Heat waves and heat risk: Phoenix and Las Vegas are experiencing the kinds of risks scientists have been warning about as greenhouse gas emissions fuel climate change.

By Phil McKenna, Inside Climate News, 23 June 2017

Large parts of the U.S. Southwest have been feeling like Death Valley this week as a heat wave has boosted temperatures to 120 degrees and beyond. Credit: David McNew/AFP/Getty Images

The extreme heat baking the Southwestern U.S. isn’t finished yet. The National Weather Service issued an excessive heat warning today for parts of Southern California and Arizona, including Phoenix, through Monday, saying temperatures are forecast to reach 108-118 degrees each day.

In its alert, the weather service warned of “a major increase in the potential for heat-related illness and even death.”

The week has provided a preview of the risks scientists warn are ahead as greenhouse gas emissions continue to raise global temperatures.

Thermometers in the Phoenix area edged up to around 120 degrees for three straight days this week, flights were grounded as the rising temperatures decreased the air density, and the city’s main burn treatment center saw twice its usual number of patients with burns caused by walking barefoot on hot pavement or getting into cars that had been heating up in the sun. Several heat-related deaths were reported in the Las Vegas area and in California.

In California, where San Diego County set a record at 124 degrees, some communities faced power outages as air conditioners ran non-stop. Arizona utility APS set a record for power demand, and said it would have been even higher without the recent increase in rooftop solar, which has added more midday power for homes and businesses.

“Heat waves like the one we are seeing in the Southwest are becoming much more frequent,” said Robert E. Kopp, director of the Coastal Climate Risk and Resilience Initiative at Rutgers University. “Looking forward, we expect the amount of extreme heat on the planet to continue increasing even more.”

Risks to Infrastucture

Since 2000, the world has seen 16 of the 17 hottest years on record.

As the Southwest has experienced this week, rising heat is a risk to human lives and to economies and infrastructure, as well.

“I think we are seeing with the airplanes, for instance, our systems, many of them are built to historical standards, not to standards of the changing climate we live in,” Kopp said. “As we push the climate out of the historical realm and into this new realm, we are starting to see some systems break down.”

“I think that calls for a major rethink of the systems we rely upon to make sure they stand up to not just in the climate of the past but the climate of the future and also obviously to try to get ourselves into a world that is not quite as extreme as it could be,” he said.

Cities are starting to take heat risks and the other impacts of climate change into consideration as they plan new construction. New York City released guidelines this spring to help architects and engineers plan future infrastructure to withstand rising seas, more powerful storms and rising temperatures.

The city expects temperatures to be 4 to 6 degrees higher in New York by the 2050s, adding to heat stress in old buildings with only window air conditioners or no cooling at all. The guidelines encourage architects to design shades over windows, angle buildings to avoid direct sunlight, and use materials and designs that will keep buildings cooler. They also encourage builders to consider power backup systems and air conditioning systems designed for higher temperatures.

Risks to Lives

According to the National Academy of Sciences, the hottest days are now hotter. Since 1950, the number of heat waves has increased across the globe, lasted longer, and covered a wider area. The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report noted that “most global land areas analyzed have experienced significant warming of both maximum and minimum temperature extremes since about 1950” and concluded that it is “likely that human influence has more than doubled the probability of occurrence of heat waves in some locations.”

The EPA cited a rising risk of deadly heat waves when it issued its endangerment finding in 2009, the determination that greenhouse gas emissions are a danger to human health and ecosystems.

At that point, the planet had already seen the 2003 European heat wave, blamed for more than 30,000 deaths across the continent, and the three-day 1995 Chicago heat wave that killed more than 700 people.

A study released earlier this week estimates that deadly heat waves will become more common across much of the planet. Today, about 30 percent of the world’s population is exposed to life-threatening heat waves for at least 20 days a year. By the end of the century, if nothing is done to reduce greenhouse gas emissions, that risk will spread to about 74 percent of all people, the study found.

new mapping analysis from Climate Impact Lab zooms in for a closer look at how average summer temperatures are expected to rise this century as greenhouse gas concentrations in the atmosphere continue to increase.

With moderate greenhouse gas emissions, along the lines of the Paris climate agreement, the average summer high temperature for the U.S. is expected to rise from a historical average of 74 degrees in the 1986-2005 to an average of 81 by 2100. With high emissions, the lab says we would see an average of 91 degrees in the U.S. Similar scenarios play out across the globe.

The impacts are most damaging in impoverished communities that can’t afford air conditioning and have less reliable power. A heat wave that swept across Asia, the Middle East and parts of Europe in late May and early June this year left parts of Pakistan sweltering in 128 degree temperatures, among the highest recorded temperatures worldwide for May.

