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Each Degree of Global Warming Linked to 20,000 Deaths a Year

STANFORD, California, January 3, 2007 (ENS) – For each increase of one degree Celsius in the global temperature caused by carbon dioxide emissions, the resulting air pollution would lead annually to about 1,000 additional deaths and many more cases of respiratory illness and asthma across the United States, finds new Stanford University research released today.

Worldwide, upward of 20,000 air pollution related deaths per year per degree Celsius may be due to heat-trapping carbon dioxide emissions, according to the paper by Mark Jacobson, a professor of civil and environmental engineering at Stanford.

The research is the first to track the health effects of carbon dioxide emissions. It documents the direct links between increased levels of carbon dioxide in the atmosphere and increases in human mortality.

For Californians the effect is even greater. Jacobson’s paper offers concrete evidence that California is facing a particularly difficult situation if carbon dioxide emissions increase.


Air pollution in Los Angeles,
California (Photo courtesy U.S. EPA)

The study finds that the effects of carbon dioxide’s warming are greatest where pollution is already severe. Given that California has six of the 10 U.S. cities with the worst air quality, the state is likely to bear an increasingly disproportionate burden of death if no new restrictions are placed on carbon dioxide emissions.

The new findings, to be published in the journal “Geophysical Research Letters,” come to light just after the U.S. Environmental Protection Agency’s ruling against states setting their own emission standards for this greenhouse gas based in part on the lack of data showing the link between carbon dioxide emissions and their health effects.

On December 19, 2007, the EPA denied California and 16 other states a waiver that would have allowed the states to set their own emission standards for carbon dioxide, which is not currently regulated. The EPA denied the waiver partly on the grounds that no special circumstances existed to warrant an exception for the states.

Stephen Johnson, the EPA administrator, said California’s petition for a waiver of federal standards was denied because the state had failed to prove the “extraordinary and compelling conditions” required to qualify for a waiver.

“With six of the 10 most polluted cities in the nation being in California, that alone creates a special circumstance for the state,” Jacobson said.

Increased warming due to carbon dioxide will worsen people’s health in those cities at a much faster clip than elsewhere in the nation, he said.

Jacobson said more than 30 percent of the 1,000 excess deaths due to each degree Celsius increase caused by carbon dioxide occurred in California, which has a population of about 12 percent of the United States.

This indicates a much higher effect of carbon dioxide-induced warming on California health than that of the nation as a whole.

“This is a cause and effect relationship, not just a correlation,” said Jacobson. “The study is the first specifically to isolate carbon dioxide’s effect from that of other global-warming agents and to find quantitatively that chemical and meteorological changes due to carbon dioxide itself increase mortality due to increased ozone, particles and carcinogens in the air.”

Jacobson used a computer model to determine the amounts of ozone and airborne particles that result from temperature increases, caused by increases in carbon dioxide emissions.

He observed that higher temperatures due to carbon dioxide increased the chemical rate of ozone production in urban areas. And he noticed that increased water vapor due to carbon dioxide-induced higher temperatures boosted chemical ozone production even more in urban areas.

“Ultimately, you inhale a greater abundance of deleterious chemicals due to carbon dioxide and the climate change associated with it, and the link appears quite solid,” he said. “The logical next step is to reduce carbon dioxide: That would reduce its warming effect and improve the health of people in the U.S. and around the world who are currently suffering from air pollution health problems associated with it.”

Jacobson added that much of the population of the United States already has been directly affected by climate change through the air they have inhaled over the last few decades and that the health effects would grow worse if temperatures continue to rise.

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