Quick: Which is worse, a carjacking or a rape?
I know what you're thinking, but suppose the carjacking involved a gun, whereas the rape was "just" statutory rape between a sixteen-year-old and her nineteen-year-old boyfriend?
To be fair, though, neither of these examples is probably quite representative of the "typical" carjacking or rape. Perhaps we ought to assess the badness of each act based upon a weighed average of the typical circumstances of the two crimes, respectively, and only then give our opinion about which is "worse," per se. Then again, it is possible that the social stigma that has historically been associated with the victims of rape causes that crime to be systematically underreported, leading to a biased sample.
At this point we could do some philosophical heavy lifting involving definitions, sources of data, and standards of badness, all as a preface to an open-ended debate with other people who made different assumptions or preferred other data sets. Or, just putting it out there, we could ask ourselves why the fuck we care.
As the astute reader can probably discern, I'm losing interest in the question of whether shale gas or coal is worse for the climate. This is an unfamiliar experience for us here at IT; more typically, we find ourselves worrying the bone of a topic whilst other, more responsible commentators have long since satisfied themselves that there's not an atom of meat left to scavenge (can you say, Scott Armstrong's climate "bet"?)
But I'm about ready to be done with this one, and the reasons are fairly simple:
1. The answer is heavily dependent on the initial assumptions you chose. Both the facts (the leak rate) and the value judgments (how far into the future should we look to compare the effects of CO2 and methane ) remain hotly disputed. It is also laughably easy to stack the deck by comparing new natural gas to old coal, or old natural gas to new coal, or heating capacity vs electrical generation, none of which choices are clearly right or wrong and all of which, given a large energy sector and enough time, will describe some set of power plants, somewhere.
2. Even if we could reach a final a definitive answer to the question, we would still be left with the reality than coal has a bunch of other negative externalities, most crucially, the particulate pollution kills people. As vitally important as climate change is, you can't just pretend all the other costly, deadly, and environmentally destructive consequences of coal mining and coal burning don't exist.
3. Like a lot of questions that suck up time and energy in the climate debate, this one fails to inform the discussion of the only question which, in the final analysis, matters at all: Will our society and the global civilization to which it belongs succeed in undertaking collective political action (commensurate with scale of the challenge) to limit global warming and abort the Business as Usual scenario?
If we will, there are numerous tools and technologies close at hand to speed our transition, which might or might not include some shale gas. If we won't, if we are determined to rely on blind chance in the form of a distorted profit motive coupled with an unchecked tragedy of the commons to deliver us, we will bring down devastating climate change upon ourselves, and whether the cheap shale gas that energy companies pried out of the ground purely in the name of corporate profits happened to be somewhat better or somewhat worse for the climate than coal will be the definition of irrelevance.
1) So what's the leak rate, really? Very recently, the EPA estimated 2.3%, but this was revised downward to 1.4%. On the other hand, direct measurements of leakage from gas fields often come in quite a bit higher, as in the recent study that found leakage from 6.2% to 11.7%. This followed another study from 2012 that found leakage rates of 4% at a field near Denver.
When your estimates of a quantity from various credible sources differ by an order of magnitude, I think it's fair to suggest that we do not have a firm grasp on the final number.
Note, too, that it is not just the wells that leak. The downstream infrastructure is full of leaks as well, and this may account for a third of the estimated fugitive emissions.
This naturally raises the question: couldn't we fix that leaky infrastructure if we wanted to? (Yes, we could.) For that matter, couldn't we strictly regulate and monitor shale gas developments to force companies to keep their fugitive emissions low, or risk hefty fines? (Seems to discourage oil spills.) And might that alter the calculus of whether the substitution of gas for coal brings important climate benefits? (Of course it could.)
This is why I say the central question is not which energy source is "better," but whether or not we have the will to take collective political action to make the situation better.
2) The latest marker in this debate was laid down by Raymond Pierrehumbert, a climate giant by any definition, but one who in this case, in my opinion, has not got things quite right. He says:
The important thing to understand is that essentially all of the climate effects of methane emissions disappear within 20 years of cessation of emissions; in this sense, the climate harm caused by methane leakage is reversible. In contrast, CO2 accumulates in the atmosphere, ratcheting up the temperature irreversibly, at least out to several millennia. Therefore, if switching to natural gas from coal reduces the amount of CO2 you emit, you can tolerate quite a large amount of leakage and still come out ahead, because the warming caused by the leakage will go away quickly once you eventually stop using natural gas (and other fossil fuels), whereas the warming you would get from all the extra CO2 you’d pump out if you stuck with coal would stay around forever.One can quibble with some of Pierrehumbert's facts here; the breakdown of methane in twenty years or so depends on how much of the stuff is in the atmosphere to begin with; some of the reactions are subject to saturation kinetics. These can extend the life of methane in the atmosphere by a factor of three or more, albeit at concentrations far higher than today's.
But the important problem here is logical, not factual. Pierrehumbert's absolutely right that looking at the earth in a thousands years or so, the amount of methane that leaks today is not going to have any influence on the amount of radiative forcing the earth is experiencing. Whereas a significant bit of the CO2 released today will still by present in the atmosphere, warming the planet every minute of every day right out through the year 3,000 anno domini and beyond.
The problem, as I've said, is with the logic. When you define your vantage point as "thousands of years in the future" or even hundreds of years, you can discount the radiative effects of methane today. But from that vantage point, looking down on oceans that have swallowed dozens of the world's great cities, in the aftermath of wars over water and food, with three-quarters of all mammals extinct, from that vantage point, all fossil fuel burning looks like a crime against humanity. If future Ray from the year 3,000 gets a vote, he may very well not give two straws for the methane leaks, but he will veto the carbon dioxide released by burning shale gas.
This is perhaps a more subtle point than is usually to be found on this frankly pugilistic blog, so let me restate it in the form of an analogy:
You are in the emergency room suffering with some abdominal pain. Your doctor comes in to share the good news that all your tests are negative and you will be going home, after one more (ludicrously expensive) CT scan. When you ask why this is needed, she tells you "Oh, it's going to be a big help in a couple of days, when you come back in with overwhelming sepsis on the brink of death."The proposed CT scan makes no sense because you either are or are not sick: it makes no sense to take some actions based on the idea that you are fine (discharging you home) and others based on the belief that you are extremely ill (an expensive scan after your other tests were negative.)
Similarly, if you are the kind of person who thinks the state of things in the year 3,000 is critically important, then you are welcome to be indifferent to methane leaks, but by the same token, no fossil fuel burning should be even a little bit acceptable to you -- you, the far-future person, suffering from the effects of our stupid and thoughtless abuse of our shared life support system even after we knew the likely consequences -- future you will look at gas' lesser amount of CO2 per Kwh of electricity in the way we, in 2013, look at slave owners that only whipped their slaves after a fair and impartial hearing. That is, far-future you will recognize one of these things as theoretically more awful than the other, but regard the activity as a whole as so morally repugnant as to make the distinction academic, at best.