The Heat Is Online

California Impacts Projected to be Extreme

Global Warming Menaces California Wine Industry

Reuters News Service, Aug 16, 2004

WASHINGTON (Reuters) - California will become hotter and drier by the end of the century, menacing the valuable wine and dairy industries, even if dramatic steps are taken to curb global warming, researchers said on Monday.

The first study to specifically forecast the impact of global warming on a U.S. state also shows the snowpack melting in the Sierra Nevada mountains, more frequent heat waves hitting Los Angles and disruptions to crop irrigation.

Researchers from the Carnegie Institution's Department of Global Ecology in Stanford, the Union of Concerned Scientists, the National Center for Atmospheric Research and elsewhere ran scenarios through new computer models of global warming.

All predicted California's weather would be hotter and drier, but this would be worse if only weak action is taken to reduce emissions of carbon dioxide and other greenhouse gases contributing to warming the planet.

"We are already in a situation where we have seen some warming and we have seen some impacts," said Carnegie's Christopher Field, who led the study.

"If we stay on higher emissions trajectory, there will be consequences over the coming decades that are truly, truly serious and something I think reasonable people would be doing whatever they could to avoid," he said in a telephone interview.

Writing in the Proceedings of the National Academy of Sciences, Field and colleagues described the impact based on scenarios devised by the Intergovernmental Panel on Climate Change.

One forecast, the so-called high emissions trajectory, is what Field described as business as usual. "High economic growth, high globalization and a strong emphasis on fossil fuels," he said.

The low-emissions trajectory has slightly lower economic growth with industries shifted from factories toward service industries and information technology.QUADRUPLED EMISSIONS

Under the highest-emissions forecast, carbon emissions by the end of the century will be 28 billion tons of carbon per year -- about four times the current rate of 6 billion to 7 billion tons a year. The low-emission scenario forecasts the emissions would stay at the current level.

"By the end of the century under the (best) scenario, heat waves and extreme heat in Los Angeles quadruple in frequency while heat-related mortality increases two to three times; alpine/subalpine forests are reduced by 50 percent to 75 percent and Sierra snowpack is reduced 30 percent to 70 percent," Field and his colleagues wrote.

Under the worst scenario, heat waves in Los Angeles are six to eight times more frequent, with up to seven times as many heat-related deaths as now. The Sierra snowpack falls by 90 percent.

This could "fundamentally disrupt California's water rights system," the researchers wrote. They estimated that the $3.8 billion a year dairy industry and the

$3.2 billion dollar grape industry would be especially vulnerable.

California, which has taken stronger action than other states to reduce emissions, for example with strict requirements for vehicles, cannot save itself, Field said.

"California has something like 2 percent of the world's total global greenhouse emissions," he noted.

"Even if California were to aggressively adopt emissions controls, global climate wouldn't respond to that directly. But if California is proactive, that could inspire the rest of the U.S. to be proactive, which could inspire the rest of the world, and you would see a domino effect."

© Copyright Reuters 2004. All rights reserved.


Published online before print August 16, 2004
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0404500101
Emissions pathways, climate change, and impacts on California

Katharine Hayhoe a,b, Daniel Cayan c, Christopher B. Field d, Peter C. Frumhoff e, Edwin P. Maurer f, Norman L. Miller g, Susanne C. Moser h, Stephen H. Schneider i, Kimberly Nicholas Cahill d, Elsa E. Cleland d, Larry Dale g, Ray Drapek j, R. Michael Hanemann k, Laurence S. Kalkstein l, James Lenihan j, Claire K. Lunch d, Ronald P. Neilson j, Scott C. Sheridan m, and Julia H. Verville e

aATMOS Research and Consulting, 809 West Colfax Avenue, South Bend, IN 46601; cClimate Research Division, The Scripps Institution of Oceanography, and Water Resources Division, U.S. Geological Survey, 9500 Gilman Drive, La Jolla, CA 92093-0224; dDepartment of Global Ecology, Carnegie Institution of Washington, 260 Panama Street, Stanford, CA 94305; eUnion of Concerned Scientists, Two Brattle Square, Cambridge, MA 02238; fCivil Engineering Department, Santa Clara University, Santa Clara, CA 95053; gAtmosphere and Ocean Sciences Group, Earth Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720; hEnvironmental and Societal Impacts Group, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307; iDepartment of Biological Sciences and Institute for International Studies, Stanford University, Stanford, CA 94305; jCorvallis Forestry Sciences Laboratory, U.S. Department of Agriculture Forest Service, 3200 SW Jefferson Way, Corvallis, OR 97331; kDepartment of Agricultural and Resource Economics, University of California, Berkeley, CA 94720; lCenter for Climatic Research, Department of Geography, University of Delaware, Newark, DE 19716; and mDepartment of Geography, Kent State University, Kent, OH 44242

Contributed by Christopher B. Field, June 23, 2004

The magnitude of future climate change depends substantially on the greenhouse gas emission pathways we choose. Here we explore the implications of the highest and lowest Intergovernmental Panel on Climate Change emissions pathways for climate change and associated impacts in California. Based on climate projections from two state-of-the-art climate models with low and medium sensitivity (Parallel Climate Model and Hadley Centre Climate Model, version 3, respectively), we find that annual temperature increases nearly double from the lower B1 to the higher A1fi emissions scenario before 2100. Three of four simulations also show greater increases in summer temperatures as compared with winter. Extreme heat and the associated impacts on a range of temperature-sensitive sectors are substantially greater under the higher emissions scenario, with some interscenario differences apparent before midcentury.

By the end of the century under the B1 scenario, heatwaves and extreme heat in Los Angeles quadruple in frequency while heat-related mortality increases two to three times; alpine/subalpine forests are reduced by 50-75%; and Sierra snowpack is reduced 30-70%. Under A1fi, heatwaves in Los Angeles are six to eight times more frequent, with heat-related excess mortality increasing five to seven times; alpine/subalpine forests are reduced by 75-90%; and snowpack declines 73-90%, with cascading impacts on runoff and streamflow that, combined with projected modest declines in winter precipitation, could fundamentally disrupt California's water rights system. Although interscenario differences in climate impacts and costs of adaptation emerge mainly in the second half of the century, they are strongly dependent on emissions from preceding decades.

bTo whom correspondence should be addressed.

Katharine Hayhoe, E-mail: