The findings show that even regions traditionally seen as immune to extreme heat are now experiencing rapid and dangerous warming. On 15 May, Iceland's Egilsstaðir Airport recorded a historic 26.6°C — the country's hottest May temperature. Just days later, eastern Greenland saw 14.3°C, far above its usual May average of 0.8°C.
"To some, 3°C might not sound like much, but it triggered significant ice loss in Greenland," said Dr Sarah Kew, one of the study's 18 contributing scientists. In fact, preliminary data from the U.S. National Snow and Ice Data Center suggest that ice melt during this period was 17 times higher than the seasonal norm.
A warming Arctic creates new risks
"The Arctic is warming more than twice as fast as the global average," said Maja Vahlberg of the Red Cross Red Crescent Climate Centre. Communities in Iceland and Greenland—long adapted to stable, cold weather—are now facing rising threats to public health, infrastructure, and traditional ways of life.
Sunburn alerts and melting roads in Iceland are just some of the new challenges. In Greenland, thinning sea ice is isolating Indigenous Inuit communities from hunting grounds and transportation routes. The decline in sea ice has also led to a dramatic reduction in sled dog populations—an integral part of Inuit culture for generations.
‘This isn't just one extreme event'
Dr Halldór Björnsson of the Icelandic Met Office says May's heatwave shattered century-old records, with 94% of Icelandic weather stations reporting unprecedented temperatures. "The old statistics no longer apply," he said. "We are witnessing a change in the climate baseline."
The WWA researchers estimate that, if emissions continue on their current trajectory and global temperatures rise by 2.6°C by 2100, future Icelandic heatwaves could become up to 2°C hotter than today. In Greenland, the warmest May day was already 3.9°C hotter than it would have been in a pre-industrial climate.
Global consequences
"What happens in the Arctic doesn't stay in the Arctic," warned Dr Friederike Otto of Imperial College London. The heat-induced melt accelerates sea level rise, threatening low-lying island nations such as Tuvalu and Kiribati, and weakening global ocean currents.
One of the most critical risks is to the Atlantic Meridional Overturning Circulation (AMOC), a major ocean current system. Continued melting of the Greenland ice sheet could destabilise AMOC, potentially leading to dramatic shifts in weather systems and plunging parts of Europe into a deep freeze.
The solution is clear — and urgent
Greenland currently loses an average of 43 billion tonnes of ice annually. A growing body of evidence suggests that exceeding 1.5°C of warming could trigger irreversible loss of ice from both Greenland and Antarctica, causing several metres of sea level rise over time.
"We know exactly what's causing this," said Dr Otto. "Fossil fuels are driving the warming, and we have the technology to transition away from them. What we lack is the political will to treat this as a universal human rights issue—not just one for the wealthy and powerful."