Mesoscale refugia for European alpine grasslands based on climatic envelopes

Refugia will be important to the response of alpine vegetation to climate change. Potential refugia exist at multiple scales, including a range-wide mesoscale. The climates of alpine grasslands of 23 mountain ranges of southern and central Europe were evaluated to assess whether each range would support potential refugia in projected future climates. The mean temperature the warmest month and quarter with the precipitation of the warmest quarter, derived from gridded global climate data at -1 km resolution, were examined range-wide and for areas identified as alpine grassland to identify limits within each range. The overlap of current grassland climate and future range-wide climates, the latter calculated using regional projections from three global models with three socioeconomic driving scenarios, were assessed as potential refugia. Among the nine projections, three had none of the current grassland climates in any of the 23 ranges by 2100, while two retained more than 20% in more than half of the ranges. Most of the potential mesoscale refugia were in the Alps. Micro-refugia and warmer and drier fundamental climatic niches for alpine grassland species could mitigate these bleak results, but otherwise they are extremely threatened.