Phil McKenna is a Boston-based reporter for InsideClimate News. Before joining ICN in 2016, he was a freelance writer covering energy and the environment for publications including The New York Times, Smithsonian, Audubon and WIRED. Uprising, a story he wrote about gas leaks under U.S. cities, won the AAAS Kavli Science Journalism Award and the 2014 NASW Science in Society Award. Phil has a master’s degree in science writing from the Massachusetts Institute of Technology and was an Environmental Journalism Fellow at Middlebury College.

High temperatures and heavy rainfall lead to widespread algae growth in Lake Erie in 2014 and 2015. A new study looks at the risks to deep lakes in higher latitudes as global temperatures rise. Credit: NASA

When rising temperatures brewed up a perfect storm of excessive rainfall and extreme heat in the summer of 2014, the fallout hit home. The impacts were felt by at least half a million people in Ohio when a super-bloom of cyanobacteria, a toxic blue-green algae, shut down drinking water supplies for several days.

The algae feasted on fertilizers washed in from farm fields, and the warming may have pushed the lake past an environmental tipping point. In warming waters, the cyanobacteria thrived and spread in a slimy green froth across hundreds of square miles. Schools, restaurants and other public facilities shut down after contamination was detected in Toledo’s water intake system, and local stores quickly ran out of bottled water. In the summer of 2015, the algae spread again.

Similar blooms in Lake Erie were common in the 1960s through the 1980s and then diminished, thanks to better pollution controls. But the outbreaks have increased once again in the past decade, according to NOAA.

Scientists already know that the rapid warming of lakes will increase the number and intensity of such blooms, as well as other disturbances like oxygen-deprived dead zones. A new study published June 23 in the journal Scientific Reports helps identify which lakes are most likely to be affected, information that can help people and communities develop adaptation plans amid climate change.

Based on an evaluation of 20 years (1991-2011) of data, the study concluded that deep lakes in cold climates—including the Great Lakes— are most at risk from global warming. As the buildup of greenhouse gases continues, some lakes have already passed climate tipping points. Many others could breach critical temperature thresholds in the next few decades.

Deep lakes are warming fast because they can store heat for a long time, which enables it to build up. By contrast, smaller, shallower lakes are also warming, but can cool down relatively quickly when temperatures drop. Lakes in cold climates are strongly affected by global warming as their ice cover melts earlier each year, allowing the sun’s heat to penetrate the water much earlier in the spring.

Lead author Iestyn Woolway, from the University of Reading, said one of the biggest concerns is how lakes will respond to extreme heat events, as well as large, stair-step changes like the sudden upturn in global temperatures that started in the 1980s. Some lakes may be able to respond to gradual changes in temperature, but research shows that big shifts have already hit lakes hard, he said.

“The rapid temperature increase observed in lakes over the past 100 years could cause widespread damage to the ecosystem,” Woolway said. “In terms of temperature thresholds that could ‘tip’ an ecosystem, the most likely to have significant impact would be 4 degrees Celsius.”

When lake surface temperatures increase by more than that early in the spring, it disrupts the natural cycling, or upwelling, of deep, cold water to the surface. That persistent layering leads to oxygen-starved in the depths. Such dead zones are set to increase by 25 percent through the end of the century.

Illinois State University researcher Catherine O’Reilly said there’s no doubt that climate change will shift lakes into new regimes. “These tipping points or thresholds are likely created not just by climate change itself, but by interactions between climate change and other factors, such as climate oscillations like El Niño … But now, each year is a new record-setting year, and because the climate itself does not return to normal, the lake is never able to recover completely,” she said.

Knowing which lakes are likely to be affected and when it will happen will help communities prepare for the impacts, said Rensselaer Polytechnic Institute researcher Kevin Rose. Beyond cutting global greenhouse gas emissions and limiting warming, scientists emphasize that maintaining healthy ecosystems are the best way to make them resilient to climate change and other impacts. For fish and other freshwater organisms, the key to survival may be mobility.

“If there are fewer barriers to dispersal among lakes, like, dams, and road culverts, then fish and other species can move among water bodies to find better habitat. Removing barriers might help species maintain their preferred temperature ranges,” he said.

Most mitigation measures would be based on site-specific conditions, Woolway said. Increasing monitoring would help detect temperature shifts in real-time to track the potential for any ecological disturbances.

“Creating climate sanctuaries would certainly help some threatened species and limit the impact of non-native species from dominating a system,” he concluded.