Arctic heatwave would have been almost impossible without human-caused climate change: Climate scientists

Vibha Sharma
Tribune News Service
New Delhi, July 16 

The recent record-breaking Arctic heatwave would have been “almost impossible” without the influence of human-caused climate change, according to rapid attribution analysis by a team of leading climate scientists published on Friday.

The analysis found that the prolonged heatwave that Siberia experienced from January to June this year would only happen less than once every 80,000 years without human-induced climate change. It would otherwise be impossible in a climate that had not been warmed by greenhouse gas emissions.

Climate change increased the chances of the heatwave by a factor of at least 600. This is among the strongest results of any attribution study conducted to date and is unequivocal evidence of the influence of human-induced climate change on the planet, according to the analysts.

Impact of Arctic warming is well-established. Consider this: 38 deg C in a Siberian town is almost the same as Delhi right now.

Warming arctic means rapid glacial melt which will lead to sea-level rise impacting SSTs. Indian Ocean Dipole is a phenomenon when the western part of the ocean is warm and eastern is cold due to glacial melt, leading to climatic impact in the entire region across the Indian Ocean.

Researchers from international universities and meteorological services also found that temperatures were more than 2°C hotter than they would have been if humans had not influenced the climate by releasing greenhouse gas emissions.

Temperatures in Siberia have been well above average since the start of the year.

A new record temperature for the Arctic, 38°C, was recorded in the Russian town of Verkhoyansk on 20 June, while Siberia’s overall temperatures were more than 5°C above average from January to June.

The heat in Siberia has triggered widespread fires, with 1.15 million hectares burning in late June, associated with a release of about 56 million tonnes of carbon dioxide, more than the annual missions of some industrialised countries such as Switzerland and Norway.

It also accelerated the melting of permafrost - an oil tank built on the frozen soil collapsed in May, leading to one of the worst oil spills ever in the region. Greenhouse gases released by the fires and melting permafrost—as well as decreases in the planet’s reflectivity from loss of snow and ice—will further heat the planet. The heat has also been linked with an outbreak of silk moths, whose larvae eat conifer trees, says the analysis.

Géosciences de l’Environnement, Grenoble, lead author IPCC AR6 says: “This study shows that not only was the magnitude of the temperature extremely rare but also the weather patterns that caused it. The blocking of the weather system over the Urals that caused the prolonged period of heat is projected to intensify with climate change leading to more events like this potentially occurring. We are continuing to study how the wildfires that have burned over thousands of hectares might also affect the climate as the flames pump smoke and ash into the atmosphere.”

According to the lead author of the research and Senior Detection and Attribution scientist at the Met Office Andrew Ciavarella: “The findings of this rapid research – that climate change increased the chances of the prolonged heat in Siberia by at least 600 times – are truly staggering. 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.”

Dr Friederike Otto, acting director of Oxford’s Environmental Change Institute, and co-lead of the World Weather Attribution initiative: “This study shows again just how much of a game-changer climate change is with respect to heatwaves. Given that heatwaves are by far the deadliest extreme weather events in most parts of the world they must be taken very seriously. As emissions continue to rise we need to think about building resilience to extreme heat all over the world, even in Arctic communities – which would have seemed nonsensical not very long ago.”

Prof. Sonia Seneviratne from the Department of Environmental Systems Science at ETH Zurich (D-USYS), a lead author on several IPCC reports: “These results show that we are starting to experience extreme events which would have almost no chance of happening without a human footprint on the climate system. We have little time left to stabilize global warming at levels at which climate change would remain within the bounds of the Paris Agreement. For a stabilization at 1.5°C of global warming, which would still imply more risks of such extreme heat events, we need to reduce our CO2 emissions by at least half until 2030.”