A new era of extremes is taking hold in the Arctic

The Arctic isn’t just warming; it’s undergoing a fundamental shift in the kinds of weather events it experiences. A study published in Science Advances found that the region has moved into what researchers describe as a new era of climate extremes, with potentially serious consequences for plants, animals and the people who live there.

Led by Juha Aalto of the Finnish Meteorological Institute and carried out by an international team that included researchers from the University of Sheffield, the study is the first to take a comprehensive, long-term look at changes in the Arctic’s “bioclimate” — the climate conditions that directly affect living organisms.

By analyzing more than 70 years of data, the team found that beyond steadily rising average temperatures, Arctic ecosystems are increasingly exposed to extreme events such as prolonged heatwaves, unexpected frosts during the growing season and unusually warm winter spells. The severity and spread of these extremes differ across regions, but together they signal a broader transformation underway across the North.

Key Findings

• The Arctic is experiencing record-setting weather shifts. Scientists found that unusual heatwaves, frosts during growing seasons, warm winter spells and rain-on-snow events have become much more common, in many cases emerging only within the past 30 years.
• Rapid warming is fueling the change. The Arctic is warming several times faster than the global average, accelerating shifts in temperature, snow cover and atmospheric conditions that make extreme events more likely.
• Ecosystems are facing novel stressors. These new weather extremes expose plants, animals and soils to conditions they have not evolved to withstand, such as rain landing on snow, which can form ice layers that make it harder for wildlife like reindeer to reach food.
• Communities are feeling the effects too. Shifts in seasonality, storms, thaw cycles and freeze–thaw transitions are affecting hunting, travel, infrastructure and traditional ways of life for people across the North.
• The impact isn’t confined to the Arctic. Changes at high latitudes can influence large-scale atmospheric circulation patterns by altering temperature gradients that help drive the jet stream, which can in turn shape weather extremes in regions far beyond the Arctic, including Europe and North America.

Why it matters

“Our research shows that the frequency of extreme weather events has increased sharply in the Arctic,” said Professor Gareth Phoenix, Professor of Plant and Global Change Ecology at the University of Sheffield. “The Arctic is entering a novel era of weather extremes with likely severe consequences for ecosystems there.”

These shifts strain plant and animal life, affect food security and travel for Indigenous peoples and could alter how the Arctic absorbs carbon from the atmosphere.

A companion review published in Science Advances places these findings in a broader context, arguing that the Arctic climate system is reorganizing, not simply warming. More intense and unpredictable weather in the Arctic can stress fragile ecosystems, challenge traditional lifestyles and feed back into global weather patterns, making heatwaves, cold snaps and storms more volatile elsewhere. Understanding these changes helps scientists and communities prepare for a future in which extreme weather may become more frequent and disruptive.

“Policy-makers must recognize extremes as drivers of change,” said Torben Christensen, a professor at the Department of Ecoscience at Aarhus University. “Adaptation strategies, from infrastructure design to wildlife management, should incorporate scenarios of acute disturbance, not just gradual trends.”

As the Arctic becomes more volatile, researchers argue that sustained monitoring and a shift in how these changes are assessed are imperative for science and society alike.

Read the full research here.