Runaway Global Warming - Closer that you think

vetusfirma

NO NO NO.....just kill the cows, talk about methane, then BBQ galore.

you can kill and eat the humans later cid.
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TheDude

MacG · Light Sweet Crude Joined: Jun 04, 2005 Posts: 1178

GregWatson · Heavy Crude Joined: Jun 07, 2008 Posts: 132

katkinkate · Last edited by katkinkate on Sun Jun 08, 2008 1:01 am; edited 1 time in total

Re the possibly imminant methane burp. You know that the reason why methane is normally such a tiny proportion of the atmosphere, is because of it's high reactivity to oxygen. Basically one methane molecule will be quickly 'burned' yielding a CO2 and 2 H2O molecules. That is, one methane molecule uses up 2 oxygen (O2) molecules.

I was wondering, how much danger is there of a big enough methane burp to significantly reduce the oxygen level in the atmosphere to dangerously low levels. Humans need at least 15% oxygen in each breath in order to live, probably a bit higher to allow for the work necessary to get food, water and shelter. Oxygen is now about 21%. So how much methane would it take to suck up 5-6% of the oxygen?
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"The ultimate goal of farming is not the growing of crops,
but the cultivation and perfection of human beings."
Masanobu Fukuoka

Cid_Yama · Last edited by Cid_Yama on Sun Jun 08, 2008 12:38 am; edited 1 time in total

In sum, there is no significant evidence of biological or ecological changes in the Permian that would have affected the level of atmospheric oxygen, with the possible exception of an extinction event about five million years before the end of the Permian (the end-Guadalupian extinction: Stanley and Yang, 1994; Racki, 2003). Lacking any compelling evidence for changes in those factors which would have affected atmospheric oxygen levels, therefore, the most reasonable assumption is that atmospheric oxygen levels nearing the end of the Permian were pretty much the same as at its start, and that it was the Permian extinction event itself which was responsible for the plummeting of those levels. If this reasoning is correct, then hydrogen sulfide releases to the atmosphere would have been one of the many effects of the end-Permian catastrophe (although a quite deadly one), rather than a cause of the catastrophe per se.

Despite these difficulties, the hydrogen sulfide release scenario prompts some further comments. First, once the end-Permian ocean had become largely anoxic (and in anoxic areas, devoid of aerobic organisms), it would have been quickly resettled by anaerobes such as the methanogens and sulfate-reducers (which produce hydrogen sulfide). Sulfate-reducers, not being quite as strict anaerobes as methanogens, would have expanded into areas where there were low concentrations of oxygen (highly dysoxic areas), from which methanogens would have been excluded. But even in fully anoxic areas, sulfate-reducers would have outcompeted methanogens for certain important nutrients (specifically for hydrogen molecules and acetate: Brock and Madigan, 1988), though some methanogens can use other, less plentiful nutrients. Consequently, the sulfate-reducers would have become the main inhabitants of the anoxic deep ocean, sharing it with more limited numbers of methanogens. No wonder sulfidic (euxinic) conditions developed in the Early Triassic ocean (see the discussion of the Black Sea, below, in the Early Triassic Aftermath section).

Second, because hydrogen sulfide readily combines with iron, it would have effectively scavenged iron from much of the ocean, combining with it and sending it to the bottom as iron pyrite (FeS¸2). Iron is an essential nutrient, and one which already exists in only limited quantities in the ocean. (That is why "iron fertilization" is being examined as a strategy for dealing with the atmosphere's excess carbon dioxide. Provided to phytoplankton, it creates "blooms" which, because the phytoplankton use carbon dioxide, helps reduce its presence in the air.) With iron availability already limited, marine organisms would have faced conditions of iron starvation once hydrogen sulfide became plentiful.

Third, it seems quite unlikely that no hydrogen sulfide would have escaped oceanic containment, because it escapes in places today despite our very well oxygenated ocean. Once in the atmosphere in significant quantities, hydrogen sulfide would have interacted with hydroxyl ions (OH^), and helped block the destruction of methane by those ions (that is, it would have increased the methane residence time), allowing faster, greater atmospheric warming. As the atmosphere's warmth penetrated the ocean, stratification would have increased (or been maintained), and the sulfate-reducers would have thrived. Thus, there could have been a kind of methane-hydrogen sulfide partnership, with each gas enhancing the presence of the other, until other factors (such as the drawdown of atmospheric carbon dioxide via increased weathering of silicate rocks) brought the era of the relationship to a close. Such a partnership may have also existed at other times of ocean anoxia, as indicated by significant negative sulfur isotope excursions: in the Early Cretaceous (120 to 100 million years ago: Paytan, 2004), and during the Paleocene-Eocene Thermal Maximum (55 million years ago: Paytan, 1998; Faul, 2005).

link

Lane sums up the situation at the end Permian as a hellish nightmare of a world gone awry, the pressures on organisms at that time being so great that many would not survive;

So with dangerously low atmospheric oxygen levels, ecosystems were compressed and fragmented. The deep oceans were largely uninhabitable. Land plants were dying back in the arid greenhouse climate, making food hard to come by. And then came the hammer blows of fate, the greatest volcanic outpourings in the history of our planet, releasing vast quantities of methane and carbon dioxide, raising global temperatures by 6 °C, and lifting the Strangelove conditions to the very surface.

