Global Warming: Proposed Cooling Mechanism?

Factual Questions
1

Hey folks, I’ve chanced upon this here fine site a couple of times ago, and have now decided to jump right into the fray in light of the current ‘heating up’ of global warming debate with a little question of my own… Is there some ‘introduce yourself’-thread, by the way?

I’m not sure if I’m posting in the right forum, since it is a question I’m going to ask, but I’m not entirely sure if it has a factual answer, so if the mods feel the thread would be more appropriate in the Great Debates section or somesuch, I’d appreciate the move…

Well now, here goes:
My own understanding of global warming is, I must confess, rather far from complete; basically, my naive view is:
[ul]
[li]CO2 is a greenhouse gas, i.e. a gas that has the property of trapping energy in the form of infra-red radiation[/li][li]we’ve heightened the concentration of CO2 in the atmosphere by a considerable amount - I’ve read 35%, but that’s speaking purely from memory[/li][li]this means that the earth is now storing more energy than it was before[/li][li]this means it’s getting warmer.[/li][/ul]
(First of all, is this correct, and if not, where are my major misconceptions?)
Now, without delving to deep into the arguments, counter arguments, counter-counter arguments etc., is there a proposed mechanism that leads to the earth cooling off again, i.e. (I suppose) the radiating of excess energy into space/transformation of heat energy into some other form?
I mean, I’d think this would be a primary basis for attacking the claim that the earth is warming and that we’re at least partly to blame, but I can’t recall ever reading 'bout one; and furthermore, it seems to me that in lieu of such a mechanism any refutation of global warming claims lacks in basis (as in pointing out perceived flaws of the theory without proposing a viable alternative).

So, uh, that got a bit more longwinded than I’d anticipated, so to be a little more concise with my question: is there any (theoretical, real, proposed, supposed, what have you) mechanism that counteracts CO2’s greenhouse effect? (And if not, is there any basis for attacking global warming?)

Of course, if that’s already been covered, I’d be thankful for a link…

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Whoops, sorry, that oversized bit was meant to be small, originally…

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The biggest problem with any of these schemes is that the heat you’re trying to dump is at a fairly high level of entropy - it’s spread out in the environment. Concentrating it back together in order to throw it away would require the expenditure of more energy than you’d be gathering up, so it would just make things worse.

Passive solutions such as creating large reflectors etc wouldn’t suffer this problem.

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That’s pretty much what I was thinking. I’m just puzzled by the argumentation against global warming - how’s the earth supposed to retain a stable temperature if it’s gathering energy? It’s just that (to my best recollection) I’ve never seen any counter argument to the rather simple reasoning that I’ve listed above, while I would expect it to be at the very core of any refutation of global warming…

Yes, though I’m myself in favour of dropping a lot of small particles of some form of metallic foil in low earth orbit, who knows, maybe things could be arranged so we’d get a nice sparkly sky instead of the old lame blue, or maybe even some rainbow colours… I mean, besides reflecting a bit of the sunlight, just think about the wonders it’d do for world morale if the sky was one big rainbow!

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‘we’ve heightened the concentration of CO2 in the atmosphere by a considerable amount - I’ve read 35%, but that’s speaking purely from memory’

Are you saying that you’ve read that 35% of the ‘gas’ in greenhouse gas is CO2?

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:confused:
I’m not sure if I understand the question (maybe I misused ‘heightened’, my English’s sometimes a bit clumsy), but what I’m saying is that the concentration of CO2 in the atmosphere appears to have gone up by 35% since we started burning fossil fuel about 150 years ago (yes, there’s probably some debate in those figures, so let’s look at this as a rather rough estimate - what’s important is that it has gone up).
This chart seems to back me up on that…

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I think he’s saying we’ve increased the amount by 35% of what it was previously. That doesn’t mean it ends up constituting 35% of the whole mix

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The Earth is always shedding energy, by radiating it into space as infrared. The rate at which this occurs depends on several factors, including the amount of CO[sub]2[/sub] in the atmosphere and the temperature of the Earth. The higher the temperature, the faster the heat is radiated away, while the more CO[sub]2[/sub] and other greenhouse gasses, the slower it’s radiated away. If the Earth is in equibrium, or close to it (as is typcially the case), the rate at which energy is radiated away is equal to the rate at which the Sun is adding energy to the planet, so the planet holds onto a constant amount of energy, and thus stays at a constant temperature.

However, if you take a planet at equilibrium, and add more greenhouse gasses, the rate at which energy is lost is decreased, but the rate at which it’s added stays the same, so energy accumulates, and the temperature increases. As the temperature increases, the rate of energy loss also increases, and you eventually get to a new equilibrium, where the temperature again stays constant (but larger than it was at the old equilibrium).

If you now take a planet at this new, hotter equilibrium, and decrease the greenhouse gasses, then the planet sheds heat more efficiently, and so (for a while) it’s losing energy faster than it’s gaining it, and cools down. As it cools down, the rate at which it’s losing energy decreases, until eventually it gets back to the old equilibrium, and stays there (back at the lower temperature).

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Here is a great page detailing 5 ways to engineer a cooler planet:

http://www.msnbc.msn.com/id/17632436

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Standard procedure lately has been for new folks to introduce themselves by starting a global warming thread of somesort :slight_smile:

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Couldn’t we just plant more trees?

