It’s only Wednesday and it’s already been a busy week on the issue of methane, a greenhouse gas that’s like carbon on steroids and is released extensively in the production of fossil fuels:
- There’s been ongoing coverage of our court victory last Friday overturning Arch Coal’s plans to expand its West Elk mine and in the process vent massive amounts of methane. That ruling invalidated a U.S. Forest Service and Bureau of Land Management approval of Arch’s plans on the basis that the costs of carbon pollution, including the costs of venting methane gas, were ignored, a big victory for the climate.
- On Monday, WildEarth Guardians submitted comments to the U.S. Bureau of Land Management on their proposal to finally start doing something about coal mine methane waste. The driver for this proposal has been the unchecked release of millions of tons of methane from underground coal mines in western Colorado, including at Arch’s West Elk mine (which I’ve previously blogged on), as well as President Obama’s call for cuts in methane emissions.
- And this week, a new study published in the Proceedings of the National Academy of Sciences found that newer gas wells being drilled into Pennsylvania’s Marcellus shale are leaking more methane than wells drilled into other formations. The study has major implications for shale oil and gas drilling and fracking across the nation, which is fast taking hold as the predominant form of oil and gas development. Indeed, we just commented this week on the Bureau of Land Management’s plans to allow 5,000 wells to be drilled into the Niobrara shale formation of eastern Wyoming.
Methane venting well at Arch Coal’s West Elk mine in western Colorado (click to see more pictures of what methane venting at coal mines looks like, including this video of methane venting in action)
There’s a lot going on around methane, but what’s disturbingly not being discussed is how the U.S. Environmental Protection Agency (and apparently other federal agencies, for that matter) are downplaying, if not covering up, the climate impacts of methane emissions.
Certainly, everybody recognizes that methane is a potent greenhouse gas, but what seems to be obfuscated is exactly how potent it is.
The measure of a greenhouse gases potency is also called its global warming potential. In the case of methane, the Environmental Protection Agency has for many years universally presumed a global warming potential of 21, meaning that for one part of methane equals 21 parts of carbon dioxide. But studies are consistently confirming that this estimate is too low, particularly when assessing the short-term climate impacts of methane emissions.
In fact, while studies are finding that over a 100-year period, the global warming potential of methane is more than 30 times that of carbon dioxide, they’re finding that in the short-term, methane may be as much as 105 times more potent than carbon as a greenhouse gas.
More recently, the Intergovernmental Panel on Climate Change (often referred to as the IPCC), probably the most authoritative (even if somewhat cautious) scientific body that is synthesizing climate information for policymakers and the public, reported methane global warming potentials under two scenarios: the first, where climate carbon feedback is not accounted for the second, where it is. The climate-carbon feedback factor refers to the fact that as carbon creates more warming, more greenhouse gas emissions are released. For example, as permafrost melts, more methane is released from Arctic tundra.
Taking into account climate-carbon feedback (which is more reasonable and accurate given the very real feedback impacts of greenhouse gas-fueled warming), the IPCC reported in their most recent synthesis of climate science that methane’s global warming potential is 34 over a 100-year period and 86 over a 20-year period (you can download their report at climatechange2013.org at p. 714). Below is the table showing the IPCC’s reported global warming potentials.
|Global Warming Potential||Over 100 Years||Over 20 Years|
|Without Climate-Carbon Feedback||
|With Climate-Carbon Feedback||
In spite of these findings, the Environmental Protection Agency continues to assume that methane’s potency is only 21 times that of carbon dioxide.
For instance, in the agency’s latest inventory of greenhouse gas emissions and sinks in the United States, which was released in April and presents 2012 data, they rely on a global warming potential of 21 (see their Executive Summary at p. ES-3). In doing so, they report that coal mines and oil and gas operations (the fourth and first largest sources of methane in the U.S., respectively) release the equivalent of 222 million metric tons of carbon dioxide (total of 10.57 million metric tons of methane).
Yet, based on a global warming potential of 86, total carbon dioxide emissions due to methane from coal mines and oil and gas operations is actually more than 900 million metric tons, a more than four-fold difference.
The table below shows the differences between EPA’s estimate of carbon dioxide equivalent emissions from coal mines and oil and gas operations, based on the outdated global warming potential of 21, and estimates based on the IPCC’s global warming potential factors.
Methane and carbon dioxide equivalent emissions (in million metric tons) from oil and gas operations and coal mines, based on EPA’s 2012 inventory of greenhouse gas emissions and sinks, released in April 2014, and IPCC global warming potential factors.
What this shows is that the climate impacts of methane are being significantly underestimated, in turn giving the impression that methane emissions from coal mines and oil and gas sources are not significant sources of carbon. In fact, just based on methane along, this data shows that oil and gas and coal mines are the fourth and fifth largest sources of carbon dioxide emissions in the U.S., right behind power plants, transportation, and industrial fossil fuel combustion.
Certainly, the Environmental Protection Agency has not outright discounted the significance of methane emissions from oil and gas operations, but they have refused to acknowledge that methane from coal mines is worthy of any agency attention.
And although the agency last fall officially raised the global warming potential of methane from 21 to 25, this is a far cry from reflecting the real short-term climate impacts of unchecked methane emissions. Furthermore, in doing so, the agency rejected establishing a global warming potential based on a 20-year timeframe, essentially turning its back on the fact that methane’s climate impacts are more significant over the short-term, rather than the long-term.
By downplaying the climate impacts of methane, the Environmental Protection Agency is undermining the urgency that should be driving efforts to cut emissions of this potent greenhouse gas. The result is that other federal agencies, the Bureau of Land Management notable among them, continue to drag their feet in acknowledging the need for methane reductions and the cost of delaying action.
With President Obama himself calling for methane cuts nationwide, it’s critical that the Environmental Protection Agency get it right in curbing this potent climate threat.
Categories: Climate + Energy