Report on the observed climate, projected climate, and projected biodiversity changes for Yosemite National Park under differing levels of warming

Yosemite National Park is among the top 24% of all non-marine protected areas, globally. As a park with mixed topography, higher elevation areas are projected to be more resilient than lower elevation areas (including Yosemite Valley). Averaged over the entire area, with 4°C warming (global, above pre-industrial), the area is projected to remain climatically suitable for 66.5% of its terrestrial biodiversity (fungi, plants, invertebrates, and vertebrates), with 33.9% of its area remaining an overall refugia (remaining climatically suitable for >75% of the species) for biodiversity. However, if warming levels were held to 2°C, 77.1% of the area would remain a climatic refugia and the area would remain climatically suitable for 84.4% of its terrestrial biodiversity.
Between 1961-1990 and 1991-2020 the average monthly temperature has increased by 0.4°-1.2°C. With warming levels of 2.0°C the new average monthly temperature is equivalent to that only seen 1 in 3 years in 1961-1990 for all but three months. April stays about the same, but July and August have a projected average temperature the same as experienced in 1 in 20 years between 1961-1990. Seven months have seen declines in precipitation with the rest seeing increases. There appears to be a seasonal shift with drier summers and autumns but wetter winters. The number of months with severe drought has increased between 1961-1990 and 1986-2015. With 2°C warming (global, relative to pre-industrial) the number of consecutive months in severe drought more than doubles with the possibility of droughts exceeding two years in duration.
Biodiversity adaptation options would include business as usual adaptation at higher elevations, taking into account changes in extreme events (especially severe drought). Areas at lower elevations, including Yosemite Valley, would need increasing levels of adaptation effort even at lower levels of warming.