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Or 911 conspiracy, but the global warming ones are marginally more respectable.

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Hey, but this one doesn’t come across as a troll or a moron, and this thread is evoking positive, constructive response. No complaints here.
Back on topic, one thing I’ve heard proposed is seeding the oceans with iron, the theory being that this would promote microbial growth which pumps down CO2. I feel like I’ve also seen this debunked, though I can’t remember where or by what mechanism.

There’s a few problems for this mechanism. First, anything in low Earth orbit tend to deorbit eventually; tiny imperfections in the orbit, collisions, drag from the extremely thin atmosphere up there, and even solar wind will eventually push anything in that orbit back into the atmosphere. Your pieces of foil probably wouldn’t pose any danger to anything on the ground, as they’d probably burn up quickly, but it’d be expensive to have to keep putting the stuff back up there.

There’s also the problem of dealing with the foil pieces while they’re up there- one of the biggest hazards to space travel right now is that we’ve littered the space around Earth with thousands of pieces of debris; everything from wrenches dropped on spacewalks, loose bolts, satellites that have outlived their usefulness, even the splintered target of that Chinese satellite-killer missile a few months back. If any of these things hits a spacecraft, it’s likely to be moving thousands of miles per hour, and even a little nick on a spacecraft’s thermal shielding can be fatal, as Columbia proved. Your foil cloud would make it nigh on impossible to launch anything into space.

Finally, I don’t think it would make any kind of rainbow in the sky- the point of this foil is to reflect light away from the Earth. If it was working, it would simply make the sky and the sun appear dimmer.

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Or dump a big block of ice in the ocean “every now and then”?

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Thanks for your answer; however, this wasn’t quite what I was trying to get at. I roughly understand the way things work when left to their own devices, that is during natural circles of temperature variance, but my question is: now that we’ve tipped the earth out of it’s near-equilibrium, is there any proposed mechanism by those that oppose global warming that counteracts the greenhouse effect of CO2?
What you just said seems to make it necessary that the temperature is going to rise if you raise the CO2 concentration in the atmosphere. Yet there’s still a lot of loudly mouthed dissent, and I want to understand where that’s coming from, if it has any theoretical basis at all. See, if the causation ‘more CO2 -> warmer earth’ is indeed solid, all further debate seems kinda pointless to me, and I’d think for any attack on global warming you’d first need to come up with a valid reason how it could be possible to raise atmospheric CO2 levels without the earth warming up.
I just want to know if anybody trying to ‘disprove’ global warming ever came up with such a reason, and if so, what that reason is.

Filmsg, thanks for that link, those are interesting ideas (although most seem a little impractical), but also not quite what I was looking for…

I hope I didn’t strike any wrong chord with my question, sorry if I did.

appleciders, I wasn’t totally serious with my proposal (but now that you mention the orbital decay, possibly another positive aspect would be a lot more shooting stars at night, and we could all use a wish or three)… As for the rainbow sky, well, if the orientation of those tiny little foil pieces is purely statistical, there’d always be a significant number reflecting the sunlight in the right angle that if you’d coat them with a dispersive layer you’d get nice coloured rings around the sun, while still considerably more of them would deflect light away from earth (well, maybe)… hey, if we’re gonna spend a couple of trillion bucks on that and considerably hamper space travel, we could at least make it look pretty. :wink:

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Scratch that last speculation about the rainbow sky, now that I think about it there’d of course also be every other orientation present at every angle, so that all the reflected colours would add to white light again. And I’d imagined it looking so nice… little glass balls might work, but they wouldn’t reflect anything away, or would they? Maybe from a certain angle on?
Well, the effect would probably be lost in the atmosphere, anyway…

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Don’t worry about it - you’re doing fine.

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Nope, just making a joke about how many new people seem to be starting off with GW posts.

Nothing wrong with that though, and the resulting threads are usually interesting.

Most semi-serious dissenters awknowlege that the Earth is warming, they just deny that its (primarily) due to human activity. So for most of them, it isn’t necessary to create a different way for the Earth to dispose of extra heat, they just need an alternative explanation for the reason its getting hotter.

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We could. But we need to plant a whole lot more of them. Plus, to be really effective we need to do this in tropical areas - in colder climate trees aren’t that good at sequestering CO2.

Now, if You have way to convince Brazilians not only to stop cutting Amazonian rainforests, but replant them everywhere in their country, then maybe we have problem half-solved. Well, quarter-solved.

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Gee, this place moves fast… spend a weekend in a drunken stupor (in the interest of scientific research: countering a hangover by continuing to drink does not work, at least not for me), and you have to retrieve your thread from page 3…

But wouldn’t such a line of reasoning still need an argument as to why the increase in CO2 doesn’t contribute to the warming, or alternatively why the CO2-increase isn’t man-made?
Or is the acknowledgement that the earth is warming in part due to greenhouse effects, but that the dominant cause is something else (presumably of natural origin)? Wouldn’t that just add the convenience of not being the ones to blame to the issue, since we’d still have to try and come up with solutions for the same problem (or a way to live with its effects), because the contribution by the greenhouse effect would be the only thing we could at least hope to affect, if the underlying cause is natural?