November 13, 2013 |
Society has slowed down global warming several times over the last century without even trying, new research says. A study found that the rate of global warming has ratcheted down in response to major world events, including the two world wars, the Great Depression and, most recently, a global ban on ozone-depleting substances. Researchers attribute the most recent slowdown, since the late 1990s, at least in part to the decline in emissions of chlorofluorocarbons, greenhouse gases that were phased out under the 1989 Montreal Protocol . The international treaty was not intended to fight climate change, but to protect the atmosphere's ozone layer.