Dive Brief:
- A new study finds the bulk of the reduction in U.S. carbon dioxide emissions across a six-year period can largely be attributed to a decline in the United States' consumption of goods and services during the recession, rather than fuel switching to natural gas from coal.
- The study, supported by Austria-based International Institute for Applied Systems Analysis (IIASA) and the University of Maryland, found that emissions decreased with the recession and that 77% of the decrease from 2007 to 2009 was due to economic factors.
- Published in the journal Nature on Monday, the study concludes the United States' proposed greenhouse gas mandates are necessary to lock in the reductions and drive further pollution abatement.
Dive Insight:
The United States reduced CO2 emissions by about 11% from 2007 to 2013, and the conventional knowledge was that most of this was due to utilities switching from coal to natural gas. But a new paper from researchers in Maryland at at IIASA says a global downturn was really behind the decrease, though changes in the fuel mix did play a small part.
Across the six-year stretch the United States reduced CO2 emissions from 6,023 Mt to 5,377 Mt, but researchers note said “the factors driving the decline — and the decade of increasing emissions that preceded it,” had not quantitatively evaluated.
Their results may surprise some: Before 2007, they found rising emissions were driven by economic growth. More than 70% of the the increase between 1997 and 2007 was due to increases in U.S. consumption of goods and services, with the remainder due to population growth.
“Emissions decreased with the global economic recession: 77% of the decrease 2007-2009 was due to decreased consumption and changes in the production structure of the US economy, with just 18% related to changes in the fuel mix of the energy sector,” according to the paper's abstract.
During the ongoing economic recovery, in the subsequent four years, researchers said the overall decrease in emissions has been less than 1%, with that resulting equally from changes in the fuel mix of the energy sector, decreased energy use per unit of GDP, and changes to both production structure and consumption patterns
“We conclude that changes in fuel mix — the primary means by which substitution of gas for coal affects emissions — have had a relatively minor role in the reduction of US CO2 emissions since 2007,” the found., “Energy-climate policies such as the proposed US-EPA rules may therefore be necessary to lock-in the recent emissions reductions and drive further decarbonization of the US energy system as its economy recovers and grows “