News Release

California’s environment threatened by global warming

Peer-Reviewed Publication

Union of Concerned Scientists

A new two-year study by California's leading ecological scientists concludes that climate change poses a range of serious challenges for the state's environment and economy. Drawing on the scientific consensus that predicts California's future climate will be warmer and wetter in winters and hotter in summers, the report finds that there will be less water to go around in an already thirsty state. The scientists foresee a range of likely impacts, from altered commercial fisheries to increased difficulty protecting rare and endangered species. Dramatic impacts -- from floods, landslides and wildfires, to disease and pest outbreaks -- are very real possibilities.

"Many of the places we know and love in California are vulnerable to a changing climate," said the lead author of the report, Dr. Chris Field from the Carnegie Institution. "A variety of changes are coming, and many will have profound ecological and economic consequences. We should act now, incorporating science as we plan for California's future."

Confronting Climate Change in California: Ecological Impacts on the Golden State is a joint effort by the Ecological Society of America and the Union of Concerned Scientists. Leading ecological scientists at the Carnegie Institution, Stanford University, the University of California at Santa Barbara, and the Lawrence Berkeley National Laboratory produced the report. The research was overseen by a seven-member steering committee of preeminent global-change scientists from across the United States. The report represents the current state of scientific knowledge about the impacts of climate change on California's unique environments.

The best available climate models report that by 2030-2050 winters are likely to warm by 5-6° F, and summers to warm by 1-2° F. Given the higher temperatures, the report says an increase in winter precipitation will fall mostly as rain rather than snow. Thus, less water will be stored in the snow pack while more water will run off immediately, adding to winter flooding and landslide problems. Flood controls and levees in coastal areas would be increasingly challenged, requiring additional management responses to protect valuable ecosystems and human structures. The change in the water cycle will likely lead to water shortages during the late spring and summer, thus worsening drought conditions, irrigation needs, and water-use conflicts. Crops that require large amounts of irrigation water (such as grapes, cotton, and alfalfa) will be among the hardest hit.

"There will be too much water at the wrong time and too little when we need it," said Dr. John Melack from the University of California at Santa Barbara. "California could see more drenched winters and parched summers."

Warmer summers will tend to intensify the summer drought, potentially leading to hotter, harder-to-control wildfires, especially if Santa Ana winds increase. Higher temperatures will warm the ocean and likely raise the sea level 8 to 12 inches by 2100, amplifying current problems with storm surge, beach erosion, and flooding during major winter storms. The report also points to evidence that El Niño may become more frequent with climate change, with stronger La Niña phases.

"Major floods and wildfires could become more frequent," said co-author Dr. Frank Davis from the University of California at Santa Barbara.

The combination of water and temperature changes poses problems for plants and animals, including threatened and endangered species. Wildlife, forests, and grasslands will tend to shift north and upward to more suitable habitats unless development or other obstacles hem them in. The species with the least ability to colonize new habitats will have the biggest problems. The study finds that there are already major shifts in California's ocean life, including decreases in zooplankton, sea bird populations, and northern cold-water species, but increases in southern warm-water species. Shifts in the abundance of disease-carrying animals, such as rodents with hantavirus, may pose difficult challenges to the public health care system.

"We are putting our inheritance from nature in jeopardy," said co-author Dr. Gretchen Daily from Stanford University. "The long-term health of California's most spectacular natural treasures, from redwoods to giant kelp, is at risk."

The scientists note that a changing climate will exacerbate problems in California caused by intensive development and rapid population growth. Every step taken today to protect the diversity of California's natural resources will also benefit public safety, recreation, agriculture, fisheries, forestry, and the state's unique natural heritage. Reducing emissions from automobiles and power plants is the most important step to curbing global warming. Limiting the impacts of development on the natural landscape is also critical, especially in areas vulnerable to species and habitat loss.

"California's climate is at the heart of its quality of life and economy," said steering committee member Dr. Peter Frumhoff, Director of Global Resources at the Union of Concerned Scientists. "Californians can take action now that will make a difference for the state and the world."


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