Environment News Service: Americans across the country face a 70 percent increase in unhealthy summertime ozone levels by 2050, find scientists at the National Center for Atmospheric Research in Boulder working with one of the world's most powerful computers. This is because warmer temperatures, higher atmospheric levels of methane, and other atmospheric impacts of a changing climate, spur chemical reactions that form ground-level ozone. "It doesn't matter where you are in the United States -- climate change has the potential...