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Subsea methane release documented
You know that theory about how methane's trapped under permafrost and it could be a Bad Thing if it was to be released? Well, it looks like it's happening.
Orjan Gustafsson of Stockholm University, in an Independent article: "An extensive area of intense methane release was found [in the Laptev Sea, North of Siberia]. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These 'methane chimneys' were documented on echo sounder and with seismic [instruments]."
"The conventional thought has been that the permafrost 'lid' on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place. The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leak methane... The permafrost now has small holes. We have found elevated levels of methane above the water surface and even more in the water just below. It is obvious that the source is the seabed."
Oh, crap.
Orjan Gustafsson of Stockholm University, in an Independent article: "An extensive area of intense methane release was found [in the Laptev Sea, North of Siberia]. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These 'methane chimneys' were documented on echo sounder and with seismic [instruments]."
"The conventional thought has been that the permafrost 'lid' on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place. The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leak methane... The permafrost now has small holes. We have found elevated levels of methane above the water surface and even more in the water just below. It is obvious that the source is the seabed."
Oh, crap.
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What does it break down into?
or do you mean absorbed (plants (very limited, that's a cycle), or ocean (acid time)).
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Some methane will be broken down by the activity of free radicals. But while oxidation by the hydroxyl radical is the main sink, it's not the only one. Methane is also taken up by soils.
When you're talking about timescales of effect as a greenhouse gas, I wouldn't have thought the method of removal from the atmospheric reservoir was of major concern.
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Here's some joy: the last comparable period of sudden warming, which may have been down to a methane-release event, took place so rapidly that the geological record can't resolve a timescale (the resolution's about 1000 years). And it took 100,000 years to settle back down again.
'Welcome to the Hot Earth: Home of modern Humanity. Remember our old combustion-using forebears in the Age of Waste? Back then, they had something called "snow"...'
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<plant absorbs CO2, plant dies, bacterial action releases CO2>
Now we are releasing massive amounts of CO2 taken out of the cycle millions of years ago. I'm not sure that that CO2 will be taken back out of the atmosphere. It'll join the cycle, but in order for the CO2 levels to drop back down again, there has to be a mechanism of removal above and beyond the normal cycling.
A massive increase in biomass would do that, but I've not seen any sensible plans for how to get that to happen and I can't see it happening naturally.
Methane is different...that can get broken down relatively easily to more stable forms (CO2 + H2O). So for the medium term (beyond the 9 - 15 you mention), I consider that to be adding to the CO2 pool, rather than a more long term methane pool.
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The immediate effect of this is increased levels of water vapour in the troposphere, which has a negative impact on the ozone layer. After a series of further reactions, IIRC, it becomes an aldehyde, but I'd have to get my environmental chemistry book out when I get home to check. i know it's not quite as simple as CH4 + OH —> CO2 + H2O.
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there may be lots of intermediate steps, but that'll probably be what happens overall (if an atmospheric process).
I suppose there could be a bacterial process, in which case it might get incorporated into the hydrocarbons of the bacteria. But eventually the bateria will die or get eaten and it'll go to CO2 eventually as that breaks down.
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I don't have the entirety of the various steps and loops in the carbon cycle in my head, I'm afraid, but I'd be very relucant to come to any conclusions based on an atmospheric methane timescale of 9-15 years and "eventually it turns into carbon dioxide".
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If you want an increase in biomass then how much of that would get taken up by increased tree growth as the warm belts move north? Probably not much, almost certainly not enough (and frankly we should stop cutting down tropical rainforests as well) but does that make any sense
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It's an awful lot of carbon that's being chucked into the air at the moment.
I can't see that CO2 has a finite life span in the atmosphere. Certainly I've not heard of a mechanism that will take it out in anything like a suitable timespan.
It took a very very long time for the oil and coal to be laid down.
Growing trees and burying them seems like a lot of effort.
Lets hope for fusion power, lots of CO2 fixing equipment and filling the holes we've just dug back in.
flitljm thought plants would take up the strain over a longish period...but this suggests maybe not:
http://news.bbc.co.uk/1/hi/sci/tech/7620921.stm
though I suppose that is just for plants being out of the zone they like. They'll migrate with the temperature they like eventually.
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The last time we had a major temperature spike, the slack was taken up over a period of tens of thousands of years...
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The problem is that currently we are increasing CO2 emissions while not increasing (and in some cases decreasing) carbon sinks. Natural cycles are all about balance. Life itself is a delicate but dynamic balance. You can't reduce the Earth to a simple series of stoichiometric equations. If that were the case you might as well start hurtling trees into space because they'll become CO2 as well, eventually. So will you. So will I. We could bury 30% of the world's population in a large concrete bunker and that would sequester a good amount of carbon but I don't think that would be politically acceptable.
On human scales no, it won't happen in time. But humans are another species subject to the same Malthusian concepts of resource crisis as every other. When things get really bad mortality will increase. Under environmental pressure there will be cultural clashes because in a resource crisis every animal becomes territorial and humans are very cultural. War, disease, famine, financial stress, drought, flooding and civil unrest will all contribute. Doesn't matter whether we build fusion reactors and develop carbon sinks. We won't do that in time either. We really don't have very long. In a chaotic system all it takes is something to trigger phase change and then all we can do is try to survive until another tipping point is reached.
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because if that's the case, then we don't need to worry too much. Get hot, wait 2-3 generations, cool down again.
I just don't think that is the case.
>>You can't reduce the Earth to a simple series of stoichiometric equations
Isn't that the whole greenhouse gas argument?
Dig up buried hydrocarbons, burn them to release CO2, V.BAD.
(CxH2x+2 + O2 -> CO2 + H2O)
Burying people isn't sensible, but putting bodies or trees back down the mine shafts and sealing them would remove the CO2 that we are digging up I suppose. See my previous comment about fusion, CO2 extractors and mineshafts.
1) We are going to burn all the hydrocarbons we can lay our grubby little hands on.
2) The CO2 will stay around forever (for all practical purposes......hundreds of generations).
We either learn to live with the consequences (not easy), or do something to remove the CO2 (not easy).
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The main reason for payment to protect tropical forest is that land use change, primarily deforestation, accounts for around 18 to 25% (or maybe even more if soil carbon is properly factored in) of current CO2-equivalent greenhouse gas emissions. Reducing deforestation is not just a relatively cheap way of reducing emissions, it has other benefits (you get to keep the forest goods and services) that don't emerge from other solutions. But in all honesty, we need every method of reducing emissions we can get. We can't just sit back and go 'oh, it's too late'.
That said, marine biologists are -very- wary of iron seeding, plankton blooms being generally bad for other sea life. Its unclear whether its effective in carbon terms, but some private co's already marketing credits for small-scale efforts.
Temperature experiments - plants will only take up more CO2 if conditions for growth are improving - longer growing season in temperate realms, and better average weather. Those seem to have been grassland plants getting hotter and drier. Response doesn't hold for tropical plants getting warmer and wetter (common projection for W Amazon), which as an ecosystem (not all species) should encourage growth.
Probably, tropical forests have been putting on biomass to date, taking advantage of a bit more warmth and CO2, but the thinking seems to be that this will peak shortly. There's a live debate around these trends (e.g. http://www.citeulike.org/user/Flit/article/2507850).
Boreal forests are projected to spread, increasing carbon storage and possibly protecting peat bogs from temperature-induced degradation, but changing the albedo because forests hold snow for a shorter period. Considering only the albedo versus carbon uptake balance suggests that boreal spread will have a net warming effect (http://www.citeulike.org/user/Flit/article/1281557), but afaik no-one has done the sums for the soil carbon.
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