July heat waves in U.S., Europe ‘virtually impossible’ without climate change: experts – National
A new study finds traces of climate change everywhere in the devastating heatwaves that have ravaged the planet this month. Researchers say the deadly heatwaves in the American Southwest and southern Europe could not have happened without the accumulation of greenhouse gases in the air.
Such unusually intense heat waves are becoming more common, according to a study Tuesday. The same study found that heatwaves in China are 50 times more likely, occurring roughly every five years, due to increased heat trapping gases, primarily from the burning of coal, oil and natural gas.
The study also found that the stagnant atmosphere, warmed by carbon dioxide and other gases, made the European heatwave 4.5 degrees Fahrenheit (2.5 degrees Celsius) hotter, the United States and Mexico 3.6 degrees Fahrenheit (2 degrees Celsius) hotter, and the Chinese heatwave 1.8 degrees Fahrenheit (1 degree Celsius) hotter.
Using tree rings and other temperature record surrogates, climate scientists say this month’s heat is probably the hottest on Earth in about 120,000 years, and arguably the hottest in human civilization.
“Had it not been for climate change, very few of these events would have happened,” said study lead author Maryam Zakaria, a climate scientist at Imperial College in London. She said heat waves in Europe and North America would be “virtually impossible” without an increase in heat since the mid-1800s. Statistically, what happened in China could have happened without global warming.
Global temperatures have risen 2.2 degrees Fahrenheit (1.2 degrees Celsius) since the advent of industrial-scale combustion, so “combustion is not uncommon in today’s climate, and the impacts of climate change are absolutely overwhelming,” says Friederike Otto, an Imperial College climate scientist who leads a team of volunteer international scientists from World Weather Attribution conducting these studies.
The particularly intense heatwaves currently raging in Texas, California, Arizona, New Mexico, Nevada, Baja California, Sonora, Chihuahua and Coahuila are likely to occur about once every 15 years in the current climate, the study said.
But even at this level the climate is not stable. Otto said a few tens of minutes more would make this month’s heat even more common. Phoenix has had record-breaking temperatures above 110 degrees Fahrenheit (43.3 degrees Celsius) for 25 straight days and nighttime temperatures never dipped below 90 degrees Fahrenheit (32.2 degrees Celsius) for more than a week.
Spain, Italy, Greece and some states in the Balkans are likely to see heat again every decade in the current climate, according to the study.
Meteorological attribution researchers began analyzing the three simultaneous heatwaves on July 17, so the results have yet to undergo peer review, the gold standard of science. But it uses scientifically valid techniques, the team’s research is published regularly, and several outside experts told The Associated Press that it makes sense.
Study co-author Izidin Pinto, a climate scientist at the Royal Netherlands Meteorological Institute, said the way scientists do this quick analysis is to compare current weather observations in the three regions with repeated computer simulations of “a world that might not have had climate change.”
In Europe and North America, the study does not claim that man-made climate change is the sole cause of heatwaves, but it is likely that climate change is a necessary factor, as natural causes and random chance alone cannot cause this.
Texas climatologist John Nielsen Gammon said the study was reasonable, but covered a large area of the southwestern United States, so it may not apply to every location in the region.
“This summer should be seen as a serious wake-up call, as it’s clear that the entire South is facing the worst of ever-increasing heat,” said Jonathan Overpeck, dean of the University of Michigan School of Environmental Studies.
“The most important thing about heatwaves is that they kill people, especially the lives and livelihoods of the most vulnerable, killing, damaging and destroying,” Otto said.
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