periods. For example, the Southwest’s 2021 drought maintained its grip despite robust monsoon rains and record summer precipitation in some areas, in part because of extraordinary heat waves early last summer, and generally above-average temperatures.

The study’s tree-ring record also provides a sobering view of what is possible in the West. “The tree rings tell us that there can actually be very, very extreme dryness in the West without the help of climate change at all,” Williams said. “Even without climate change, we can have monumentally severe and long-lasting droughts.”

The study finds that the 21st century has been substantially drier than the previous five decades, with 8.3 percent less precipitation, and nearly 1 degree Celsius (1.8 Fahrenheit) warmer than the period from 1950 to 1999.

The American West’s drought isn’t a disaster. It’s our new, permanently arid normal.

And scientists have made clear that future warming could bring even more crippling and frequent droughts. Last summer, a report by the U.N. Intergovernmental Panel on Climate Change found that even as global warming can bring more extreme rainfall and flooding in some areas, it can also fuel more intense drought in many regions.

That analysis found that at the current warming trajectory, droughts in drying regions that previously occurred only once every 10 years are now happening about 1.7 times per decade, on average. If the Earth warms 2 degrees Celsius, scientists expect those once-rare events to take place roughly 2½ times per decade, on average.

But the West’s most recent megadrought isn’t just written in scientific data. It has manifested in the shrinking water levels of Lake Mead and Lake Powell, which last summer reached their lowest on record. These reservoirs have declined during the 21st century with rising temperatures, despite intermittent wet years.

The intensifying drought looks to continue in 2022 — unless a miraculous spring season brings a return of the storm track and moisture-rich atmospheric rivers.

Fueled by climate change, costly Southwest drought isn’t going away

While the study covers only the period through 2021, drought conditions have taken a turn for the worse in 2022. After a promising start to the wet season in December, unusually dry conditions have persisted over much of California since January.

California’s snowpack declined to just 73 percent of normal as of Monday, after being at 160 percent of normal in December.

The Central Sierra Snow Lab run by the University of California at Berkeley tweeted that its snowpack lost 5 percent of its water content amid unusually warm weather over the past week. At its monitoring site, the snowiest December on record has been followed by a record streak of 37 days without precipitation.

The parched conditions laid the groundwork for a recent record-setting winter heat wave in California.

From Wednesday through Sunday, the National Weather Service in Los Angeles issued the first heat advisory on record during the winter months in Southern California. Scores of record high temperatures were set, from San Diego to San Francisco.

Brush fires raged in Southern California amid record heat, worsening drought

Death Valley soared to 94 degrees on Feb. 11, its highest temperature recorded so early in the season.

The hot, dry weather, combined with gusty winds, fueled several brush fires in Southern California late last week. California has seen more than 12 million acres burn in the past decade, and 18 of the top 20 largest wildfires in state history have occurred in the past two decades.

Forecasters at the National Weather Service predict drought conditions to persist through the spring.

The authors of the paper also see no end in sight to the West’s arid reality.

“This drought will very likely persist through 2022,” they wrote, “matching the duration of the late-1500s megadrought.”

Williams said that tree-ring records do provide some reason for hope — megadroughts do eventually end when the rains return. Those rains are arriving in increasingly intense bursts as the atmosphere warms.

“The way you get out of droughts in the West is probably changing,” he said. Droughts may end abruptly during extremely wet years, like 2017, but then quickly reverse course again into another multiyear dry spell.

Brady Dennis and Jason Samenow contributed to this report.

Source: https://www.washingtonpost.com/weather/2022/02/14/southwest-megadrought-worst-1200-years/

The post Southwest drought is the most extreme in 1,200 years, study finds first appeared on Garner Ted Armstrong Evangelistic Association.

William Brangham:

The Colorado River is a critical source of water for the Western United States, but a mega-drought, one significantly exacerbated by climate change, is jeopardizing that river’s future, how that water gets used, and threatening longstanding agreements between states.

Miles O’Brien has our report.

It’s part of our coverage on how climate change is creating a tipping point for the U.S. and the world.

Miles O’Brien:

This is where the shortage meets the soil, Pinal County, Arizona, desert farmland between Phoenix and Tucson, lifelong home for farmer Nancy Caywood.

Nancy Caywood, Farmer:

My family has been farming in this area for 91 years. My grandfather bought this farm, 255 acres.

Miles O’Brien:

They grow alfalfa and cotton, both thirsty crops, which are not doing well right now.

Nancy Caywood:

This is the drought in action right here. I have never seen it this bad before.

Miles O’Brien:

Much of her water comes from canals that are filled by the Gila River, a tributary of the Colorado River. But in April of 2021, the water stopped flowing.

Nancy Caywood:

We don’t know when we will see water in here again.

