Though burning natural gas produces much less greenhouse gas emissions than burning coal, a new study indicates switching over coal-fired power plants to natural gas would have a negligible effect on the changing climate.
Tom Wigley, a senior research associate at the National Center for Atmospheric Research, reports that if natural gas were substituted for coal in energy production, climate change trends would not slow down and may, in fact, accelerate. His findings are due to be published in the journal Climatic Change Letters.
"People saying that coal is bad and natural gas is much better are only looking at a small part of the picture," said Wigley, who is also an adjunct professor at the University of Adelaide in Australia.
His research, based on simulation data, incorporated effects from sulfur particles, a byproduct of coal combustion, and methane leaks. Methane is a major component of natural gas and can leak from coal and gas mining operations. The gas is also a substantially more potent greenhouse gas than carbon dioxide, said Wigley.
Sulfur emissions, on the other hand, can shield sunlight, which complicates the climate analysis. "It's an interesting sort of Catch-22," said Wigley. "By reducing the amount of coal, we reduce the cooling effect of the aerosols."
In the simulation, half of all coal power plants were shut down and switched to natural gas based on midrange trend estimates from the U.S. Climate Change Science Program. Wigley also assumed no energy policy changes from current standards, like renewable energy incentives or carbon taxes.
The results showed that global temperatures would actually go up by less than 1 degree Celsius over the next 40 years, followed by a decline relative to current temperature projections. Wigley said these results indicate that there are many factors at play and that fighting climate change shouldn't focus on any one element.
"Anybody that's in climate science knows that there are a lot of different forcing agents involved in climate," said Wigley. "It's not just a CO2 issue; it's a climate mitigation issue."
Not a silver bullet
Wigley also said that sulfur emissions, especially sulfur dioxide, should not be considered as a strategy for combating global temperature increases, since the short-term harms outweigh any long-term benefits. Sulfur dioxide is a major component of particulate pollution, can cause heart and lung problems, and forms acid rain.
For Wigley, the proper course of action is not yet clear, since he cannot determine if the change in the emissions profile between coal and natural gas is worth the expenditure. "That would require a regional economic analysis for damages from acid rain and carbon dioxide and the benefits of reduced climate change," said Wigley. "It's tough for decisionmakers."
Other researchers were not as ambivalent: Robert Howarth, the David R. Atkinson professor of ecology and environmental biology at Cornell University, published a paper in April in Climatic Change Letters that he described as "pessimistic" about the switch from coal to gas. "I believe this idea has been over-hyped by industry as well as many in government and some in NGOs," said Howarth in an email. "It's time to move on truly green energy technologies -- solar, wind -- and to place a much greater emphasis on energy efficiency."
However, industry groups, like America's Natural Gas Alliance (ANGA), think otherwise. ANGA Vice President of Strategic Communications Dan Whitten said that his group is still studying the report's findings, but noted that natural gas has clear benefits. "It is the established scientific consensus that whether we are talking about carbon dioxide, sulfur dioxide, nitrogen oxide, mercury or particulate matter, natural gas is a cleaner energy choice that can help improve air quality in communities across our country," said Whitten.