Understanding the Greenhouse (Gas) Effect

[arkie87]

No, global warming won't turn the earth into some venusian hellhole. But comparing the current increase in the greenhouse effect with the one during the paleocene is disingenuous. The current increase is way faster than any natural effect and thus the biospheres of the earth don't have time to respond. If you wait a couple of millenia the planet would be a lush haven. But on the short term (short term being 50-100 years) it means desertification, flooding, more extreme weather, a minor mass extinction and all around bad stuff.

Are we sure the current rate of warming is unprecedented? The climate trends for the past 400,000 years (from ice core data) do not appear smooth. If you zoom in, you might find short periods of time (and by short, i mean thousands of years), where climate was warming (and cooling) as rapidly as now, even though the longer term trend was much smoother/less steep.

[KerikBalm]

CO2 is approximately double what it has been historically through these "recent" (geologic scale, 100,000's of years scale) cycles.

And that ~100% excess happened in the span of about a century.

Yes... it is much faster, and going much higher.

Earth will eventually become a venusian hellhole anyway...but we aren't helping delay that...

[arkie87]

CO2 is approximately double what it has been historically through these "recent" (geologic scale, 100,000's of years scale) cycles.

And that ~100% excess happened in the span of about a century.

Yes... it is much faster, and going much higher.

Earth will eventually become a venusian hellhole anyway...but we aren't helping delay that...

I was referring to temperature, not CO2; hence "warming"

[peadar1987]

That's all for now. For the time being, I'm going to skip replying to everybody else's posts--which is a good thing, because among other issues, I really need to give one person in here (no, Arkie--not you) a stern talking-to for committing a pretty hideous debate foul.

Moi?!

[arkie87]

Moi?!

I guess you will find out? Has he PM'ed you?

[GeneralVeers]

I guess you will find out? Has he PM'ed you?

Uhhhhh.....no. I didn't PM him about it. Personally, I feel that woulda been kinda creepy if I had. (cyber stalking!) Anyway:

Moi?!

Vous.

Remember this little snippet from a few days ago?

Contrary to what you have said, water vapour does not strongly absorb visible light from the sun.

I never said water vapor absorbs strongly in visible light. Disagree? QUOTE ME.

I said water vapor absorbs strongly in infrared.

Debate foul. You claimed I said something that I very definitely DID NOT SAY. Don't ever do that. Not to me or anybody else. Just not ever.

[peadar1987]

You said that water vapour (and other greenhouse gases) absorbed incoming solar radiation to an equal or greater degree than they absorbed outgoing thermal radiation from earth. It has been repeatedly stated (on at least 3 separate occasions in this thread) that the sun's emission spectrum is overwhelmingly in the visible range, whereas the earth's emission spectrum is in the infra-red.

So my apologies, you were incorrect in a slightly different, but functionally almost identical way than I made out in my post.

Edited August 19, 2015 by peadar1987

[arkie87]

Wow, that's a little bit of an over-the-top reaction.

You said that water vapour (and other greenhouse gases) absorbed incoming solar radiation to an equal or greater degree than they absorbed outgoing thermal radiation from earth. It has been repeatedly stated (on at least 3 separate occasions in this thread) that the sun's emission spectrum is overwhelmingly in the visible range, whereas the earth's emission spectrum is in the infra-red.

So my apologies, you were incorrect in a slightly different, but functionally almost identical way than I made out in my post.

You should quote him exactly. I think, when i read what he wrote, it seemed he was implying that water absorbs solar radiation as well as infrared, but actually (after i re-read what he wrote a few times), it appears he was actually implying that the sun emits a significant portion in IR spectrum (and he provided a reference), which is contrary to the source i supplied.

Here is the passage im talking about:

If by water vapor, you meant cloud coverage [...]

