The warming climate is transforming moth communities across Finland. According to researchers at the University of Helsinki, northern cold-adapted species are becoming rarer while southern Finland is seeing an influx of warm-adapted species from the mainland Europe.
A new study published in Nature Communications, led by the University of Helsinki examined how climate change is altering moth communities across Finland. The researchers wanted to understand whether communities are undergoing thermophilisation – a shift towards species that prefer warmer conditions – as the climate warms.
Their findings confirm that Finnish moth communities are becoming increasingly dominated by warm-adapted species. While the thermophilisation was observed across the country, the mechanisms that lead to it were strikingly different.
In northern Finland, thermophilisation was occurring at a faster rate and primarily driven by the local disappearance of cold-adapted species. In contrast , southern Finland experienced thermophilisation through the arrival of new warm-adapted species, while most resident species persisted.
These findings suggest that cold-adapted species in northern Finland are particularly vulnerable under climate change, as the communities face more species losses than additions. This pattern points to a greater risk for communities at the cold edge of species' climatic ranges.
“The rate of change in the composition of moth communities was twice as fast in the north compared to the south,” says lead author Dr. Emilie Ellis from the Research Centre for Ecological Change . “That rapid pace makes northern biodiversity especially vulnerable to the harmful effects of climate warming.”
Recognising that cold-adapted species are at risk will help to inform conservation strategies to support Finnish biodiversity. According to researchers continued monitoring and research are therefore crucial to track how these species are changing over time.
The team drew on a long-term dataset built through decades of dedicated volunteer monitoring. It includes more than 224,000 moth observations collected across Finland’s 1,200 km length over a 30-year period. This extraordinary effort made it possible to uncover how climate change is reshaping moth community composition across the country.
The research was done in collaboration with the Finnish Environment Institute.
Nature Communications
Recent community warming of moths in Finland is driven by extinction in the north and colonisation in the south
12-Aug-2025