So More than ever before, climate researchers from seven nations have identified human-accelerated global warming as the cause of an extreme weather event: the Siberian heat wave in this early summer would “most likely” not have been possible without climate change. Even if the warming that had been measurable in the Arctic for years was part of a natural process, the tropical peak temperatures that persisted in May and June could only have occurred once every 130 years. Climate change has increased the likelihood of this unusual warming period six hundred times between January and June, writes the World Weather Attribution Initiative (WWA) in its analysis presented a few days ago.

Joachim Müller-Jung

Editor in the feature section, responsible for the “Nature and Science” department.

The high point of the long-lasting heat wave was a record value of 38 degrees Celsius at the Verkhoyansk weather station beyond the Arctic Circle, which had not yet been confirmed by the WMO. The result was an above-average number of forest fires. Overall, the temperature values ​​used in the study in the large Siberian strip between 60 and 75 degrees north and 60 to 180 degrees east were five degrees above the long-term average of the first six months. The research team, in which, in addition to climate analyst Friederike Otto, who worked at Oxford University, Russian scientists and experts from the German Weather Service were also involved, evaluated the temperature history of the available measuring stations using statistical methods and at the same time systematically compared them with the values ​​determined in climate models.

The map obtained on June 19, 2020 by the ECMWF Copernicus Climate Change Service shows the surface temperature in eastern Siberia.

The result was that without the strong warming of the atmosphere driven by greenhouse gases such as carbon dioxide, values ​​like in the first half of the year can hardly be simulated.

A heating up of 2.5 to seven degrees can be expected

Extreme heat like that of 2020 would have been at least two degrees Celsius colder around 1900. Such extreme heat would have been possible only every 80,000 years without the rise in man-made greenhouse gases. As far as the future is concerned, the models point to further above-average warming in Siberia and thus to a growing danger of melting permafrost soils that have been frozen all year round within the Arctic – which at some point should further intensify the greenhouse effect due to large-scale outgassing of methane. Researchers are still unsure how quickly this will happen. According to the WWA scientists, however, a heating up of the greater region of 2.5 to 7 degrees Celsius can be expected by 2050.

The study confirms once again that the Arctic and the far north are currently warming up about two to three times as much as the rest of the world. The WWA consortium, co-founded by Friederike Otto, has so far carried out 350 analyzes of extreme weather events in recent times and identified the bushfires in Australia and the previous heat wave in France as likely results of climate change.

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