Four Corners Drought Intensified By Human-Induced Warming

The Four Corners drought of 2017 and 2018 caused $3 billion in losses and led the Navajo Nation to issue an emergency drought declaration.

Now, new research in the Bulletin of the American Meteorological Society suggests a sizable portion of the drought’s impacts stemmed from human-induced climate change.

“We’re going to keep seeing temperature rise, meaning we’re going to keep seeing these extreme events, these impacts occurring, and that makes it really important to start thinking about adaptation,” said co-author Emily Williams, a doctoral student at University of California, Santa Barbara.

In addition to UC Santa Barbara colleagues Chris Funk and Shraddhanand Shukla, Daniel McEvoy of the Western Regional Climate Center in Reno, Nevada, contributed to the research.

The Four Corners drought was intensified by the hottest regional temperatures on record, and occurred during a severe meteorological drought.

Unusually high temperatures worsen droughts in the Southwest by reducing snowpack and causing snow to melt earlier, depriving affected areas of seasonal river flows.

They also increase the amount of water the atmosphere can hold, making air “thirstier” and causing it to pull moisture from plants and soil.

According to model simulations, human-induced warming added 2.3 to 3.6 degrees Fahrenheit (1.3 to 2.0 C) to that heat—parching soil and shrinking plant coverage by 18–30 percent and making poor rangeland conditions worse.
It also drained away 20 percent of potential snowpack meltwater.

Williams said events like these reveal climate change already at work.

“And this drought, which hurt so much of the interior of the U.S., is one of those examples of what climate change looks like in the here and now,” she said.

As available water is exhausted, an additional feedback between land and water can occur: As evaporation, which absorbs latent heat and cools the area, becomes impossible, sensible heat can climb even higher.

“If this is happening in a really dry environment and there’s no more moisture in the soil that will then lead to even greater temperature rise,” said Williams.

Because the study did not model such effects, its results likely reflect a conservative estimate of the impacts of human-induced warming.

Navajo, SRP Take Steps To Make Solar A Priority

The Navajo Nation is taking steps to make solar energy a priority, with the help of Salt River Project.

Salt River Project seeks proposals for up to 200 megawatts of solar development on the Navajo Nation. That energy will be transmitted to SRP customers in the Valley.

Proposed projects must be in operation by December 2023, so they can take advantage of federal tax incentives.

The contract will help SRP reach its goal of 1,000 megawatts of new solar energy in the next five years. The utility has committed to reducing carbon dioxide emissions by 90% by 2050.

“It’s the beginning of a new era for the Navajo Nation,” Navajo President Jonathan Nez said. “We recognize that coal-based energy provided many benefits for the workers and their families, but times are changing and energy development is changing.”

In November, SRP and other utilities shut down the Navajo Generating Station, a coal-fired power plant, in favor of natural gas and renewable energy.

“We are looking to become the leader in renewable energy throughout the Southwest and Indian Country,” Nez said.

Study: Droughts are growing hotter under climate change

Arizona is in its 21st year of drought, and climate change is bringing longer, more intense heat waves. Now, scientists at University of California, Irvine, have found that many areas experiencing dry conditions are heating up faster than the rest of the country.

The study was published in the journal Science Advances.

Anyone with a swamp cooler or mister knows that evaporating water cools the air. Changing water from liquid to vapor takes energy, and heat is lost from the air as energy is absorbed. Conversely, dry areas really feel the heat. Take, for example, research regarding the southwestern U.S.:

“We’ve observed a shift of approximately 0.6 degrees Celsius (1.0 Fahrenheit) between the first and the second half of the 20th century. But if you only include months classified as dry, you see that there’s almost double the shift in temperature,” said lead author Felicia Chiang, a graduate student researcher in civil and environmental engineering at UC Irvine.

“If you only include months classified as dry, you see that there’s almost double the shift in temperature.”

Combining observations from the early and late 20th century with model results from the late 20th and late 21st century, the team expanded its research to incorporate the entire U.S.

Both observational data and climate models showed the same pattern in the southern U.S.: greater temperature shifts under dry conditions than under average climate change conditions, whether in arid Arizona or rainy Louisiana (both are included in what the study considers “southern states”).

“We believe that they’re likely shaped by concurrent changes in the moisture in the atmosphere,” Chiang said.

The combination of stressors will likely comprise the environmental and social impacts of drought and heatwaves, driving more frequent wildfires, worsening air quality and stressing crops and livestock.

The findings also underline the potential impacts of land-use changes, and their effects on local moisture availability.

The authors recommend that societies and their institutions study these effects and work to improve the resiliency of affected systems.