From the International Institute for Applied Systems Analysis: Economy main factor in US emissions decline
From 2007 to 2013, US carbon dioxide emissions from fossil fuels decreased by about 11%. This decline was widely attributed to a shift from coal to natural gas in US electricity production. However, a new analysis published in the journal Nature Communications shows that, in fact, the recent economic recession accounts for the majority of the decline.
“Natural gas emits half as much CO2 as coal when used to make electricity,” explains IIASA researcher and University of Maryland professor Laixiang Sun, who conducted the study with colleagues at the University of Maryland. However, he says, “This calculation fails to take into account the release of methane from natural-gas wells and pipelines, which also contributes to climate change.”
In the United States, coal-powered electricity went from 50% to 37% of the generation mix between 2007 and 2012, with the bulk of it replaced by natural gas, in large part due to new hydraulic fracturing, or fracking, and underground mapping technologies. Because this shift occurred at the same time as the reduction in emissions, many commentators linked the two.
Yet in addition to the economy, other factors such as population growth and energy efficiency also affect total emissions. Before the new study, nobody had analyzed the various causes of the decline in a quantitative, systematic way.
“If we don’t understand the factors that led to this emissions reduction, we won’t know how to effectively reduce emissions in the future,” says University of Maryland professor Klaus Hubacek, who is also an alumnus of IIASA’s Young Scientists Summer Program.
To tease out the causes of the decline in emissions researchers used a method known as Structural Decomposition Analysis to tease apart the various contributions of six different factors related to energy use and CO2 emissions. Using this method, they were able to determine the relative influence of changes in population, amount and patterns of consumption, production structure, and changes in fuel mix on total emissions of greenhouse gases.
The study found that from 1997 to 2007, a period of rising emissions, 71% of the increase was due to increase in US consumption of goods and services, with the remainder due to population growth. From 2007 to 2009, when emissions declined the most, the study finds that 83% of the decrease was due to economic factors including consumption and production changes, and just 17% of the decline related to changes in the fuel mix. After 2009, emissions declined by only about 1%, and this was due to a mix of all three factors.
Knowing the relative influence of such factors on emissions is important for making effective plans and policies for future climate mitigation, the researchers say. In particular, the researchers say, the study may indicate that further increase in use of natural gas may not have major benefits for the climate. While natural gas can substitute for coal, research also shows that cheap and abundant natural gas can limit the growth of carbon neutral energy sources including solar, wind, and nuclear.
Sun explains, “Sustaining economic growth while also drastically reducing emissions to the levels targeted by the Obama Administration will depend upon large additional decreases in the energy intensity of the U.S. economy, as well as radical decarbonization of the energy sector.”
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Reference
Feng K, Davis SJ, Sun L, Hubacek K. 2015. Drivers of the US CO2 emissions 1997-2013. Nature Communications. doi: 10.1038/NCOMMS8714
Part of understanding climate change comes from discovering what does NOT cause it.
Atmospheric carbon dioxide has been higher than now (usually several times higher) for most of the existence of earth. It is required for life as we know it. If it had any effect on climate, we wouldn’t be here to fuss over it.
Spot on.
‘Sun explains, “Sustaining economic growth while also drastically reducing emissions to the levels targeted by the Obama Administration will depend upon large additional decreases in the energy intensity of the U.S. economy, as well as radical decarbonization of the energy sector.”’
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gains, condensed, a strong correlation:
mass starvation + raised mortality leaves the greens large depopulized fields to reconquest: the sustainable dream.
Sun + Obama Administration: in advent of a winning team.
Color me skeptical about CO2 emissions estimates. First of all, they aren’t measured, they’re calculated from the amount and type of fuel burned, derived from the chemical composition of the fuel. There are large margins of error. Statistical methods are then applied to sketchy estimates to tease out essentially whatever result the researchers desire. All this statistical analysis of fuel consumption, global temperatures, ocean pH, radiative forcing, as well as epidemiological studies that tell us one thing about diet and human health one year and contradict it a few years later seems very sciencey but in fact isn’t far removed from reading tea leaves and entrails. There’s a great scene in “Willow” that illustrates this. The village shaman is trying to determine who will undertake the quest to return the alien child to its home. He declares to the assembly, “I will consult the bones!” After gazing at the bones for a bit, he says under his breath, “The bones tell me nothing.” He then asks Willow quietly, “Have you any love for this child?” When Willow responds affirmatively, the shaman shouts, “The bones have spoken!”
That’s how I view conclusions drawn from statistical analysis of essentially chaotic systems. The bones have spoken!
Emissions went up while the economy was growing (up to 2007) and down since the financial, economic, monetary, and state deficit and debt crisis.
Please note that none of this is the result of any planning or voluntarism for decarbonation,
The economy was “decoupling” from emissions of pollutants even before we had a strong anti-pollution policy. You’ll see this in the chart in the first link below. It started well before the central planners created the EPA. Chalk it up to economic actors, driven by dynamic competitive market forces, continuously striving to improve manufacturing, mining, drilling and all other processes to get an edge to become more efficient.
https://twitter.com/MaxCRoser/status/590226839546691584
And here’s one of my favorite charts from the EPA. There is so much information packed into one simple graph that can be analyzed and draw conclusions about trends in the economy.
http://www.epa.gov/airtrends/images/y70_13.png
The most obvious is that economic growth is not dependent on either more pollution or more CO2. Expect this trend to continue as the economy shifts away from physical stuff and focuses more on services and information. Another thing to note is that as depicted in the “energy consumption” graph, the miles driven by Americans seems to have peaked. Yet each new generation of vehicle is more fuel efficient than the previous, so that is also putting downward pressure on CO2 and pollution emissions. And all of this has happened while the population has increased by several tens of millions of people. It’s why I think Jesse Ausubel may be right that CO2 emissions in the U.S. may have already peaked regardless of what the central planners do.
” the central planners created the EPA”
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The EPA was created by a presidential executive order, issued by Richard Nixon.
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http://www.gpo.gov/fdsys/pkg/STATUTE-84/pdf/STATUTE-84-Pg2086.pdf