Miles O’Brien:

Same goes for farmers in Pinal County who draw water directly from the Colorado River. When the U.S. government declared an official shortage for the river in August, farmers who depend on it were also drastically cut back.

Almost 1, 500 miles’ long, the Colorado winds its way through seven states and into Mexico. This river basin is filled with lush natural ecosystems. It transforms about 5.5 million acres of barren desert into fertile farmland; 40 million people are sustained by this water.

It’s one of the most heavily utilized rivers in the world, and it starts here, as a deep blanket of snow high in the Rocky Mountains of Wyoming, Utah, and Colorado.

Hydrologist Ben Livneh is an assistant professor at University of Colorado Boulder.

Ben Livneh, University of Colorado Boulder: Most of the of the water in the Colorado River starts as snowpack, and one of the reasons is that mountains act as these big catchments of precipitation.

Miles O’Brien:

But around the year 2000, a drought took hold and has not let go. This means less snow on those peaks in the Rockies year after year, and thus a steady reduction of water to feed the river.

The two largest reservoirs in the river basin, Lake Mead and Lake Powell, are now at all-time low levels. Climatologist Park Williams is an associate professor at UCLA. He uses tree rings to study the ancient climate.

Park Williams, UCLA:

The 2000s drought in the Colorado River Basin and across the Western United States has been as dry as any other 22-year period in the last millennium. The drought that we’re in today is not going to last forever, that it will break at some point when we have a string of really good luck years.

Miles O’Brien:

But the climate emergency has changed the odds. The global temperature is about two degrees Fahrenheit higher than it was before the Industrial Revolution.

Park Williams:

If climate change hadn’t happened, the West would still be in a drought, but the severity of the drought is undoubtedly worse because of climate change.

Miles O’Brien:

Here’s why. Warmer temperatures mean drier air. As the snowpack shrinks, it sheds water vapor into the atmosphere. A larger amount of snow melts into liquid water and rapidly evaporates in this warmer climate. Now the soil is dryer than usual.

Park Williams:

This causes the soils to act like a very dry sponge, and the next precipitation events that occurs on top of that dry sponge is going to work to refilling the soil sponge, as opposed to refilling our rivers and reservoirs.

Miles O’Brien:

This precious resource is allocated based on a 1922 agreement called the Colorado River Compact. Once the river basin states agreed on their fair shares, they each established a seniority system, first in time, first in right.

Ben Livneh:

There’s kind of a hierarchy of water rights. That means that people who gained access to the river first, they have what we would call a senior water right.

Miles O’Brien:

Colorado River water first came to Pinal County in the mid-1980s, upon completion of the Central Arizona Project, a network of canals that spans more than 300 miles across the desert.

It puts farmers here at the bottom of the seniority list, making them the first to go dry in the midst of this mega-drought.

Will Thelander, Farmer:

So, over the years, we have had to adapt to different whatever we can make money at, basically. So, on this farm, it’s really close to a bunch of dairies, and they need a bunch of feed.

Miles O’Brien:

Will Thelander is a third-generation farmer in Casa Grande. He and his family are part of an experiment in using their dwindling allocation of water on crops that demand less of it.

Will Thelander:

Here’s the guayule field. So you can see it’s in a nice bloom, and this crop hasn’t been watered for about two weeks.

Miles O’Brien:

They have planted a 40-acre tract of guayule, a plant that thrives in the desert and contains a milky latex that can be used to formulate rubber.

An acre can produce enough to make 50 tires. Bridgestone is working out the production kinks at this pilot plant, while Thelander does the same at this pilot plot.

Will Thelander:

With this crop, using half as much water as the corn, our water will last twice as long here. So that’s why the crop is so promising, and we really hope it takes off.

Miles O’Brien:

But for Nancy Caywood, the story is different. She can’t afford the cost of the new equipment required to harvest crops that need less water. She says she can hold onto the family farm for a year, but:

Nancy Caywood:

Eventually, the money runs out. You can’t pay the water and the taxes anymore. So it’s not your best interest to try to keep the land. Your best interest is to probably go ahead and sell. And it’s heart-wrenching to think that, but it’s true.

Miles O’Brien:

It would be the end of an era here, and maybe the beginning of a new one. Her neighbors recently sold their land, and it’s now a solar farm. Caywood has been approached by an energy company as well.

There is little to suggest this trend will reverse anytime soon. For years, humans overspent the Colorado River, and nature covered the overdrafts. But now the climate emergency has insured the bill has come due.

For the “PBS NewsHour,” I’m Miles O’Brien in Phoenix.

Source: https://www.pbs.org/newshour/show/unrelenting-drought-leaves-millions-who-rely-on-colorado-river-facing-an-uncertain-future

The post Unrelenting drought leaves millions who rely on Colorado River facing an uncertain future first appeared on Garner Ted Armstrong Evangelistic Association.