ScienceDaily: If climate disasters are to be averted, atmospheric carbon dioxide (CO2) must be reduced below the levels that already exist today, according to a study published in Open Atmospheric Science Journal by a group of 10 scientists from the United States, the United Kingdom and France. The authors, who include two Yale scientists, assert that to maintain a planet similar to that on which civilization developed, an optimum CO2 level would be less than 350 ppm — a dramatic change from most …