Plants and animals respond differently to climate change, ranging from rapid reactions to slower adaptation. Rapid reactions include, for example, behavioural changes and slower adaptation includes, for example, changes in reproduction.
Many species living in the Arctic have adapted to harsh living conditions in a way that limits their response to climate change and other environmental changes. For example, low-growing Arctic plants are easily overshadowed by higher species spreading further south, and the small-sized Arctic fox (Vulpes lagopus) does not survive the fox spreading from the south. As new species move from the south to the north, the indigenous species in the region are in difficulty. Terrestrial flora and fauna cannot move much further north because they are facing the Arctic Ocean.
The number of birds is decreasing alarmingly in the Arctic regions. A connection between so-called greening of Arctic regions and increased bird nest predation has been found in a study done in Finnmark, Northern Norway. One leading hypothesis why birds migrate to Arctic is the lower predation risk compared to southern regions
With global warming, migratory birds will arrive in their Arctic nesting grounds earlier. Spring migration - especially of first-time migrants - has also been brought forward in Lapland in recent decades. Diurnal butterflies are occurring further north in Finland: their distribution area has moved north on an average 60 kilometres in a decade. For example, the silver-washed fritillary (Argynnis paphia) used to occur mainly in south-eastern Finland, but now it occurs all the way up to Rovaniemi.
Above zero temperatures and rainfall in winter cause icy layers in the snow. They make it difficult for reindeer to feed, which increases their mortality. The number of wild reindeer and caribou (Rangifer tarandus) have fallen by 50 % in 20 years (Arctic Climate Change Update 2019).