Summary:Researchers say fossil fuel burning and other human activities caused nearly all the rapid warming o

Researchers say fossil fuel burning and other human activities caused nearly all the rapid warming of the past decade.

By Bob Berwyn

Former federal climate experts warn that atmospheric carbon dioxide concentrations hit a record high in May and that the monthly average global temperature this summer could rise as much as 3.5 degrees Fahrenheit (1.9 degrees Celsius) above the pre-industrial benchmark used to measure the heating from greenhouse gases.