Methane in the Twilight Zone (Second Episode)

Methane in the Twilight Zone (Second Episode)
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The most important paper on climate change in quite a while was published two days ago in Science (Shindell et al, 2012: read about it here). But sorry, folks, we don't have time to discuss it now. We've got to get back down -- way down, into the twilight zone, where the methane is leaking. Things started to get weird as we began our descent last episode.

Now, we all know, the darkest twilight is found in the human mind. Last week, David Archer -- an important climate scientist and major contributor to the highly authoritative blog RealClimate -- suddenly jumped with a big splash into the recently spreading methane swamp, posting there his "Much Ado About Methane." Archer is a brilliant scientist and has contributed important work to understanding long-term climate impacts (showing that a significant amount of the carbon we put into the atmosphere as carbon dioxide will remain there for more than 100,000 years). Here, well, he's got an original theme! Tragi-comic, yet with Zen-like austerity, too.

The central theme of Archer's play, twisted like the plot of a Shakespearean comedy, is this: since methane is oxidized in the atmosphere by photochemical reactions to carbon dioxide (and water vapor), and the carbon in that carbon dioxide essentially lasts forever, bouncing around for 100,000 years, even a very large excursion of methane doesn't really make methane important (it plays the central character here of 'Nothing'), because the carbon dioxide the methane oxidizes to has about as great an impact as the methane, when integrated over 100,000 years! We've all heard of the 7th generation principle, but the "7,000th generation principle" is perhaps a bit overdone, especially when expressed along with almost Strangelove-like indifference to more immediate and present dangers we potentially could face, like, now.

Archer, in his follow-up a few days later, said that major arctic methane releases, whether chronic (like those discussed on the front page of the New York Times) or sudden, are no worse than "business-as-usual CO2." That certainly does not seem accurate when using more relevant time scales, although Archer has since posted a toy methane/carbon dioxide model, purporting to show that this holds true even for the current century. He posted the page of computer code, when I asked for further explanation, but there seems to be little in there except the lifetimes and instantaneous forcings (radiative forcing is a measure of changes in the planet's energy balance) of the gases. But gas forcings alone are of little use -- you at least need to use the net forcings of the processes producing the gases (i.e., including co-emitted aerosols), or it has little to do with the real world experience of those emissions in the time frame at hand. Things have gotten a little weird. Is this really real climate?

But even if Archer were right, that's still my point. James Hansen has written, and I hope that David Archer will read and ruminate:

If fossil fuel CO2 emissions continue to increase unabated, other climate forcings are relatively unimportant. However, this scenario is unlikely. Global warming is
becoming apparent. Efforts to slow GHG emissions and stabilize global climate
may increase. In this case, especially if the warming that constitutes 'danger' to
the planet is as small as we estimate, non-CO2 forcings become very important.

That is why for some of us -- assuming that humanity will make at least a moderate shift to a lower carbon economy (or all our 'Ados' will clearly lead the way to dusty Nothing) -- non-carbon dioxide emissions like methane, whether human-caused or leaking from the arctic, are of the utmost concern, as they could become the maker or breaker of our ability to keep the climate under control.

Archer's thinking makes sense, if you're not planning on doing anything about the climate. The more you are, the more his downgrading of leaking methane to 'Nothing' by taking an absurdly long view becomes quite weird. Does Archer really believe that in the year 5897, or even 58,970, for that matter, we still couldn't bury a little bit of our carbon, when there are myriad ways of doing so right now, if anyone were willing to pay for it? In this way, our carbon dioxide will not really have to last forever, if we can just make it through the multiple crises we are in, the most immediate of which some at Oxford have dubbed the "feedback crisis."

How bad is this "feedback crisis"? Make no mistake about it: building the XL pipeline, while terrible, doesn't necessitate "game over" for the climate, as James Hansen recently claimed, but if any single thing could make "game over," it is suddenly finding ourselves with a significant spiraling arctic methane feedback, with very large pulses to the atmosphere. Imagine a quick spike in temperatures, locally and then globally, the rapid loss of ice, the increased fires from peat and forest fires, the warmer ocean surface waters and loss of carbon sinks there. Who's even going to bother, amid whatever would be left of normalcy, with something as weak as the Copenhagen Accord's 50 percent cuts in global emissions (by 2050), if 50 Gt (gigatons) of methane have just come out, spread over a half decade, say, adding their powerful forcing (something like 100 years of carbon dioxide emissions all at once)? That's "game over." David Archer is, I believe, as wrong as wrong gets here. The biggest chunk of added radiative forcing since industrialization has come from carbon dioxide, of course, but we've still avoided feeling much of it, because it's been continuously masked by co-emitted aerosols. That's a rotten Faustian bargain, as Hansen said long ago, but Faustian bargains have a way of going on a long time! Masking aerosols will still be around. But when you add a big spike (say a 50 Gt release) of methane, there's no mask on this intruder -- believe me, you're going to notice him!

David Archer is brilliant and does wonderful work, so what is wrong? Ultimately, the problem here is a bias of time: just as spatially one can "not see the forest for the trees," so can one also "not see the minutes for the millennia." We're in a crisis, and crisis means compression of time. If businessmen wanting their cash get temporally near-sighted, climate scientists, lost in their graphs of millennia, get farsighted, forgetting that sometimes you have to duck bullets -- and they don't call it the 'methane gun hypothesis' for nothing! And that's one hypothesis you sure don't want to wait around and test! So, just this week you have seen both the best work in climate science telling you, "You can actually cool things down relatively quickly for now -- concentrate more on methane," and an entry point into the twilight zone of 'methane denialism,' RealClimate's comedy, "Much Ado About Methane." In my November post, I portrayed it as a methane fulcrum, or a methane forked road: either we cut our emissions right away, or we risk nature's. Either way, it's the methane, friends.

Unlike Michael Beard, the decadent fictional climate-change-invested physicist in Ian McEwan's novel Solar, David Archer has never visited the arctic. One might have expected a post expressing curiosity about the newest questions concerning arctic methane releases, which is what we are going to start investigating in the next episode. Instead, his tone suggested that all of those paying close attention to such findings must have been consulting their Mayan calendars. It is precisely such weird reactions in RealClimate and the New York Times, in fact, that made me want to find mine. Ah! Here it is! My God, January 2012's half over! The year's racing by, full tilt -- fasten your seatbelts, the car's swerving close to the guardrail, the chase is on, the views panoramic, the cliffs steep.

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