California’s winters are highly likely to become warmer and wetter over the next century, with average winter temperatures increasing by 2.7°C – 3.3°C by 2030-2050 and summer temperatures increasing by 0.5°C – 1.1°C
The Union of Concerned Scientists and the Ecological Society of America-sponsored report Confronting Climate Change in California: Ecological Impacts on the Golden State provides an assessment of the probable impacts of environmental changes on the state’s diverse bio-regions and the goods and services they provide.
Written by scientists at the Carnegie Institution, Stanford University, the University of California at Santa Barbara and the Lawrence Berkeley National Laboratory, the report concludes that climate change poses a range of serious challenges for California’s environment, economy and quality of life. Key findings include:
- Increased winter precipitation will fall mostly as rain rather than snow. Thus, less water will be stored in the snow pack while more water will runoff immediately, adding to winter flooding and landslide problems. Changes in the water cycle will probably lead to water shortages during the late spring and summer, worsening drought conditions, irrigation needs and water use conflicts. Crops that require large amounts of irrigated water, such as grapes, cotton and alfalfa, will be among the hardest hit.
- Warmer summers will tend to intensify the summer drought, potentially leading to hotter, harder-to-control wildfires, especially if Santa Ana winds also increase. Higher temperatures will warm the ocean and could raise the sea level by 20.3cm – 30.5cm over the next century, increasing current problems with high waves, beach erosion and flooding during major winter storms. Phenomena such as El Nino may become more frequent and/or more intense as the climate changes.
- The combination of water and temperature changes poses problems for plants and animals. Wildlife, forests and grasslands will tend to shift northward and upward unless development or other obstacles hem them in. The report points out that there are already major shifts in California’s marine life, with decreases in zooplankton, sea bird populations and northern cold-water fishes, and increases in southern, warm-water fishes. Shifts in the abundance of disease-carrying animals, such as rodents with hantavirus, may pose difficult challenges for the public health-care system.
The authors emphasise that a changing climate will exacerbate problems in California caused by extensive development and rapid population growth. In the light of this, they urge Californians to adopt new energy, transportation and land-use measures that reduce the emissions of greenhouse gases, and to limit the development of vulnerable habitats and areas subject to fires, floods and landslides.