Jan 3 - McClatchy-Tribune Regional News - John Woolfolk San Jose Mercury News, Calif.

Hundreds more people in the United States will die each year from air pollution as temperatures increase from carbon dioxide, the greenhouse gas blamed for global warming, according to a new Stanford University study.

The study by Mark Z. Jacobson, a professor of civil and environmental engineering, is considered the first to directly link increased carbon dioxide, or CO, in the air to human deaths. It is expected to be published today in the journal Geophysical Research Letters.

"I think this is really important because it definitively in my mind shows the causal effect of CO on health," Jacobson said.

The study also shows that the deadly effects of carbon dioxide intensify in areas like many major California cities that already suffer from poor air quality.

"Climate change impacts air pollution more where air pollution is already high," Jacobson said. "It has huge implications. California bears the brunt of climate change in terms of air pollution health problems."

The study comes as California officials sued the federal government in a bid to reverse a decision last month denying California a waiver needed so the state can impose its own laws to regulate greenhouse gases from new cars and trucks.

State officials reached Wednesday had not yet seen the Stanford study but said its conclusions bolster their argument that the state suffers more than many others from the effects of global warming.

"The results don't surprise me," said

BreAnda Northcutt, deputy communications secretary for the California Environmental Protection Agency. "Rising temperatures will certainly worsen our air quality."

Jacobson said his research, based upon a state-of-the-art computer model of the atmosphere that incorporates scores of physical and chemical environmental processes, shows that carbon dioxide can directly affect human health.

The research predicts that carbon dioxide may increase annual U.S. air pollution deaths by about 1,000, although it could range from 350 to 1,800, and cancers by 20 to 30 for every 1-degree Celsius increase in temperature caused by gas. Globally, deaths could increase by about 21,600 a year, ranging from 7,400 to 39,000, the study said.

A degree Celsius -- the preferred scale among scientists -- is greater than a degree Fahrenheit commonly used in the United States. Under the Celsius scale, water at sea level freezes at 0 degrees and boils at 100. In the Fahrenheit scale, it freezes at 32 degrees and boils at 212.

Carbon dioxide is called a greenhouse gas because it acts like a window pane, letting light through but trapping heat.

California is home to seven of the 10 worst metropolitan areas for ozone pollution in the United States -- Los Angeles, Fresno, Bakersfield, Visalia, Merced, Sacramento and Hanford -- according to the American Lung Association.

According to Jacobson, more than 30 percent of the estimated 1,000 annual additional U.S. deaths caused by carbon dioxide would occur in California, which has a population of about 12 percent of the United States.

For the study, Jacobson used the computer model to determine the amounts of ozone and airborne particles that result from temperature increases, caused by increases in carbon dioxide emissions. Ozone causes and worsens respiratory and cardiovascular illnesses including emphysema and asthma, and has been linked to higher human mortality.

He found that higher temperatures caused by carbon dioxide increased the chemical rate of ozone production in urban areas. He also found that increased water vapor caused by carbon dioxide-induced higher temperatures boosted chemical ozone production even more in urban areas.

Contact John Woolfolk at jwoolfolk@mercurynews.com or (408) 975-9346.