The National Oceanic and Atmospheric Administration reports that carbon dioxide concentrations have increased at an accelerating rate, and that, perhaps more troublingly, methane levels are starting to go up, too:
The agency said atmospheric levels of carbon dioxide reached nearly 385 parts per million last year, up from 280 in 1850 and an increase of 2.6 parts per million from 2006, chiefly from the burning of fossil fuels. The methane situation is less clear. Methane is produced naturally by swamps but also by activities including burning fossil fuels. The issue is important because climate experts have long worried that if Arctic permafrost thaws, the process would release potentially catastrophic amounts of methane into the atmosphere. In a statement, the agency said the most likely causes of the methane increase were economic development in Asia and emissions from Arctic wetlands. It said it was “too soon to tell” if the increase signals an Arctic thaw.