The Earth’s temperature record was broken in 2014, 2015 and again in 2016, and a new study by Penn State climate scientist Michael Mann shows that the odds of that happening without human-caused global warming are, literally, one-in-a-million.
The study, published earlier this month in Geophysical Research Letters, found that the global temperature trifecta would have been almost impossible without the heat-trapping impacts of greenhouse gas emissions from burning fossil fuels — coal, oil and natural gas.
But the probability of setting three consecutive records since 2000 was up to 50 percent higher if anthropogenic warming is part of the calculation.
“What this study shows is that the string of record-breaking years — three in a row — is extremely unlikely to have happened without accounting for human-caused warming,” said Mr. Mann ofthe Pennsylvania State University. “So when we people ask,’what is the chance occurrence of this happening,’ we can say, with confidence, that it was extremely low. In the sequence of consecutive record-breaking temperatures we see the hand of human activity.”
Byron Steinman, an assistant professor of earth and environmental sciences at the University of Minnesota, Duluth, and a co-author of the study, used poker to provide perspective to the long odds involved.
“You have a substantially better chance than one-in-a-million of drawing a Royal Flush, the best possible hand, in a five-card game of poker,” he said, Chances of drawing a Royal Flush are one in 650,000.
The recently published study is a followup to a paper published in January 2016 that found that record-setting temperatures over the past century likely would not have occurred without human-caused climate change, but the odds of that happening are not quite as low as were previously reported,
Although a scientific consensus has concluded that climate change is occurring and humans are responsible for the vast majority of global warming that has occurred since 1951, the study by Mr. Mann, Mr. Steinman and three co-authors uses historical temperature data combined with the latest climate modeling simulations to calculate the impact of human-created emissions on the record-setting temperatures of the past three years.
The peer-reviewed findings, highlighting the significance of human-made greenhouse gas emissions on climate change, contradict statements and policy positions taken by various members of the Trump administration.
Donald Trump has called climate change a Chinese hoax, and sought to withdraw the United States from the 2015 Paris climate accord signed by 195 nations. Department of Energy Secretary Rick Perry has said he doesn’t believe anthropogenic emissions are a problem. And U.S. Environmental Protection Administrator Scott Pruitt has stated that he doesn’t think carbon dioxide emissions are a primary contributor to global warming.
On Sunday, the administration decided to disband the 15-person federal advisory panel for the National Climate Assessment, a congressionally mandated review of climate data that is supposed to be issued every four years.
The committee, which included academics, local government officials and corporate representatives, was established in 1990 to help policymakers translate the scientific findings of the quadrennial National Climate Assessment. The next assessment is due in 2018 and has already become contentious for the administration.
“I think it is fair to say that that there is considerable worry among scientists.,” Mr. Mann said. “[Mr. Trump] has appointed a dream team of climate change deniers to run his administration and we have seen an agenda of disenfranchising government climate scientists, pulling out of international agreements,canceling government climate reports. It’s pretty much a worst case scenario as a far as executive action on climate change is concerned.”
A statement released by American Association for the Advancement of Science expressed concern about the “disregard for scientific advisory groups, and said it “is yet another example of the administration’s increasingly blatant attempts to ignore and dismiss scientific information.”
The planet is warming because excess greenhouse gases, including carbon dioxide and methane, from industry, power plants and vehicle emissions are accumulating in the Earth’s atmosphere along with naturally occurring gases to trap heat that would normally escape into space.
The average surface temperature of the Earth has risen 2 degrees Fahrenheit, about 1.1 degrees Celsius, since 1880 when global temperature records began. Most of the warming has occurred over the past 35 years, and, according to the National Aeronautics and Space Administration, records show 16 of the 17 warmest years on record have occurred since 2001.
Mr. Mann said that while it’s important to note, track and understand global temperature averages, it’s the extreme weather and conditions that result from those temperature increases that are most likely to impact humans and the natural world.
“Extremes can take many forms,” he said. “In this case, we’re showing that extremes as measured by successive record global temperatures, are strongly impacted by global warming. But other types of extremes—extreme weather events like heat waves, thousand-year floods, extended summer drought, are also becoming more frequent as a result of climate change.”
Don Hopey: dhopey@post-gazette.com, 412-263-1983, or on Twitter @donhopey
First Published: August 22, 2017, 9:09 p.m.
