Greenhouse Gas Emissions

An annual report finds that while worldwide carbon dioxide emissions have been steady for three years, methane and nitrous oxide emissions are up through 2012.

Nitrous oxide emissions could get much worse as a result of global warming. Arctic permafrost contains roughly 67 billion tons of the gas, and, as that ice layer thaws, up to one-fourth of the region could become a net emitter, according to a study published in July.

The U.S. could be responsible for up to 60 percent of the global spike in human-caused atmospheric methane emissions since 2002, a Harvard University study found last year. The researchers said there was too little data to identify specific sources, but the increase tracked the boom in shale oil and gas production across the country, which leaks large amounts of methane from wells and pipelines.

Update (November 13):  A report to the climate summit projects an increase in emissions from fossil fuels for 2017. Emissions had been roughly stable through 2016.