From the first European explorers to modern native plant enthusiasts, California's varied and unique flora is a continual source of wonder. The California Floristic Provence is a biodiversity hotspot with over 5500 native plants. More than 40% of these are endemic - they are found nowhere else in the world. Understanding how these endemic plants will fare under California's changing climate is the first step towards protecting this rich biodiversity legacy.

Three factors influence the severity of the projected impact of climate change over the next 80 years. First, how much CO2 will societies release into the atmosphere in the coming years? Second, how sensitive will climate change be to these emissions? Third, will plants be able to keep pace with climate change and move to suitable areas.

We explored 8 scenarios that cover a range of answers to these three factors. We used two modeling approaches. Click here to see diversity projections modeled with Maxent. Click here to see diversity projections modeled with a multi-level generalized linear model. We found that up to 66% of plants may experience range reductions of 80% or more. If they are able to disperse in time, we project that plants will move an average of up to 151 kilometers to catch up with changing climate. But these plants may move in very different directions, potentially breaking up familiar California native plant associations. While we project that the bulk of plant diversity will shift northward and towards the coast, the places where plants hardest hit by climate change will persist are in mountains and foothills scattered across the state. We map these climate change refugia and advocate their protection.

Policy can influence the first and last of the three questions. By switching to renewable forms of energy, we can significantly reduce CO2 emissions. We can increase the ability of plants to disperse to climate change refugia with stepping stones of native vegetation across the state. The California Native Plant Society can help community members get involved restoring native vegetation and choosing native plants for your backyard. Many plants are dispersed by animals, corridors that allow animals to move between these stepping stones may be crucial.

Below are fifteen examples of projected plant ranges in the present day and 80 years from now. Each map shows four future scenarios with and without plant dispersal. The scenarios differ in the level of future CO2 emissions (lower and higher) and the sensitivity of climate to these emissions (more and less).

Click on a plant to view range projections