Atmospheric scientist Mark Jacobson of
To determine how variations in CO2 would modulate these different variables, Jacobson ran his model in two ways: once with 2006 CO2 levels, and again with preindustrial levels from the year 1750. After analyzing pollution levels for carcinogens, ozone, and particulates, Jacobson found that each degree of warming caused by CO2 could be responsible for roughly 1000 deaths to the 50,000 to 100,000 annual deaths in the U.S. related to air pollution, he reports in an issue of Geophysical Research Letters published earlier this month. "You're not seeing a huge percentage of deaths, … but in terms of absolute numbers, it's still a lot of people," Jacobson says. Even more important than the total number, he argues, is the model's suggestion that climate change has the greatest pollution-related impact in areas that are already heavily polluted.
"This work adds an important component to our overall understanding of the links between greenhouse gas emissions and adverse health impacts today," says Kim Knowlton of