In a brand new result, a study shows that six months in a row unusually mild conditions in much of northern Siberia this year, along with an Arctic temperature record of 100.4 degrees (38 degrees Celsius) in June, would have been practically impossible without the man-made ones global warming.
The study, released on Wednesday by the World Weather Attribution project, was developed in collaboration with climate researchers from several institutions in France, Germany, the Netherlands, Russia, Switzerland and the United Kingdom.
The researchers found that the persistent heat from January to June, which has led to record-breaking forest fires in the Siberian Arctic, was at least 600 times more likely to be caused by man-made climate change. This led them to conclude that such an event would be almost impossible without global warming.
The analysis shows that the six months with far above-average temperatures in the region would occur less than once in 80,000 years without man-made climate change.
Scientists used an increasingly established technique known as climate detection and attribution that corresponds to climate change detective work to determine whether and by how much global warming affects the likelihood of an extreme climate or weather event.
In this case, the researchers used statistical methods and dozens of computer models to study above-average temperatures for six months, which were observed in large parts of Siberia from January to June, as well as the provisional Arctic temperature record of 100.4 degrees (38 degrees Celsius). that happened on June 20 in Verkhoyansk north of the Arctic Circle.
Even in the current climate, the study finds the six months of unusually mild conditions, with the event likely to occur less than once every 130 years.
The study found that for the large region examined, temperatures would have been at least 3.6 degrees (2 degrees Celsius) cooler in the past six months if the same weather pattern had occurred in the period from January to June 1900 compared to 2020.
And in Verkhoyansk, the maximum temperatures in June rose by at least 1.8 degrees (1 degree Celsius) compared to 1900.
Previous studies in this group have consistently shown that climate change makes heat waves more likely and more intense than without human-made global warming. But they have never drawn such strong conclusions.
For example, a study of a European heat wave last year found that global warming is likely to increase the likelihood of the extreme event fivefold. However, the new study found that the heat streak in Siberia from January to June could occur in the absence of global warming less than about every 80,000 years.
“After what we’ve done, it’s the strongest signal we’ve seen,” said Friedericke Otto, Acting Director of the Oxford Environmental Change Institute and co-leader of the World Weather Attribution initiative, during a conference call with reporters.
Temperatures in Siberia over the past six months would “have been practically impossible without human influence,” said Andrew Ciavarella, lead author of the research and lead scientist for detection and attribution at the UK Met Office.
Ciavarella said there is greater uncertainty about how much global warming has increased the likelihood of record temperatures in Verkhoyansk, but that the hottest June temperatures in this location have increased by 1.8 to 3.6 degrees (1 to 2 degrees Celsius) ), which is what makes the Arctic record temperature much more likely today.
“In nature, this event would have been almost impossible,” he said.
The new research is not the first to conclude that an extreme event would have been practically impossible without man-made climate change. Another study of a fatal heat wave in Japan in 2018 and a study published last year on a flood of extreme heat in the northern hemisphere.
In order to reach the conclusions of the study, the researchers carried out around 70 computer models with thousands of simulated years to record the development of the climate with and without the addition of greenhouse gases to the atmosphere. They also examined observation reports in the broad region and in Verkhoyansk.
The study found that temperatures in the region warmed about three times faster than in the rest of the world, and a warming between 0.9 and 9 degrees (0.5 to 5 degrees Celsius) is expected in 2050.
While the study itself was conducted as a quick analysis without peer review, the methods used by the scientists were based on peer review studies, and the authors said that they are likely to submit the work to an academic journal.
Michael Wehner, a senior scientist at the Lawrence Berkeley National Laboratory who was not involved in the new study, said the methods used by the researchers were “state of the art”. He described the results as conservative.
“This is a very careful and comprehensive study done by the best in the field using established methods,” said Wehner via email. “Your finding of a very large human impact on this event is actually quite conservative. I am sure that this heat event was made worse by human intervention in the climate system. “
Katharine Hayhoe, a climate researcher at Texas Tech who was not involved in the new study, said that many attribution studies find that human exposure to certain extreme events is relatively small, but this is not the case.
“In this case, the answer is really unprecedented. We are witnessing events today that, as the authors say, would be almost impossible without man-made climate change, ”she said in an email.
“The reality is that we humans are doing an unprecedented experiment on the only planet we have. It has been unprecedented in the amount of carbon that we pump into the atmosphere each year, and now it is unprecedented in the impact we experience as human beings. “
Siberian heat influences are widespread and persistent
The persistent, unusually mild temperatures in Siberia have a significant impact on ecosystems, human settlements and even the climate itself. Arctic forest fires started unusually early this year due to the hot, dry conditions in Siberia, with particularly violent flames occurring in the Russian Republic of Sacha . Such fires contribute to global warming by emitting carbon dioxide and soot. They can also destabilize permafrost and release old stocks of carbon dioxide and methane.
Arctic infrastructure is also threatened by warming temperatures, as shown by the damaging oil spill in Norilsk that authorities have attributed to melting permafrost. While Siberia is not densely populated, heat waves are among the deadliest weather events in much of the world. They can worsen existing conditions and affect people both mentally and physically.
“As emissions continue to rise, we have to think about increasing extreme heat resistance around the world, even in arctic communities – which would have seemed nonsensical not long ago,” Otto said in a statement.