Assessing the Climate Change in California’s Ecoregions

California, an ecologically and biologically diverse state, has 13-level III ecoregions identified by Environmental Protection Agency. They support the state’s wide range of economic activities from the water supply, and agriculture to recreational activities and are the homes of many endemic species and various aquatic habitats. But changes in climate can impact the economy and biodiversity of these ecoregions by dwindling water supply and loss or ecosystem degradation. This research is to assess climatic trends in the thirteen ecoregions and identify impacted ecoregions to better initiate and manage mitigation actions.
Climatic change is examined by analyzing trends in several indices of daily temperature and precipitation data from 468 ground observation stations across the state for the periods 1950–2020. The indices of temperature and precipitation extremes are selected from the list of climate change indices recommended by the World Meteorological Organization–Commission for Climatology (WMO–CCL) and the Research Program on Climate Variability and Predictability (CLIVAR). A set of 10 indices of climate extremes are selected that includes six temperature and four precipitation indices. Initial analysis of the temperature indices indicates the occurrence of fewer cold nights, cold days, and frost days, and conversely more warm nights, warm days, and summer days across the state. Analysis of precipitation indices – maximum annual precipitation, number of precipitation days with precipitation greater than 10 mm, and number of days with precipitation amount above a site-specific threshold value for moderate and very wet days will be presented along with the analysis of temperature indices.