Carbon dioxide isn't the only greenhouse gas climbing alarmingly fast. Methane is now about 1,780 parts per billion. During the last 650,000 years, it never exceeded 790 parts per billion. And worryingly, methane has begun building up in the atmosphere again after stabilizing between 1999 and 2006. Some evidence points to melting permafrost across the Northern Hemisphere, where decaying plant material produced methane that was frozen in the tundra for millennia.

Nitrous oxide (N₂0) is another greenhouse gas produced by both natural and human-related sources. Less of this gas is emitted than CO₂, but it is a more powerful heat trapper on a per molecule basis and has an atmospheric lifetime of 120 years.

Some industrial chemicals, such as fluorinated gases, are considered to be "high global warming potential gases" because of their potency and long atmospheric lifetimes. For example, nitrogen trifluoride, a cleaning agent used in making flat panel TVs, computer monitors, and thin-film solar panels, has increased 30-fold since 1978 and is thousands of times more powerful as a greenhouse gas than carbon dioxide.