Inter Mountain Basins Big Sagebrush Shrubland

Climate exposure is a measure of the degree of climate change a species, landscape, or vegetation type has already experienced or is projected to experience. We analyzed current climate change exposure on western vegetation types between a 20th century baseline (1948-1980) and a recent time-period (1981-2014). To do this we measure change in temperature and precipitation relative to baseline climatic variability across time (year-to-year variability) and across space (variation across geography). More specifically these include:


1) Typicality: This analysis quantifies change relative to variability across time for a fixed location in geographic space. This results in a map depicting departure from historical climate norms across the distribution of the type. Each pixel is a measure of how typical current climate values at that location are compared to baseline climate values. The scale ranges from 1, which indicates that climate in the recent is not departing from the range of values observed during the baseline, to 0, which means the climate of the recent is completely novel from the conditions that occurred in the baseline.


2) Change in Climate Suitability: This analysis quantifies change relative to variability across geographic space. We use bioclimatic niche modeling to quantify change relative to the variability of climate across the vegetation type’s historical geographic distribution. This results in a map of where predicted climate suitability may be declining or improving. Values range from -1 (declining climate suitability) to 1 (improving climate suitability).


Both exposure metrics are combined to produce an overall exposure layer that is used as input into the Habitat Climate Change Vulnerability Index (HCCVI). See layer descriptions for more detailed explanation of methods for each exposure layer.