Tuesday, March 23, 2010

Will the Real #1 Driver of Climate Change Please Stand Up?

As I study energy and climate, statistics fly at me from every direction and it gets really hard to sort things out. Everything, it seems, is "the largest single producer of carbon emissions" and there is no way to sort out which really is the largest.

NASA recently conducted a study of all the major sources of greenhouse gas emissions and their net effects on climate change.

Clearly, electric power production is the largest single source of C02, but it is offset by aerosol-cloud effects and sulfates that actually cause global cooling, thus the net global warming effect of electricity production is about the same as the Industry sector.

Likewise, the road transportation sector produces less C02 than the Industry and power sectors, but road transportation does not have the aerosol offsets that would reduce it's impact on global warming. Thus, while the road transportation sector produces less C02, it actually contributes more to global warming than Industry and Power—today.

However, if you look at the title of the article, it says "Road Transportation Emerges as Key Driver of Warming." While is this is true in a qualified sense (it is "a" key driver), that statement doesn't make as much sense when you look at the first graph. Electric power production produces the most C02, and in fact, the NASA data shows that in the future, assuming BAU, electric power production will continue to be the largest driver of global warming, with road transportation second. As we build cleaner power plants that produce fewer aerosols, the warming effect of power production will increase dramatically. Road Transportation as "the" key driver only appears when you look at the second graph, which is an estimate of emissions for 2020.

What the article doesn't consider is the behavioral effects of car use. Driving increases casual consumption exponentially. The reason why we shop more, eat out at restaurants more, live, work and play at greater distances, is because of the power and convenience of the automobile to get us to every destination cheaply and efficiently. Cars exponentially increase the speed and amount that we are able to consume. This increased consumption creates a demand for more products and services, which in turn creates a demand for more electric energy production and more industrial production, which also leads to an increase in road transportation. So in that sense, road transportation is indeed a KEY driver in global warming. Ecologists call this effect a "positive feedback loop."

1 comment:

  1. I'm not sure how much credit one wants to give to the aerosols etc. responsible for 'global cooling' as they are also responsible for a range of adverse health effects. Focusing only on climate change, and ignoring the wider effects on humans of various interventions in the biosphere, seems too narrow.