Accounting Trick on Methane Is Deadly for the Climate

It should come as no surprise that politicians use accounting tricks to make us think their paltry efforts are worth a damn. A widespread and well established trick is to dilute on paper the annual impact of climate pollution by spreading it over 100 years.

The likely next Secretary of Energy, Ernest Moniz, has supported but is now undecided about liquid natural gas (LNG) terminals to export fracked gas. But it's no secret that this administration has supported gas. The State Department's 'Global Shale Gas Initiative' is an example of efforts by this government to promote US shale gas globally. The administration often justifies its promotion of gas as a climate benefit -- doublespeak in effect. They can do this only because they use the 100-year accounting trick to assess the impact of methane on climate.

Scientists like Dr. Drew Shindell of NASA promote the 20 year time horizon. The lifetime of emitted methane in the atmosphere is about eight years. It is contagion to reference the 100-year calculation provided by the Intergovernmental Panel on Climate Change (IPCC) in 1995. But the IPCC also provided a reference for the 20-year time horizon, which has been largely ignored. This a horrible mistake for three big reasons.

First, if we don't make serious progress on reducing climate pollution within the decade, what we do afterward will be moot. The political and scientific goal, depressingly dated, is to avoid surpassing a two degree Celsius rise of global average temperature, which requires the atmospheric concentration of greenhouse gas not exceed 450 parts per million. This is supposed to give us about a 50 percent chance of avoiding disaster, and it cannot happen without arresting the increase in global climate pollution by 2015. The utility of considering global warming potential over 100 years has long past.

Because of our destruction of carbon sinks like forests and production of greenhouse gases (GHGs), Earth has been warming steadily. We see melting glaciers and ice caps, and CO2 being absorbed by the ocean. Once the ice is gone, the darker colored ground and sea will absorb more of the sun's heat and warm the atmosphere more. Once the ocean has absorbed enough CO2, it will become a net emitter rather than absorber of CO2. The melting of ice caps and glaciers brings the release of trapped methane pockets and methane hydrates, which alone could spell global climactic disaster. These and other 'tipping points' predicted to come within the next decade or sooner, are momentum enough to facilitate global warming without further help from humans. This has been called 'runaway climate change.'

Climate impacts are happening now. Each year people die from more extreme weather causing more frequent flooding and heavy rains, more droughts and heat waves. Climate havoc on water resources and sea levels displaces millions of people and jeopardizes the existence of entire countries. Economic damages in the United States are tens of billions of dollars per year.

Second, there is no political climate goal for 100 years from now, nor would one even matter. A rigorous accounting of greenhouse gas emissions would measure the potency of pollutants based on a time line that is relevant to our policy goals, not to mention the lifetime of politicians. This government has a 2020 climate pollution target that was set around 2010.

Let's say I want to retire in 30 years with a certain amount of savings. If I divide my savings goal over 150 years, I'll be desperately short of my goal at retirement. The interaction of human-caused climate pollution and the atmosphere is of course much more complicated, but the principle is the same. Politicians seem to have the false impression we can make a balloon payment on climate policy some day.

Looking at CO2 alone, or with a 100-year time horizon for all GHGs, the U.S. would be on track to meeting the Obama administration's goal of 17 percent GHG reduction from 2005 levels. In fact, the Obama administration has made this claim in the international climate talks. But looking at CO2 alone is a farce. The United States is not at all on track to meet its 2020 goal.

Third, using the 100-year time horizon keeps us from prioritizing non-CO2 climate pollution. Because the 'potential warming' of other pollutants is measured in comparison to CO2, the longer the time horizon the more infatuated we become with CO2. But what if instead of 84 percent of the problem CO2 were only 61 percent of the problem? This is what happens when you just assess methane potency over 20 years in stead of 100. This says nothing to F gases, also increasing, which can be tens of thousands of times more powerful than CO2.

Methane is the number two greenhouse gas after carbon dioxide (CO2). EPA says methane is 21 times as potent as CO2, using the IPCC reference from 1995. But methane over 20 years, based on the most recent data from Dr. Shindell at NASA, is 105 times more powerful than CO2.

The second largest source of methane is so-called 'concentrated animal feeding operations,' a euphemism for factory farms keeping animals in grotesque conditions. This says nothing to climate pollution coming from producing feed, fertilizer, and razing land for crops, which makes animal agriculture between a fifth but more likely closer to half of anthropogenic climate pollution. Discounting methane potency must be one reason that agricultural emissions are exempted from every federal climate policy proposal.

The largest source of methane is oil and gas extraction, especially fracking - the only type of gas production projected to increase. Changing the math to a 20 year time horizon means 'natural' gas vehicles are a no-go for climate. The only chance that total life cycle GHGs might be significantly lower than coal in power plants is if it's not fracked shale gas and not turned into LNG. Because liquefaction requires such a massive amount of energy leading to a massive amount of emissions, the same may be said comparing LNG to using gasoline in cars.

That 'natural' gas is bad for the climate should be a side note, given the promise of renewables. If we don't get a handle on non-CO2 climate pollution, which requires using a 20-year (or even 10 year) time horizon, then climate policy accounting is doomed to be a facade at best.