HEAT SPIKE WARNED FOR L.A. SCIENTISTS ISSUE GLOBAL WARMING REPORT.

Byline: Harrison Sheppard Sacramento Bureau

If the world's population continues burning fossil fuels at the current rate, global warming could lead to more heat-related deaths in Los Angeles by the end of the century, plus severe water shortages and summers comparable to those in Death Valley, according to a study released Monday.

The study by 19 leading environmental scientists, published by the National Academy of Sciences, examined the impact of global warming on California. It found that even in a best-case scenario, with a concerted effort to reduce the use of fossil fuels, temperatures will still increase sharply by 2099, summers will be longer, and water provided by the Sierra Nevada snowpack will be in short supply.

But if there is no such effort and usage continues at its current rate, then as many as 1,182 people a year, especially the elderly and children, could die from heat-related causes in Los Angeles by the year 2099, compared to 165 a year currently.

Other effects include lengthening the heat-wave season from 115 days to 204 days and raising the average temperature by 10 degrees, or even 15 degrees, in summer.

``The 7-to-10-degree range (increase) is enough to make many coastal cities feel like inland cities do today,'' said Katharine Hayhoe, the study's lead author. ``And at the higher end of the range, with 15-degree Fahrenheit change in summer, that's enough to make summer in many of California's inland cities feel like Death Valley does today.''

The scientists say their study points to a clear need for voluntary energy conservation, as well as policies that encourage conservation and the development of more energy-efficient technologies.

While this study builds upon a large volume of previous research, some scientists remain skeptical of global warming theories.

Kenneth Green, an adjunct scholar at the Santa Monica-based Reason Public Policy Institute, said most studies of global warming oversimplify the highly complex global climate to the point where the data is nearly useless.

``The bottom line is, we have an incredibly small amount of data about the climate,'' said Green, who is also chief scientist at the Fraser Institute, a Canadian free-market think tank.

``It's spotty around the world. It's of varying - not usually good - quality and it has to be pinched, prodded, kneaded and tortured until it says something.''

He said more research is needed before society uses its precious resources to fight global warming when it could use those same resources to, for example, fight disease.

But Bill Patzert, a climate expert at the Jet Propulsion Laboratory in Pasadena, who was not involved in the study, said its authors are some of the top experts in the world and he agrees with their conclusions.

In Los Angeles, for example, Patzert said, the average temperature has increased by 5 degrees over the past century. The increase is most severe at night, when temperatures have risen by 7 degrees, compared to only 3 degrees during the day.

Warming is caused not only by global trends, he noted. California's development and population explosions over the last 100 years, with its accompanying increase in asphalt and decrease in shade trees, has contributed to a greater absorption of heat by the ground throughout the state.

Harrison Sheppard, [phone]

harrison.sheppard(at)dailynews.com

GLOBAL WARMING

A new report theorizes two possibilities for the effects of global warming in California. Under the worst-case scenario, emissions of greenhouse gases and other contributing factors to global warming occur at their current rate. Under the better scenario, we conserve more fossil fuels and develop more government policies aimed at energy efficiency. Among the possible results by 2099:

Statewide average temperatures:

Current: 59 degrees year-round; 73 degrees summer; 46 degrees winter.

Better scenario: 63-65 degrees year-round; 77-81 degrees summer; 50 degrees winter.

Worst scenario: 66-70 degrees year-round; 80-88 degrees summer; 51-53 degrees winter.

Heat-related deaths in Los Angeles:

Current: 165 per year

Better: 319 to 551 per year

Worst: 790 to 1,182 per year

Length of heat-wave season:

Current: 115 days

Better: 149 to 162 days

Worst: 178 to 204 days

Number of heat-wave days in Los Angeles:

Current: 12 days

Better: 44 to 47 days

Worst: 76 to 95 days

CAPTION(S):

box

Box:

GLOBAL WARMING (see text)