This year’s startling heat across much of Siberia would have been all but impossible without human influence on climate change, researchers have concluded.
The scientists looked at two recent examples of exceptional heating in Siberia, one long-term and the other more brief. The first was the overall rise in temperature across the region from January to June, which was more than nine degrees Fahrenheit above average temperatures recorded between 1951 and 1980. The second was the astonishing spike on June 20 that put temperatures at the Russian town of Verkhoyansk at a reported 100.4 degrees, which the Russian Meteorological Service said is a record for temperatures anywhere north of the Arctic Circle.
In their analysis, the scientists said climate change made the prolonged heat event 600 times as likely to occur as it would be without climate change. In a statement, Andrew Ciavarella, the lead author of the research and senior detection and attribution scientist at the Met Office, the national meteorological service for Britain, called the result “truly staggering.”
For all practical purposes, said Friederike Otto, acting director of the Environmental Change Institute at the University of Oxford and an author of the paper, “you would not have gotten an event like this without climate change.”
In a world without climate change, the prolonged Siberian heat wave would only occur less than once every 80,000 years, “which is not anything you reckon with or are expecting to see in anyone’s lifetime,” Dr. Otto said. Even under current climate conditions, such prolonged warming could only be expected to recur less than once every 130 years.
The research, conducted by scientists from universities and government meteorological agencies in Germany, the Netherlands, Russia, Switzerland and Britain, employs the techniques of the emerging field of rapid attribution science, which involves computer models and rich troves of data to determine how much of a weather phenomenon may have been caused by human activities that have generated planet-warming greenhouse gases. The scientific initiative, known as World Weather Attribution, has found human fingerprints on disasters like Australia’s brush fires and the drenching rainfall from Hurricane Harvey.
The Siberia research has not yet been submitted for peer review.
The heat in Siberia has produced conditions both hellish and bizarre, with spreading wildfires, ravening mosquitoes, and destabilized permafrost that caused infrastructure damage including a burst fuel tank that released about 140,000 barrels of diesel fuel into a river. The fires have put more greenhouse gases into the Earth’s atmosphere than in any other month in 18 years of data collection, according to one report.
Zeke Hausfather, a climate scientist with The Breakthrough Institute who was not involved with the paper, said that the new research underscores the changes in the frequency of extreme weather events under climate change. “What was a one-in-100-year event a century ago, would be a one-in-20- or a one-in-10-year event now,” he said. While the Siberian heat is unusual today, if high greenhouse gas emissions persist, by the end of the century this year’s horror story could be “an average summer in Siberia,” he said.
Without climate change, the temperatures in the region during the long hot spell would have been at least 2 degrees Celsius, or 3.6 degrees Fahrenheit, cooler if it had occurred in 1900 instead of today. By 2050, the researchers said, the temperature increase in the Siberian region since 1900 could be between 4.15 and 12.6 degrees Fahrenheit.
As for the single-day June 20 spike at Verkhoyansk, the researchers noted that it is hard to quantify the influence of climate change with as much statistical confidence as the effect on long-duration heating. The high one-day temperature, the scientists said, was made many thousands of times more likely than such an event would be without climate change.
In a briefing with reporters on Tuesday about the study, Sarah F. Kew of the Royal Netherlands Meteorological Institute said that the Siberia findings are “among the strongest results of any attribution study so far.”
She added that without strong action against climate change, “we have little time to stabilize global warming” at the levels called for in the Paris climate accord, limiting the temperature rise to two degrees Celsius since the beginning of the industrial age.
In his statement, Dr. Ciavarella said, “This research is further evidence of the extreme temperatures we can expect to see more frequently around the world in a warming global climate. Importantly, an increasing frequency of these extreme heat events can be moderated by reducing greenhouse gas emissions.”