Monday, July 10, 2017 | 2 a.m.
What the National Climate Assessment (2014) Predicts for the Southwest
1. Snowmelt and evaporation could reduce water supplies. Much of the Southwest’s water for farming and drinking comes from rivers that are replenished each year when snow melts off the mountains. Because of higher temperatures, streamflows are expected to decrease due to more evaporation and changes in the snowpack pattern.
2. Drought and heat could create fuel for wildfires. Climate change is expected to bring more warming, drought and insect infestations into the area. All of these factors contribute to tree deaths, which in turn creates more fuel for fires.
3. Extreme weather could hurt agricultural economies. Changes in weather patterns could affect farming yields in various regions across the Southwest. The report notes that variables such as a longer frost season and heat waves could throw off crop production.
4. Urban heat could create public health issues. Increased heat can exacerbate poor air quality, creating respiratory issues for residents. Neighborhoods without trees and with limited access to air conditioning are expected to be hit the hardest.
On June 19, the National Weather Service branch in Sacramento, Calif., tweeted a photo of bacon and cookies baking on the dashboard of a car, ending the post with “#heatwave.”
As Death Valley approached the 125-degree mark around the same time, “heat tourists” seeking extreme weather came to the national park near the Nevada border from as far away as Europe, the Associated Press reported.
Meanwhile, American Airlines canceled about 50 flights at Phoenix’s Sky Harbor International Airport, where the temperature neared 120 degrees (the Arizona Republic’s heat blog reported that American Eagle’s Bombardier CJR aircraft had a maximum operating limit of 118 degrees).
On the same week in June, Las Vegas tied its record high of 117, reached only four times in 75 years. Pets suffered burns from pavement, the surface temperature often rising 30 to 40 degrees above the air temperature. The Los Angeles Times reported that Caesars Entertainment was closely monitoring its flamingos — it reportedly doesn’t bring them out when it’s above 120 degrees. (And if the temperature had hit 110 on June 26, it would have tied the valley’s 1961 record of 10 straight days of that temperature or hotter.)
During the heat wave that swept across the region the first week of summer, utilities in some areas had to deliver more energy to customers who needed to air condition their businesses or apartments. In a handful of cases, the heat was fatal.
The West, known for hot summers, is getting a glimpse of what the future might hold if climate change continues at the current pace. Studies show that greenhouse gas emissions, which alter Earth’s thermodynamics, make heat waves not only more likely but also more severe.
“We have very clear evidence — both in terms of how the energy balance of planet Earth works and what has happened in the historical records — that continued greenhouse gas emissions are likely to cause increasing warming and further increases in extreme heat,” said Noah Diffenbaugh, who has studied the topic as a senior fellow at the Stanford Woods Institute for the Environment.
In April, Diffenbaugh authored a peer-reviewed study that found historical global warming had influenced more than 80 percent of record heat events. The report also found that the release of greenhouse gas doubled the probability of extreme heat and increased its severity.
“That’s a substantial increase,” Diffenbaugh said.
According to the U.S. National Climate Assessment, a government study produced by a team of more than 300 experts, the Southwest is expected to see temperatures rise by as much as 9.5 degrees by 2099 if heat-trapping global greenhouse gas emissions remain steady. Under an ideal scenario in which the world cut emissions, that number could be decreased by one half or more.
What that means goes beyond what you see — melting asphalt, flight delays, highway blowouts. The impact of increased heat from climate change has less detectable effects, and these indirect outcomes, some economists argue, could have significant consequences for the region’s future.
Delayed flights and a sleepy workforce.
“What we find in the data, both in the U.S. and looking globally, is that the impacts likely extend far beyond a flight getting canceled,” said Marshall Burke, an environmental economist at Stanford University. “They show up sort of indirectly in a lot of other economic measures.”
These measures include reduced cognitive performance and reduced labor activity. Burke said that research has already shown most countries see a decrease in economic growth during years that are hotter than average. A recent study out of the University of California, San Diego found that increased nighttime temperatures can interrupt sleep patterns, with implications for public health and the economy. “What’s harder to see are the effects (of warming) on labor productivity or the effects on cognition,” Burke said. “They are not immediately as observable in our day-to-day lives.”
There are a number of reasons that climate change leads to intensifying heat waves, Diffenbaugh said. But the main driver is commonly known as the “greenhouse effect.” Molecules of carbon dioxide released from power plants and methane released from agriculture, trap heat in the Earth’s climate system. As a result, more energy is reflected back to the Earth’s surface. That phenomenon, combined with other atmospheric patterns, makes heat waves more probable and severe.
Diffenbaugh says projections are variable, dependent on how much greenhouse gas is emitted in the coming years. “There are a lot of opportunities to reduce our vulnerability to severe heat when it happens and to manage how much climate change we experience in the future,” he said.