I didn't. I meant water vapor below cloud level, in its transparent (and invisible) form. Non-cloud water vapor absorbs strongly in the infrared range

This might imply that Wedge thinks non-cloud water vapor can absorb visible light; however, it appears he doesnt think that, but rather, that 50% of the solar flux is in the IR spectrum (which water vapor obviously absorbs). I'm not sure how this is possible (unless our two definitions of IR spectrum are different i.e. 10um vs 1 um)

See his response:

Wikipedia https://en.wikipedia.org/wiki/Sun says the following:

Note that the above is sunlight before it enters the Earth's atmosphere. Infrared is the number one component. Any greenhouse gas that absorbs infrared will absorb some of that before it hits the ground.

Edited August 19, 2015 by arkie87

[GeneralVeers]

Wow, that's a little bit of an over-the-top reaction.

Squeaky wheel gets the grease. Yes, I'm touchy about this particular debate foul. I've been in a lot of arguments in a lot of debate forums, and far too many times, I have had people use that tactic against me (or against each other!) deliberately. Pretty please with sugar, avoid it whenever you can--and, by all means, keep a close eye out for other people using that trick on you. This chat forum is nicer than most; elsewhere on the web, people can get really nasty.

Alrightey, back to the Quote Wars.

You said that water vapour (and other greenhouse gases) absorbed incoming solar radiation to an equal or greater degree than they absorbed outgoing thermal radiation from earth. It has been repeatedly stated (on at least 3 separate occasions in this thread) that the sun's emission spectrum is overwhelmingly in the visible range

And I posted a source (exactly once) proving the opposite. With bland, boring, easily-readable numbers instead of a fancy graph.

It's not readily apparent from the graph you posted, but if you were to sum up the area under the curve (which requires integrals, and I was never a big fan of calculus) you'd find the infrared emissions are the largest source of energy. It simply doesn't look like that on the chart because the peak is in the visible range.

No, global warming won't turn the earth into some venusian hellhole. But comparing the current increase in the greenhouse effect with the one during the paleocene is disingenuous.

Lemme tell you what's disingenuous: claiming that I'm disingenuous? That's disingenuous.

I never said I was comparing the greenhouse effect today versus the Paleocene. I was comparing the temperature. The Paleocene epoch was significantly warmer than today; that is scientifically verified fact. Let me point out specifically that I have no idea why the Paleocene was as warm as it was; could be greenhouse effects, could be something else entirely. I have no idea why the Earth was so warm back then, and it doesn't matter. The Earth was much warmer than today--yet the Global Warming Doomsday did not happen.

Keep this in mind: in order to prove a scientific theory--in order to make the conceptual leap from "theory" to "fact"--you must perform a test. Not very easy to do with Earth, because we've only got the one planet. But we can observe what has happened in Earth's past. And that's what the Paleocene is: a test of global warming theory.

Theory debunked.

What altitude are you at? If you're higher up, air temperatures are going to be cooler, which keeps the ground cooler.

I'm around a mile up. And the answer is no: the air around here is not cooler. For the last couple of weeks it's been pretty warm out. In the shade.

Why is Kilimanjaro cold? Because it has a high albedo.

True.

Why does it have a high albedo? Because it is covered in snow.

Also true.

Why is it covered in snow? Because it is cold.

Also also true. All three of these things are scientific fact.

But then you get a chicken and egg situation.

So what? Why should that be a problem? Just because we can't answer "which came first, the chicken or the egg" doesn't disprove the existence of chickens or eggs. All three of the above are happening on top of Kilimanjaro, and not knowing which one happened first doesn't change the fact that all three are happening.

None, unfortunately, but because the air temperature is consistently below zero, it's going to keep the surface temperature down as well, by shifting the equilibrium between convection and radiation.

Not true. At high altitude, the air is (generally) colder. But it's also thinner. Colder air does increase the rate of cooling, but thinner air decreases the rate of cooling because there are fewer molecules to perform convection. Remember, I pointed out earlier on that I've been there. You're only cold on the side facing away from the Sun. At high altitude, radiation becomes the primary factor. As you go higher, you more closely approach conditions on the Moon--which is literally boiling hot on the day side.

