Climate change made the recent "relentless" heatwave in Norway, Sweden and Finland about 2C hotter and at least 10 times more likely, according to scientists from the World Weather Attribution network. The two weeks of unusually hot weather from mid-July, with temperatures above 30C, would be "extremely rare" without human-caused global warming.
The extreme weather hit during peak Nordic holiday season and triggered devastating consequences across the region. Heat-related deaths, overcrowded hospitals, increased drownings, wildfires, and algal blooms on coastlines all resulted from the unprecedented temperatures, with reindeer even straying into towns seeking shade and water.
Finland experienced a record-breaking 22 consecutive days above 30C during the period. Researchers found that in a world without climate change, such a two-week period of extreme heat would be extremely rare, but now occurs roughly every 50 years with current warming levels.
Current climate impact
With 1.3C of warming caused by humans burning fossil fuels, the Nordic heatwave became at least 10 times more likely than in pre-industrial conditions. The rapid attribution study also found climate change made the event about 2C hotter than it would have been naturally.
Scientists warn that even small increases in warming expose people to dramatically more frequent dangerous heat events. The 0.2C in global warming since a similar heatwave in 2018 has made such events twice as likely.
Future projections
If warming reaches 2.6C above pre-industrial levels by 2100 as projected, Nordic heatwaves will become five times more likely than today. They would also be another 1.4C hotter than current levels without rapid action to halt fossil fuel use.
Dr Clair Barnes from Imperial College London said: "This heatwave was relentless.
"Two weeks of temperatures above 30C in this region is unusual and of course, highly concerning.
"Climate change is fundamentally reshaping the world we live in.
"Cold-climate countries like Norway, Sweden and Finland are now experiencing unfamiliar levels of heat, as recently seen in strained health systems and sightings of reindeer seeking shade in urban areas.
"We found that the likelihood of a prolonged period of heat like this has almost doubled since 2018, when the region last experienced such an intense heatwave - and this trend is going to continue if we don't stop filling the atmosphere with planet-heating gasses.
"A rapid transition from fossil fuels to renewable energy is the only way to slow and, hopefully, ultimately stop this warming."
Global context
The Nordic findings emerge as southern Europe faces record scorching temperatures soaring past 40C and causing widespread wildfires. Parts of the UK are under an "amber heat health alert" in the fourth heatwave of the summer as temperatures climb into the 30s.
Prof Friederike Otto from Imperial College London warned: "Even comparably cold Scandinavian countries are facing dangerous heatwaves today with 1.3C of warming.
"This event should be taken as another reminder that no country is safe from climate change." She pointed to recent extreme heat in the US, Japan and South Korea, and wildfires in France and Turkey, saying "burning oil, gas and coal is killing people today."
UK experts also warn that homes, hospitals, workplaces and schools are not prepared for increasingly dangerous heat impacts.
Sources used: "World Weather Attribution network", "Imperial College London" Note: This article has been edited with the help of Artificial Intelligence.
