Sustained Outrage

More questions about climate benefits of gas switch

We’ve written before about the developing science regarding the potential global warming benefits of a switch from coal to natural gas (see here, here and here).

And now, we have a new paper out in the journal Climate Change Letters that projects a switch to gas won’t have an appreciable impact on global warming, at least not in the next few decades.

Tom Wigley, a senior scientist at the National Center for Atmospheric Research, concluded in the paper:

In summary, our results show that the substitution of gas for coal as an energy source results in increased rather than decreased global warming for many decades — out to the mid 22nd century for the 10% leakage case.

In a news release, the National Center for Atmospheric Research explained:

The burning of coal releases more carbon dioxide than other fossil fuels, as well as comparatively high levels of other pollutants, including sulfur dioxide, nitrogen oxides, and particles such as ash. Since natural gas emits lower levels of these pollutants, some energy experts have proposed greater reliance on that fuel source as a way to slow down global warming and reduce the impacts of energy use on the environment.

But the effects of natural gas on climate change have been difficult to calculate. Recent studies have come to conflicting conclusions about whether a shift to natural gas would significantly slow the rate of climate change, in part because of uncertainty about the extent of methane leaks.

Wigley’s new study attempts to take a more comprehensive look at the issue by incorporating the cooling effects of sulfur particles associated with coal burning and by analyzing the complex climatic influences of methane, which affects other atmospheric gases such as ozone and water vapor.

It continues:

By running a series of computer simulations, Wigley found that a 50 percent reduction in coal and a corresponding increase in natural gas use would lead to a slight increase in worldwide warming for the next 40 years of about 0.1 degree Fahrenheit (less than 0.1 degree Celsius). The reliance on natural gas could then gradually reduce the rate of global warming, but temperatures would drop by only a small amount compared to the 5.4 degrees F (3 degrees C) of warming projected by 2100 under current energy trends.

If the rate of methane leaks from natural gas could be held to around 2 percent, for example, the study indicates that warming would be reduced by less than 0.2 degrees F (about 0.1 degree C) by 2100. The reduction in warming would be more pronounced in a hypothetical scenario of zero leaks, which would result in a reduction of warming by 2100 of about 0.2-0.3 degrees F (0.1-0.2 degrees C). But in a high leakage rate scenario of 10 percent, global warming would not be reduced until 2140.

Wigley said:

Whatever the methane leakage rate, you can’t get away from the additional warming that will occur initially because, by not burning coal, you’re not having the cooling effect of sulfates and other particles. This particle effect is a double-edged sword because reducing them is a good thing in terms of lessening air pollution and acid rain. But the paradox is when we clean up these particles, it slows down efforts to reduce global warming.

There’s more coverage of this study from the L.A. Times and the Boulder Daily Camera.