The recent Arctic heatwave that saw temperatures rise as high as 38C in Siberia was caused by man-made climate change, scientists have warned.
Unusually high temperatures in the vast Russian region would have been at least 2C lower were it not for human-made greenhouse gas emissions, according to the research conducted by several international universities and meteorological services as part of the World Weather Attribution (WWA) initiative.
“This is one of the strongest impacts on weather we’ve ever seen from climate change,” said Dr Friederike Otto, acting director of Oxford university’s Environmental Change Institute, and co-lead author of the report.
“The silver lining is that this is still a very rare event. With today’s levels of greenhouse gas emissions, it will only happen once in a lifetime and if we manage to get to net zero gas emissions relatively soon, these events will continue to be rare.”
In May, surface temperatures in parts of Siberia were up to 10C above average, causing ice to melt and an early outbreak of large wildfires. Thawing permafrost and peatland have also released large amounts of carbon dioxide into the atmosphere.
The WWA team used computer modelling to compare today’s climate with a simulated one which had been untouched by humans, and found that prolonged hot spells like the one in Siberia would only happen once every 80,000 years if it were not for human influence. They concluded that man-made greenhouse gas emissions made the chance of a heatwave of this proportion 600 times more likely.
By 2050, the WWA researchers forecast that temperatures could increase from anywhere between 2.5C and 7C in Siberia as compared to the year 1900.
The findings come as another report raised the alarm over record global methane emissions.
Emissions of the colourless and odourless gas have risen 9 per cent to almost 600m tonnes between the early 2000s and 2017, according to a study by the Global Carbon Project, released on Wednesday.
The years 2018 and 2019 have probably seen even starker rises, providing two of the four highest annual growth rates since 2000, it also estimated.
The latest statistics on methane emissions — which derive mostly from animal farming, fossil fuel extraction and waste — suggest that the world is on track for temperature rises of 4.2C by 2100. This is the warmest scenario drawn by the Intergovernmental Panel on Climate Change, the UN body in charge of assessing climate change.
Climate policies overall have “yet to alter substantially the global emissions trajectory to date,” the report concluded.
“It’s concerning because we don’t see any stabilisation of . . . emissions, let alone a decrease,” said Marielle Saunois, assistant professor at the University of Versailles Saint Quentin and lead author on the study. “We talk a lot about CO2 emission mitigation to meet the Paris agreement but we should not forget methane in this or we could undo all of our efforts.”
Methane also derives from natural environments such as wetlands but pollutants from human activity accounted for more than half of emissions in 2017 and all of the additional methane in the atmosphere between 2000 and 2017, according to the research.
There was, however, no evidence that methane emissions have risen in the Arctic, the report said.
Existing models forecast an increase in methane emissions from the Arctic, where global average temperatures have risen twice as fast as elsewhere in the world, causing frost to melt and peatlands to thaw.