11 key bioclimatic variables over Finland during the period 1961–2020 based on a gridded climatology. Mean values for periods 1961-1990 and 1991-2020, difference between mean_9120 and mean_6190 and significance (0/1) for the change.

Variable list : - Annual mean air temperature (°C) Average of daily mean air temperatures between 1 January and 31 December. Energy availability - species richness relationship, ranges and abundances of warm- vs. cold-adapted species3; completion of annual life cycle. - Annual precipitation sum (mm) Sum of daily precipitation levels between 1 January and 31 December.
Key factor for water-limited and water-dependent communities, joint driver with temperature to ecosystem productivity - Growing season length (days) Count of days between the onset and termination dates of the thermal growing season. Thermal growing season is defined based on a daily mean threshold temperature of 5 °C following the methodology by Ruosteenoja et al. (2016) with an additional criterion that snow depth equals to 0 cm on the onset date of the thermal growing season. Completion of life cycle and successful population regeneration, key determinant of plant growth8; multiple insect species generations within a year - Growing degree-day (GDD) sum (°C days) The cumulative sum of daily mean temperatures exceeding 5 °C during the growing season. Ranges and abundances of warm- vs. cold-adapted species, completion of life cycle and successful population regeneration. - Number of drought days Count of days when daily precipitation level has been below 1 mm for more than 10 consecutive days between 1 April and 1
October.
Increased plant drought stress and mortality, declined food and habitat resources for animals. - Water balance (mm) Precipitation minus evapotranspiration between 1 April and 30 September.
Moisture resources for vegetation and insect host and nectar plants, alteration of top-down effects on animal food webs. - Heat sum (°C days) The cumulative sum of 5-day running means of daily maximum temperatures exceeding 25 °C between 1 April and 1 October.
Increased plant drought stress and mortality, declined food and habitat resources for animals. - Number of frost days in spring Count of days with minimum temperature 0 °C and minimum temperature < 0 °C between 1 January and 30 June.
Increased frequency of biological thresholds crossing freeze - thaw cycling, energetic costs and cold injury, - Number of snow-covered days Count of days with snow depth ≥ 1 cm between 1 September and 31 August. Duration of insulating snow cover, earlier vs. delayed warm-season resource gathering. - Number of rain-on-snow days Count of days with daily mean temperature ≥ 0.5 °C, snow depth ≥ 1 cm and precipitation level ≥ 1 mm between 1 September and 30 June.
Limited resource availability to mammals and birds, energetic costs and vegetation damage.