Something Amazing and Frightening Could Be Unfolding Before Our Eyes
Over the past two decades the American southwest has been hit by droughts. That hasn't stopped the region from growing with the arrival of newcomers, especially retirees from the northern states. The droughts - well, they come and they go. Until now.
Researchers know that this region, the southwest and the prairie, have a history of megadroughts of a duration between 60 and 80 years at a stretch. And scientists are now warning that the region may be in the opening stages of megadrought right now.John Wesley Powell, the one-armed US army civil war veteran who led the first white expedition down the Colorado River through the Grand Canyon – a daring boat run in 1869 – later became an ethnographer who wrote a prescient 1878 government paper titled: Report on the Lands of the Arid Regions of the United States. In it, he unflinchingly described the scarcity of water, and summarized that much of the American south-west, if it must be settled, should be settled lightly and modestly. Overpopulate it, and it will be unforgiving.
Wallace Stegner, the dean of western writers, observed, “As a government scientist, Major Powell was now defying ignorance. He was taking on vested interests and the vested prejudices by which they maintained themselves.”
(aside - I love that phrase, "the vested prejudices by which they maintained themselves." Doesn't that fit today's fossil fuel giants and their political minions?)
Instead of heeding Powell's warnings the US government chose to build two mega-dams on the Colorado River, the Hoover and Glen Canyon dams.Farmers greened the desert. Cattle grazed the valleys. High voltage lines lit up casinos, stadiums and homes, keeping them warm in winter, cool in summer. It felt almost providential, ordained by God.
Today, the Colorado River provides water for 40 million people in seven states, but stricken by a devastating drought, it’s not what it used to be. Lake Mead and Lake Powell are both at about 30% capacity, down more than 140 feet from “full pool”. If the lakes go much lower, the dams will be unable to generate power. The snow pack in the Rocky Mountains – that feeds the 25 tributaries of the once mighty Colorado – is low yet again. And climate models say the entire region is going to get hotter and drier. More arid, less livable. The lakes reside in picturesque red rock country, but now sit surrounded by what looks like bleached bathtub rings as they evaporate in triple-digit summertime temperatures.
But the vicious feedback loop doesn’t end there: the combination of heat and drought is working to send this heat wave into truly extreme territory. With very little moisture in soils right now, heat energy that would normally be used on evaporation — a cooling process — is instead directly heating the air and ground surface.
Jane Wilson Baldwin, a postdoctoral researcher at the Lamont-Doherty Earth Observatory at Columbia University, said that given the severe drought in the West right now, many feedbacks between the land and the atmosphere are combining to produce an unusually persistent extreme.
“When the land surface is drier, it can’t cool itself through evaporation which makes the surface even hotter, which strengthens the blocking high further,” she said in an interview.
The situation is greatly amplified by increasing background temperatures due to the burning fossil fuels.
“You would be hard-pressed to come up with a metric of heat waves that isn’t getting worse under global warming,” she said, adding that the increasing intensity and duration of heat waves is particularly clear.
Heat waves are often high mortality disasters, but those deaths are preventable, she said, with advance warning, air conditioning, cooling centers, and neighbors checking on neighbors.
However, avoiding heat-related disasters also depends on the resilience of the electrical grid, which can fail if electricity demand due to air conditioning use exceeds supply. As a result, there is the double risk of infrastructure failure and health impacts from temperature extremes, as occurred during the Texas Freeze of February.