Abstract

Although the sudden high rate Arctic methane increase at Svalbard in late 2010 data set applies to only a short time interval, similar sudden methane concentration peaks also occur at Barrow point and the effects of a major methane build-up has been observed using all the major scientific observation systems. Giant fountains/torches/plumes of methane entering the atmosphere up to 1 km across have been seen on the East Siberian Shelf. This methane eruption data is so consistent and aerially extensive that when combined with methane gas warming potentials, Permian extinction event temperatures and methane lifetime data it paints a frightening picture of the beginning of the now uncontrollable global warming induced destabilization of the subsea Arctic methane hydrates on the shelf and slope which started in late 2010. This process of methane release will accelerate exponentially, release huge quantities of methane into the atmosphere and lead to the demise of all life on earth before the middle of this century.

OK, this seems pretty fucking bad, but I'm not sure how I'd evaluate its likely veracity. Anyone know of or can give a second opinion?

Could there be a methane runaway feedback?.

The “runaway greenhouse effect” that planetary scientists and climatologists usually call by that name involves water vapor. A runaway greenhouse effect involving methane release (such as invoked here) is conceptually possible, but to get a spike of methane concentration in the air it would have to released more quickly than the 10-year lifetime of methane in the atmosphere. Otherwise what you’re talking about is elevated methane concentrations, reflecting the increased source, plus the radiative forcing of that accumulating CO2. It wouldn’t be a methane runaway greenhouse effect, it would be more akin to any other carbon release as CO2 to the atmosphere. This sounds like semantics, but it puts the methane system into the context of the CO2 system, where it belongs and where we can scale it.

So maybe by the end of the century in some reasonable scenario, perhaps 2000 Gton C could be released by human activity under some sort of business-as-usual scenario, and another 1000 Gton C could come from soil and methane hydrate release, as a worst case. We set up a model of the methane runaway greenhouse effect scenario, in which the methane hydrate inventory in the ocean responds to changing ocean temperature on some time scale, and the temperature responds to greenhouse gas concentrations in the air with another time scale (of about a millennium) (Archer and Buffett, 2005). If the hydrates released too much carbon, say two carbons from hydrates for every one carbon from fossil fuels, on a time scale that was too fast (say 1000 years instead of 10,000 years), the system could run away in the CO2 greenhouse mode described above. It wouldn’t matter too much if the carbon reached the atmosphere as methane or if it just oxidized to CO2 in the ocean and then partially degassed into the atmosphere a few centuries later.

The fact that the ice core records do not seem full of methane spikes due to high-latitude sources makes it seem like the real world is not as sensitive as we were able to set the model up to be. This is where my guess about a worst-case 1000 Gton from hydrates after 2000 Gton C from fossil fuels in the last paragraph comes from.

On the other hand, the deep ocean could ultimately (after a thousand years or so) warm up by several degrees in a business-as-usual scenario, which would make it warmer than it has been in millions of years. Since it takes millions of years to grow the hydrates, they have had time to grow in response to Earth’s relative cold of the past 10 million years or so. Also, the climate forcing from CO2 release is stronger now than it was millions of years ago when CO2 levels were higher, because of the band saturation effect of CO2 as a greenhouse gas. In short, if there was ever a good time to provoke a hydrate meltdown it would be now. But “now” in a geological sense, over thousands of years in the future, not really “now” in a human sense. The methane hydrates in the ocean, in cahoots with permafrost peats (which never get enough respect), could be a significant multiplier of the long tail of the CO2, but will probably not be a huge player in climate change in the coming century.

This process of methane release will accelerate exponentially, release huge quantities of methane into the atmosphere and lead to the demise of all life on earth before the middle of this century.

To actually sterilize the planet you would literally need to melt the entire solid crust into lava so that is not going to happen.

Oddly enough, that is sort of like what happened in Siberia during the time of the Permian extinction, resulting in the Siberian Traps. OK, it wasn't the whole world, but a substantial area did get covered in molten rock.