Many people say that the boom in natural gas production over the last decade has had at least one positive side effect: Fracking is widely thought to be the impetus behind an unprecedented decline in carbon emissions in the United States.
But that line of thinking isn't really true, according to a new study. Instead, it was actually the economic recession that led to declining emissions between 2007 and 2013—and that spells trouble for U.S. efforts to combat climate change.
"Sustaining economic growth while also drastically reducing emissions to the levels targeted by the Obama administration will depend upon large additional decreases in the energy intensity of the US economy as well as radical decarbonization of the energy sector," Kuishuang Feng, Steven J. Davis, Laixiang Sun, and Klaus Hubacek write today in Nature Communications.
From 2007 to 2009, when emissions decreased by nearly 10 percent, the data revealed that 53 percent of that drop resulted simply from consumers (and manufacturers) buying less stuff.
In 2012, the U.S. saw an 18-year low in carbon emissions. This was viewed as cause for cautious optimism, if not celebration. That same year, the economy grew by about three percent and the population continued to rise—evidence to many that a concurrent shift toward natural gas was behind the drop in emissions. But even as official reports supported that view, they also hinted that the economy was playing a bigger role. For one thing, mild winters and unusually low natural gas prices were partly responsible for the shift away from coal, and those factors could easily change.
And yet, Feng and his colleagues at the University of Maryland observed, no one seemed to have done a rigorous analysis to back up claims that the move to natural gas caused the emissions decline. So Feng and his team conducted their own. For their analysis, the researchers drew on data from the U.S. Energy Information Agency emissions and the Bureau of Economic Analysis, describing the inputs, including individual energy sources, that go into producing the products and services we consume.
From 2007 to 2009, when emissions decreased by nearly 10 percent, the data revealed that 53 percent of that drop resulted simply from consumers (and manufacturers) buying less stuff—make less stuff, and you use less energy. Meanwhile, only 17 percent of the decline in emissions was a result of replacing coal with natural gas. But as the economy recovered between 2009 and 2013, emissions fell only slightly. The shift toward natural gas, structural changes in the manufacturing industry, and slight drops in consumption managed to just barely offset the effects of a growing economy and ever-increasing populations.
"Although increased use of natural gas by the energy sector has helped to keep U.S. CO2 emissions from rising during the economic recovery," the team writes, "our decomposition analysis shows that decreases in the energy intensity of the manufacturing, transport and service sectors over the same period were even more important." The researchers argue that lasting emissions reductions will depend on policies, such as the Environmental Protection Agency's Clean Power Plan, which could ensure the trend toward more efficient, low-carbon energy sources.
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