A new study by a Stanford scientist has outlined for the first time the direct links between increased levels of carbon dioxide in the environment and increases in human mortality.
The study was carried out using the help of a new computer model of the atmosphere that incorporates scores of physical and chemical environmental processes.
Developed by Mark Jacobson, a professor of civil and environmental engineering at Stanford, the computer model is considered by many to be the most complex and complete atmospheric model worldwide.
It incorporates principles of gas and particle emissions and transport, gas chemistry, particle production and evolution, ocean processes, soil processes, and the atmospheric effects of rain, winds, sunlight, heat and clouds, among other factors.
According to Jacobson, while it has long been known that carbon dioxide emissions contribute to climate change, the new study details how for each increase of one degree Celsius caused by carbon dioxide, the resulting air pollution would lead annually to about a thousand additional deaths and many more cases of respiratory illness and asthma in the United States.
Worldwide, upward of 20,000 air-pollution-related deaths per year per degree Celsius may be due to this greenhouse gas.
For this 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.
The study states that ozone causes and worsens respiratory and cardiovascular illnesses, emphysema and asthma, and many published studies have associated increased ozone with higher mortality.
"Ozone is a very corrosive gas, it erodes rubber and statues," said Jacobson said. "It cracks tires. So you can imagine what it does to your lungs in high enough concentrations," he added.
Jacobson arrived at his results of the impact of carbon dioxide globally and, at higher resolution, over the United States by modeling the changes that would occur when all current human and natural gas and particle emissions were considered versus considering all such emissions except human-emitted carbon dioxide.
"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," said Jacobson.
"The simulations accounted for the changes in ozone and particles through chemistry, transport, clouds, emissions and other processes that affect pollution. Carbon dioxide definitely caused these changes, because that was the only input that was varied," he added.
"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 the health effects would grow worse if temperatures continue to rise," said Jacobson.