America’s greenhouse gas emissions fell 1.6% in 2011 even as the economic recovery continued, however anemically, according to the US government’s annual accounting of carbon pollution.
Carbon emissions usually track with the economy: When business is booming emissions rise with electricity and petroleum consumption and when times are bad emissions drop as factories sit idle and consumers shop and drive less.
For instance, emissions rose 2.4% in 2000, the last year of the first dot-com boom, and then plunged 1.7% when the bubble burst. The fall was even more dramatic during the great subprime mortgage meltdown—emissions dropped 3.3% in 2008 and 6.6% in 2009. Then as the economy began to slowly rebound in 2010, emissions jumped 3.4%, the largest one-year spike in the 21 years the EPA has been conducting the inventory.
Strange. But stranger still was the 1.6% fall in 2011–the last year comprehensive emissions data is available–as the economic recovery plodded on, albeit at a slower pace.
The answer is in the data released by the US Environmental Protection Agency yesterday, April 15. It shows that it is possible to decouple economic growth and growth in greenhouse gas emissions—or at least slow the overall upward trajectory.
It’s all about the fuel mix, given that electricity and transportation together account for 61% of America’s greenhouse gas emissions. According to the EPA, carbon-intensive coal consumption rose 5.4% in 2010, the largest one-year increase since 1991, as manufacturing rebounded. Meanwhile, the sweltering summer of 2010 resulted in record air conditioning use and a corresponding jump in electricity consumption.
But by 2011 a glut of cleaner-burning natural gas shifted power production away from coal, resulting in a 2.4% drop in emissions from electricity. Growing electricity production from renewable sources such as wind and solar also helped reduce the carbon intensity of power production. An increase in petroleum prices prompted drivers to curb their time on the road, resulting in a fall in transportation-related emissions. The increasing fuel efficiency of vehicles, mandated by the US government, also contributed to the trend. In other words, cheap natural gas and pricey petroleum is the ticket. (Plus the mild winter of 2011 helped.)
And don’t forget the trees. According to the EPA, changes in land use that resulted in more forest cover helped offset 16.1% of the US’s carbon emissions in 2011. Carbon sequestration has increased overall by 13.9% since 1991.
But don’t feel too smug. Despite the recent drop, America’s overall greenhouse gas emissions were still 9.9% higher in 2011 than they were in 1991.
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