The Arctic is no longer changing slowly.
According to a new international study, the region has entered a new phase marked by frequent and intense extreme weather events—conditions that many Arctic ecosystems have never experienced before.
The research was led by scientists from the Finnish Meteorological Institute, with collaborators from institutions including the University of Sheffield and the University of Helsinki.
By analyzing more than 70 years of climate data, the team carried out the first large-scale study focused on long-term changes in the Arctic’s “bioclimate”—the climate conditions that directly affect living organisms.
While rising average temperatures in the Arctic are well known, the researchers found that extreme events are increasing even faster.
These include prolonged summer heatwaves, sudden frosts during the growing season, and unusually warm winter periods. In many parts of the Arctic, some of these extremes have appeared only within the last 30 years.
One particularly worrying example is the rise of “rain-on-snow” events. These occur when rain falls on existing snow cover during winter.
The rain then freezes, forming hard ice layers within the snowpack. For animals such as reindeer, this can be devastating.
The ice prevents them from reaching the lichens they rely on for food, leading to starvation and population declines. The study found that rain-on-snow events now affect new regions covering more than 10% of the Arctic’s land area.
The researchers also identified several Arctic “hotspots” where changes have been especially intense.
These include Western Scandinavia, parts of Central Siberia, and the Canadian Arctic Archipelago. In these regions, both seasonal climate patterns and extreme events are shifting rapidly, placing plants, animals, and human communities under growing stress.
Juha Aalto from the Finnish Meteorological Institute explained that Arctic ecosystems are closely tied to seasonal rhythms such as snow cover and growing seasons. Until now, however, scientists had not examined extreme bioclimatic events across the entire Arctic in a comprehensive way.
Gareth Phoenix from the University of Sheffield said the findings show a clear turning point. Across roughly one-third of the Arctic, extreme weather events are appearing for the first time in recorded history.
These conditions can kill plants across large areas, increase animal deaths, and threaten the livelihoods of Indigenous peoples, including reindeer herders.
The impacts are not limited to the Arctic. Damage to Arctic ecosystems may reduce the region’s ability to store carbon, which could accelerate global climate change and affect people far beyond the polar regions.
Miska Luoto from the University of Helsinki noted that Arctic ecosystems are now being exposed to climate conditions they are not adapted to survive. The long-term consequences, he said, could be profound and irreversible.
To conduct the study, the team used advanced atmospheric “reanalysis” data, which combines weather observations with climate models. This approach is especially important in remote regions like the Arctic, where direct measurements are limited.
The researchers emphasize that accurate, up-to-date climate information is essential for tracking Arctic biodiversity, predicting future risks, and helping societies adapt.
Their conclusion is clear: the Arctic has entered a new and unfamiliar climate reality, and the effects are already unfolding.
Source: University of Sheffield.
