How the U.S. Became an Unlikely Leader in Reducing Carbon Emissions

"Who would have thought the United States would one day be a leader in cutting greenhouse gas emissions?" asks Porter. "Yet when President Obama talked about the nation’s energy revolution during his State of the Union address last month, he could have boasted that American emissions of CO2 had fallen almost 13 percent since 2007. It was perhaps the biggest decline among industrial countries, and substantially steeper than in Europe, which has been much more committed to combating climate change."

"Carbon emissions from the United States have never fallen this much," he adds, "not after the first oil price shock following the Arab oil embargo of 1973, nor after the Iranian revolution of 1979, when American drivers suddenly discovered the virtues of Japanese small cars and President Jimmy Carter installed solar panels on the White House to heat the water."

"What stands out most in this shift, however, is not environmental regulation or public concern about global warming but the price of energy and market-driven technological advancements. 'It wasn’t so much a policy shift that brought carbon emissions down,' said James Hamilton, an energy economist at the University of California, San Diego. 'It was irresistible market forces.'”

The shift from coal to gas-powered generators has been a major cause of the decline. But is the shift, which was largely due to the falling price of gas, sustainable? And, as coal use has grown at a rate "10 times that of renewables" since 2000, can other countries follow America's accidental lead in reducing emissions?