In a groundbreaking study, Stanford University researchers have linked the increase in atmospheric carbon dioxide to an increase in mortality.
While an increase in carbon dioxide emissions has previously been linked to global warming, the Stanford study is the first to make a direct connection to an increase in the mortality rate.
The study indicates that each increase of 1 Celsius degree caused by carbon dioxide will result in an additional 1,000 deaths in the United States each year.
"This is a cause and effect relationship, not just a correlation," Mark Jacobson, professor of civil and environmental engineering, said. His study, to be published in Geophysical Research Letters, concludes that upwards of 20,000 air-pollution-related deaths per year globally may be caused by an increase in carbon dioxide emissions.
"The study is the first to specifically isolate carbon dioxide's effect from 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 said.
California is home to six of the 10 U.S. cities with the worst air quality, so the effects of increased carbon dioxide emissions are resulting in proportionately greater amount of deaths.
Jacobson said that about 30 percent of the "excess" deaths nationally caused by carbon dioxide emissions now occur in California, which has 12 percent of the country's population.
"That alone creates a special circumstance for the state," Jacobson said. The six cities are Los Angeles, Bakersfield, Visalia, Fresno, Merced and Sacramento.