talking about climate change, not all fossil fuels are created equal. Burning natural gas, for instance, produces nearly half as much carbon dioxide per unit of energy compared with coal. Natural gas is thus considered by many to be a “bridge fuel” that can help nations lower carbon emissions while they transition more slowly from fossil fuels to renewable, carbon-neutral forms of energy. The recent boom in natural gas production in the United States, for instance, contributed to a 3.8 percent drop in carbon emissions in 2012.