15 October 2009

Understanding Decarbonization of the US Economy in 2008

I have been asked by a reporter how to explain how much of the 2008 reduction in U.S. carbon dioxide emissions is due to changes in energy intensity and carbon intensity versus the slowdown in economic growth. The answer can be determined from the graph and figures above.

In 2008 year-over-year improvements (i.e., a smaller number is a larger improvement) in carbon intensity and energy intensity were slightly greater than the 10-year averages, but no where close to record levels. For instance, improvements were both smaller than in 2006, which had much higher economic growth and decreasing emissions. The data show that there is no evidence that there has been any departure from business-as-usual behavior of carbon intensity and energy intensity, and thus the overall decarbonization of the U.S. economy. Couple this with the fact that some of the changes in energy intensity and carbon intensity in 2008 were likely motivated by the state of the economy, there is no evidence of shifts in the U.S. economy that would lead to anything other than increasing emissions at business-as-usual levels (which was an 0.7% annual increase 1999-2007) as the economy recovers.

The calculations above come from the Kaya Identity, which says that:

Carbon Dioxide Emissions = GDP * Energy Intensity (TEC/GDP) * Carbon Intensity (CO2/TEC)

Sources:

GDP
CO2
Total Energy Consumption (TEC)

1 comment:

  1. It's my guess that one thing that drives a reduction in CO2 emissions is an increase in petroleum prices during the period of peak usage. Last summer with the weak economy, we didn't see prices go through the roof like they did the previous two years.

    This observation is certainly consistent with the shift in behavior we saw in 2006.

    Assuming an economic recovery next year, it's likely that we will see summer petroleum prices to skyrocket again, and, as energy prices soar, adjustments in usage by businesses...which in turn will be reflected in a net drop in CO2 emissions.

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