Head for the hills and there’s no oxygen; stay on the shores and you risk breathing hydrogen sulphide. High carbon dioxide levels sabotage your respiratory pigments and choke you from within. Even if death doesn’t get you right away, you’re unlikely to have much spare energy for sex. Population sizes fall; so do body sizes. Even for those that survive the immediate toxicity, slow extinction was likely over a few generations — the blink of an eye in geological terms.

http://laelaps.wordpress.com/category/climate-change/
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In a time of universal deceit, telling the truth is a revolutionary act. - George Orwell

It riles them to believe that you perceive the webs they weave. - Moody Blues

GregWatson · Heavy Crude Joined: Jun 07, 2008 Posts: 132

TheDude

katkinkate

dissident · Heavy Crude Joined: Apr 08, 2006 Posts: 455

Methane is destroyed primarily in the troposphere by reaction with OH and in the upper stratosphere by photolysis. The lifetime of methane in the atmosphere is about 10 years. The reaction of CH4 with O2 is endothermic and the two gases will coexist at normal temperatures. Natural gas explosions require some ignition source.

dissident · Heavy Crude Joined: Apr 08, 2006 Posts: 455

Silly me, it is exothermic. The methane is not going to be released all at once. If we get decades of high levels of outgassing then we will be in a period of CH4 dominated warming since the loss rate is not fast enough.

dohboi · Light Sweet Crude Joined: Dec 05, 2005 Posts: 1441

I'm going to be lazy, too, and take advantage of the obviously considerable expertise available here. I believe I read somewhere that, while methane is usually rated at about 20 times more powerful of a GHG than CO2, that is only because the time scale for the rating is a century. So since most of the methane isn't even around for 90% of that time, it's immediate GH effect--which is well over 100 times more powerful than CO2 over the time scale of a decade--is regularly under stated.

I can't remember the source, though, and my standard references aren't helping me much here. Does anyone else have info on this? Is my mind playing tricks on me?

Cid_Yama

By the time political and economic elites realize the ghastly scope of what's happening, the truly catastrophic changes in our climate and biosphere will probably be unfolding already.

It seems likely that we are staring down the barrel of the full force, worst-case scenarios studied by the IPCC and other research organizations. The future foreseen in those scenarios is hidden amidst a mind numbing tedium of graphs and scientific jargon. The language is bland, almost routine. Implicit in the abstract language, though, are real events and consequences that will devastate the lives of real human beings, on a scale no one has ever seen.

To imagine what it might be like is to invite charges of fear mongering, because it violates the scientific ethos of caution, restraint, and neutrality, the political and cultural norms of can-do optimism. But we've reached the point now where we have to start envisioning what we will face. We have to see the data and projections in human terms. We have to start thinking clearly about what the numbers might mean.

For decades, the right derided environmentalists as doom-sayers. Environmental organizations themselves often hesitated, for fear of losing credibility, to put their case in stark, apocalyptic terms. It may not be politic to say so, but growing evidence suggests that the worst-case forecasts are coming true. The ability of our planet to sustain life is beginning to disintegrate.

The collapse will accelerate and intensify with each passing year. At some point, the cataclysm that ended Earth's Permian era, 251 million years ago, will repeat itself. During the decades or centuries of its recurrence, we will see the end of technological progress, the destruction of our civilization, and quite possibly the extinction of our species.

link
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In a time of universal deceit, telling the truth is a revolutionary act. - George Orwell

It riles them to believe that you perceive the webs they weave. - Moody Blues

jbrovont · Intermediate Crude Joined: Jun 16, 2006 Posts: 701

Great article Cid. Here's another excerpt:

dohboi · Light Sweet Crude Joined: Dec 05, 2005 Posts: 1441

"It seems likely that we are staring down the barrel of the full force, worst-case scenarios studied by the IPCC"

As grim as this sounds, it actually understates the case by quite a bit. The very worst case scenario for total Arctic melt in last spring's IPCC was that it would happen around 2080 or so. This was the very worst case envisioned just a year ago. Reality is proving to be over a half century is ahead of even the very worst case of just last spring.

Right now last years "worst case" looks unbelievably rosy.

Note that the article, excellent though it be, is almost three years old. Much has happened since then to make matters look much worse.