Pushing Back Against the Methane Tipping Point
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(Here's one piece of mitigating information: it's unclear how long this methane leak has been happening, or the degree to which the measured methane levels exceeds previous amounts. If we're lucky, this is actually a status quo situation, and we still have time before we reach a tipping point. But basing our strategy on "if we're lucky" is not very wise.)
Because of this tipping point/feedback process, a runaway methane melt won't stop on its own. When I've written before about desperation as a driver for the rapid (and risky) implementation of geoengineering, this is precisely the scenario I had in mind. If this news holds up, and if it can be shown that the methane leak is actually increasing, then I believe that we are certain to engage in geoengineering, and probably will do so before we have enough good models and studies to suss out any unwanted consequences. We'd be faced with a choice between guaranteed catastrophe or terrible uncertainty.
We'd probably try every geoengineering option available in the event of a methane runaway, but the one that most people would focus on would be the temperature management strategies: stratospheric sulfate injection, seawater cloud brightening, and (unlikely to happen but certain to get a lot of media attention) orbiting reflectors. But there's one more method we should consider. Understanding its potential requires a bit of science talk.
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These are pretty much the only two natural methane "sinks." There are a few small-scale human processes that can make use of methane (for the production of methanol for fuel, for example) and function as artificial sinks, but such efforts would be hard-pressed to capture methane released across two million square kilometers. So here's where we start to think big.
Both of the natural processes are, in principle, amenable to human intervention. The oxidation of methane into CO2 and water is a well-understood phenomenon, and relies on the presence of OH (hydroxyl radical); upwards of 90% of lower atmosphere methane is oxidized through this process (PDF). But OH is something of a problem chemical, in that it's also a key oxidation agent for many atmospheric pollutants, such as carbon monoxide and NOx. Although we could produce OH to enhance the natural chemical oxidation process, the side-effects of pumping enough OH into the atmosphere to oxidize all of that methane would be unpredictable, but almost certainly quite bad.
So what about methanotrophic bacteria? Such bacteria have long been recognized in freshwater areas and soil, and have had limited use in bioremediation efforts. Methanotrophic Archaea -- similar to bacteria, but a wholly different kingdom of organism -- were recently identified in the oceans; research suggests that methanotrophic Archaea may be responsible for the oxidation of up to 80% of the methane in the oceans. Methanotrophic microbes can also be temperature extremophiles, as they were among the various species found after the Larsen B ice shelf collapsed.
We recently began to learn much more about how methanotrophic bacteria function, as a team from the Institute for Genomic Research sequenced the genome of the methanotroph Methylococcus capsulatus. The scientists discovered that Methylococcus has the genomic capacity to adapt to a far wider set of environments than it is currently found in. They also looked at the possibility of enhancing the microbe's ability to oxidize methane, although admittedly for purposes other than straight methane consumption.
So here's the proposal: we need to deploy methanotrophic microbes at the East Siberian Ice Shelf. Methanotrophic Archaea appears to be best-suited for this task, but we don't know as much about them as we do about bacteria. If we need to modify the microbes (to consume methane more quickly, for example), we may need to work on Methylococcus bacteria, making them viable in extremely cold seawater. I suspect that working with the Archaea will probably be sufficient, but it's important to think ahead about different pathways. Either way, we should consider just how we could make use of methanotrophs to avoid a methane-melt disaster. Given the size of the region, we'll need lots of them, but that's one advantage of biology over straight chemistry: the methanotrophs would be reproducing themselves.
We need to be aware of possible unintended consequences, but at this point, it's not clear how additional methanotrophs would pose a larger risk; moreover, a mass of methanotrophic organisms would undoubtedly be helpful for reducing overall atmospheric methane beyond the Siberian release. Nonetheless, there are some crucial questions we need to answer before we could consider deploying natural or GMO methanotrophs:
# Is it physically possible? Could a sufficient number of methane-eating bacteria even be produced to counter a fast release of methane from the Siberian ice shelf?
# Is it biologically possible? Would methanotrophic Archaea survive in the Siberian ocean? Could a species of methanotrophic bacteria be engineered to be able to do so (as well as consume large quantities of methane)?
# What are the unrecognized risks? What are we missing in an initial risk analysis? Saying "we don't know the risks" doesn't, in and of itself, mean "we should not attempt this," it means "we need to do more research." Clearly, if the risks from enhancing the methane consumption and environmental adaptation capacities of a methanotroph could lead (through species-hopping genes or simple mutation) to even harder-to-manage problems than gigatons of atmospheric methane, this isn't an option. Boosting OH levels in the region would be the fallback position, as we have more experience with managing CO and NOx pollutants.
If the frozen methane in the Siberian ocean is melting faster, our options are extremely limited. We'd no longer be in a position to stop the melting, even by ceasing all greenhouse gas production today; the temperature increases we're seeing now are the results of greenhouse gases put into the atmosphere decades ago. And when methane melts, it appears to do so quickly -- there are signs that past methane clathrate events took less than a human lifetime.
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http://www.openthefuture.com/2010/03/pushing_back_against_the_metha.html
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