San Diego County Ecosystems: Ecological Impacts of Climate Change on a Biodiversity Hotspot

The Mediterranean ecosystems of southern California are some of the most ecologically diverse systems outside of the tropics. The richness and diversity of plants and animals, as well as high rates of endemism, make the area a biodiversity hotspot. San Diego County is a particularly unique part of southern California, considering the region’s complex topography and highly variable precipitation and other climatic factors, which play an important role in determining the resident biological palette. Climate change would very likely aggravate parts of the already challenging climate of the region and add to other stressors. San Diego is home to a major metropolitan area, and is burdened by extensive fragmentation in the form of roadways and suburban-rural development. Within this complex, San Diego County still hosts expanses of native and preserved habitats where management and conservation action could be greatly enhanced through science-based assessments and planning for climate change and increased climate variability.

In partnership with the Climate Science Alliance – South Coast, a unique collaboration of local ecologists and climatologists conducted a review of the impacts of climate change on San Diego County’s terrestrial ecosystems. In this assessment, we review the state of the science on the natural climate variability and projected climatic changes, and describe the region’s unique diversity of ecosystems, habitats, plants, and animals. The assessment includes a review of the susceptibility of the region’s ecosystems to impacts from climate variability and relevant synergistic impacts of anthropogenic factors that may be exacerbated by a changing climate (e.g., urban growth, land use shifts, and fire regimes). We explore the most regionally-relevant climate adaptation strategies that can be applied to buffer the effects of climate variability and provide several case-study examples of adaptation projects that have been successfully implemented in San Diego’s terrestrial ecosystems. We also conducted a needs assessment to identify needed science efforts such as long-term monitoring, climate modeling and projections, and ecosystem modeling that may facilitate change detection, adaptive management, and risk planning for the region.