How climate change will impact vegetation is a critical question for natural resource management, and model portraying movement of species and vegetation types only partially fulfill watershed-scale management information needs, that also include estimates of where existing vegetation may be stressed and where it may remain within existing conditions. We used the mapped extents of 30 terrestrial vegetation types, to identify their current bioclimatic envelopes by the frequency with which they occupy varying climate conditions, and mapped the trajectory of each pixel’s climate under four climate scenarios to quantify areas expected to fall within, become marginal to, or go beyond their climate conditions. The four future climates represent temperature increases of 1.9-4.5°C and a +/- 25% change in annual precipitation by 2100
We present the spatial patterns of climate exposure to dominant vegetation due to climate change by the end of the 21st century based on the current emissions levels of RCP8.5 versus a reduction of emissions to the RCP4.5 target for California, USA. . Between 40 and 51% of all natural vegetation is predicted to become highly climatically stressed under current emission levels (RCP8.5) under the drier and wetter GCMs respectively, by the end of century. These areas are greatly reduced if emissions levels can be lowered to the RCP4.5 scenario, which retains temperatures below 2°C, and results in between 22% (drier) and 32% (wetter) of vegetation stressed by the end of century. These projections represent the base climate stress projected on existing vegetation, and are conservative in that they do not account for amplified drought-related mortality, fires and beetle outbreaks that have been observed during the current 4-year drought.