I picked based on humidity. I could easily have compared Delhi and Mumbai as well. And I'll throw in Bikaner in the Thar desert as well.

Delhi: http://en.tutiempo.net/climate/2014/ws-421820.html

Mumbai: http://en.tutiempo.net/climate/2014/ws-430030.html

Bikaner: http://en.tutiempo.net/climate/2014/ws-421650.html

Average temperatures in Mumbai are actually warmer than in Bikaner. Both Bikaner and New Delhi have comparable average temperatures in spite of Bikaner being dry, and New Delhi being extremely humid.

I already said you shouldn't compare cities to each other. Things as simple as different construction methods can produce cities with widely varying albedos. Compare cities to deserts. I checked Bikaner and Mumbai for climate numbers; both cities are cooler than the local deserts--and more humid than the local deserts.

Your examples don't disprove my theory. They confirm it.

The point I was trying to make was that this isn't how deniers usually talk about the effect of water vapour. What we should be saying is:

"CO2 warming on its own could cause problems, but this warming will cause more greenhouse gases such as water vapour to be carried in the atmosphere, increasing the effect by a factor of two or three."

Then why don't we see that in humid areas? Once again: theory debunked simply by looking out at the world around us. The sum total effect of water vapor is to cool hot environments and warm cool ones. The presence of water vapor in any given area of the Earth does not increase the average or mean temperature by any measurable amount. From all available observations: water vapor acts as a buffer and a moderator, not as a space heater.

This might imply that Wedge thinks non-cloud water vapor can absorb visible light; however, it appears he doesnt think that, but rather, that 50% of the solar flux is in the IR spectrum (which water vapor obviously absorbs). I'm not sure how this is possible (unless our two definitions of IR spectrum are different i.e. 10um vs 1 um)

All stars, even the "colored" ones, emit energy in a very broad range of frequencies, all the way from infrared through visible, into the ultraviolet, X-rays, and gamma radiation. The only notable exceptions are spectral absorption lines due to specific elements in the star. A lot of stars do in fact shine most brightly somewhere in the visible spectrum, but the visible spectrum is a very narrow band of frequencies compared to the infrared range. Sum up the total energy emitted across the entire infrared frequency range, and you've got quite a lot of energy.

[peadar1987]

Squeaky wheel gets the grease. Yes, I'm touchy about this particular debate foul. I've been in a lot of arguments in a lot of debate forums, and far too many times, I have had people use that tactic against me (or against each other!) deliberately. Pretty please with sugar, avoid it whenever you can--and, by all means, keep a close eye out for other people using that trick on you. This chat forum is nicer than most; elsewhere on the web, people can get really nasty.

Grand so, this debate has been pretty good-natured so far, I don't want to be the one to ruin that.

Alrightey, back to the Quote Wars.

And I posted a source (exactly once) proving the opposite. With bland, boring, easily-readable numbers instead of a fancy graph.

It's not readily apparent from the graph you posted, but if you were to sum up the area under the curve (which requires integrals, and I was never a big fan of calculus) you'd find the infrared emissions are the largest source of energy. It simply doesn't look like that on the chart because the peak is in the visible range.

[KerikBalm]

Debate foul. You claimed I said something that I very definitely DID NOT SAY. Don't ever do that. Not to me or anybody else. Just not ever.

Says the guy who did the same thing to me, but to a much greater degree.

Its ok when you do it, but not when its done to you?

I'm still waiting for my apology.

[Bill Phil]

Everybody chill out, please!

[Vanamonde]

Everybody chill out, please!

The moderation team seconds this request.

[PakledHostage]

Keep this in mind: in order to prove a scientific theory--in order to make the conceptual leap from "theory" to "fact"--you must perform a test.

...

Theory debunked.

You keep using that word, I do not think it means what you think it means...