How Did U.S. Greenhouse Gas Emissions Hit a 20-year Low?

By Bob Shively, Enerdynamics President and Lead Instructor

Over the last 10 years, we have seen arguments ebb and flow over greenhouse gas emissions and global warming. Not too long ago, federal legislation limiting carbon emissions seemed imminent. Then the economic recession, a move to the right in the House of Representatives, and intensive lobbying and public relations efforts by certain interest groups altered public perceptions, and it appeared the U.S. would not act to reduce carbon output.

But stunningly, the U.S. Energy Information Administration recently released data indicating that carbon emissions have fallen so dramatically over the last few years that emissions in the first few months of 2012 hit levels approximately equivalent to 1992 emissions. This surpasses the dreams of even the most optimistic policy writers who hoped to reduce carbon emissions through legislation.

So has everyone just simply decided on their own to be better environmental stewards? Not likely.  Rather, key contributing factors include:

  • reduced demand due to the economic downturn
  • renewable portfolio standards that have fostered increased renewable electric generation
  • increased energy efficiency efforts
  • replacement of coal-fired electricity generation by gas-fired generation

To know where we stand today, it is important to understand which of the factors are most important and whether they produce long-term or short-term effects. With the following graph we can clearly see the economic downturn is not the primary factor — economic activity measured as Gross Domestic Product (GDP) has grown significantly since 1992 while carbon emissions have returned to the 1992 level.

Using a method called “Kaya Identity” the EIA looks at causes of changes in carbon output:

Here we see a significant impact of the economic downturn in 2009, but emissions have fallen in 2011 (and as current data cited above shows they are continuing to fall in 2012) even as the economic output recovers. The largest bar for factors reducing carbon emissions in 2011 is green, indicating energy intensity. This means we are continuing to produce more economic output using less energy to do it. This is partly due to structural changes where services replace manufacturing in our economy and party due to increased energy efficiency.

We continue this discussion in our Q3 2012 issue of Energy Insider. Read the full article here:


About Enerdynamics

Enerdynamics was formed in 1995 to meet the growing demand for timely, dynamic and effective business training in the gas and electric industries. Our comprehensive education programs are focused on teaching you and your employees the business of energy. And because we have a firm grasp of what's happening in our industry on both a national and international scale, we can help you make sense of a world that often makes no sense at all.
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