Global warming may be an unintended consequence of the EPA rule on sulfur

weather-coldThe Environmental Protection Agency has set new standards that will require reduction of sulfur in gasoline from 30 ppm to 10 ppm by 2017 in an effort to reduce smog and haze. Gasoline typically contains 10 ppm to 80 ppm (avg. 30 ppm) sulfur. The EPA estimates that the rules, once phased in, would raise the cost of a gallon of gasoline by 0.65 cents and the price of a new vehicle by $72. The total cost in 2017 will be $1.1 billion.

Auto companies and others praise the regulation because it provides a national standard (rather than many different state standards) for tailpipe emissions (see Mick Tellson’s ADI article here) and lower sulfur makes emissions compliance easier because over time, sulfur builds up in an automobile’s catalytic converter, making it less effective. Some studies show that this effect is not reversible in older vehicles under normal driving conditions
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Refiners don’t like the rule because it adds to their operating and capital costs. According to a story in the Arizona Daily Star, “The American Petroleum Institute, which represents the oil and gas industry, pointed to studies it has commissioned estimating that the limits would add 6 cents to 9 cents a gallon to refiners’ manufacturing costs while requiring $10 billion in capital costs.” That implies that the rise in gasoline prices will be more than ten times the EPA estimate.

There is another issue that I have not seen discussed in the press. Sulfur dioxide emissions from burning gasoline and coal, or emitted from volcanoes, form aerosols that scatter light and keep the planet cooler than it would be with perfectly clear skies. According to NASA: “Aerosols interact both directly and indirectly with the Earth’s radiation budget and climate. As a direct effect, the aerosols scatter sunlight directly back into space. As an indirect effect, aerosols in the lower atmosphere can modify the size of cloud particles, changing how the clouds reflect and absorb sunlight, thereby affecting the Earth’s energy budget.”

A study in Europe found that cleaning-up of European air pollution over the past three decades has been responsible for much of the significant warming of that part of the planet over the same time span. (See here for a summary of that research.)

Since the EPA has been so hyper about the alleged warming effects of carbon dioxide emissions, I find it ironic that their own rules on sulfur will contribute to global warming.

Reference:

Vautard, R., Yiou, P. and van Oldenborgh, G.J. 2009. Decline of fog, mist and haze in Europe over the past 30 years. Nature Geoscience 2: 115-119.

See also:

Climate change in perspective
Failure of climate models shows that carbon dioxide does not drive global temperature