Global warming

[rpg.314]

double post, sorry.

 

[rpg.314]

The real smoking gun isn't the rise in temperature of the surface, but rather the decrease in temperature of the stratosphere, as this is the fingerprint of greenhouse gas-induced warming.

And why should it be so?

 

[KimB]

And why should it be so?

I'm not sure what you're asking. Could you clarify, please?

 

[rpg.314]

I'm not sure what you're asking. Could you clarify, please?

Why (and how) is cooling of stratosphere a signature of CO2 induced warming?

 

[Gubbi]

Why (and how) is cooling of stratosphere a signature of CO2 induced warming?

The stratosphere is cooling for two reasons:
1. Less ozone means less UV absorption and thus a smaller energy input [to the stratosphere].
2. Green house gases retard IR radiation, trapping energy in the troposphere, heating it, the ground and seas. Again the stratosphere receives a smaller energy input [to the stratosphere].

If the stratosphere was heating up, more energy would be radiated to space, and the earth would be cooling

Cheers

 

[KimB]

Why (and how) is cooling of stratosphere a signature of CO2 induced warming?

Well, Gubbi already answered, but I'll add a little bit more.

In most wavelengths the Earth emits, the stratosphere is the part of the Earth that is visible from space. So if the stratosphere cools down, the Earth, as seen from space, is cooler. A cooler stratosphere, then, means less radiation is emitted into space, which causes the Earth to warm up (because the same amount of radiation comes in).

 

[FUDie]

Well, Gubbi already answered, but I'll add a little bit more.

In most wavelengths the Earth emits, the stratosphere is the part of the Earth that is visible from space. So if the stratosphere cools down, the Earth, as seen from space, is cooler. A cooler stratosphere, then, means less radiation is emitted into space, which causes the Earth to warm up (because the same amount of radiation comes in).

Something doesn't compute. You're saying that as the Earth warms up, it appears cooler from space? Doesn't that violate the whole principle of black body radiation?

-FUDie

 

[Sxotty]

Why would that violate the black body principle?

If you have the same amount of energy being input to a system, but the system is putting out less energy then it is gaining energy. That seems to makes sense to me.

 

[arjan de lumens]

Something doesn't compute. You're saying that as the Earth warms up, it appears cooler from space? Doesn't that violate the whole principle of black body radiation?

-FUDie

The principle of blackbody radiation applies to the radiation that is emitted from the Earth's surface - which is NOT the same as the radiation that escapes into space; the whole point of greenhouse gases is that they reflect some of the radiation from the Earth's surface back to the surface.

 

[KimB]

The principle of blackbody radiation applies to the radiation that is emitted from the Earth's surface - which is NOT the same as the radiation that escapes into space; the whole point of greenhouse gases is that they reflect some of the radiation from the Earth's surface back to the surface.

I think a more accurate way of stating it is that more GHG's mean that more radiation is not emitted from the surface, but instead from the (much colder) atmosphere, because the atmosphere blocks certain wavelengths. And when you cool the upper atmosphere, you reduce the amount of energy that leaves the Earth, causing the Earth to heat up.

 

[WhiningKhan]

Arjan was quite accurate enough, you are just creating more confusion by mixing causality here:

And when you cool the upper atmosphere, you reduce the amount of energy that leaves the Earth, causing the Earth to heat up.

Reformulation for clarity: You limit the heat transfer of the atmosphere, which causes the Earth to heat up and the upper atmosphere to cool down.

 

[gamervivek]

"A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range."

reflect is a bad word to use.

"I think a more accurate way of stating it is that more GHG's mean that more radiation is not emitted from the surface, "

wut?

edit:

nvm

 

[Squilliam]

Any real good news from Cancun or was it a lot of hot air? I can't find any really summary as to what actually happened there.

 

[KimB]

Any real good news from Cancun or was it a lot of hot air? I can't find any really summary as to what actually happened there.

I found this:
http://www.telegraph.co.uk/earth/en...meeting-reaches-climate-change-agreement.html

Not sure what it'll mean, though.

 

[Squilliam]

Thanks.

 

[gamervivek]

 

[Squilliam]

Lake temperatures are up right? So soon as a positive consequence of warming we may be able to swim in some of them.

 

[Squilliam]

...we should refrain from asserting that the planet has warmed (or cooled) in any given period without IMMEDIATELY pointing out that such theories are based upon data that critics have called into question. It is not our place as journalists to assert such notions as facts, especially as this debate intensifies.

According to an internal fox memo.

 

[Grall]

It's not a "theory" that the planet has warmed if we have hard data showing that it has in fact warmed.

Fox living up to its self-professed "balanced" ideal as usual, I see.

 

[Squilliam]

It's not a "theory" that the planet has warmed if we have hard data showing that it has in fact warmed.

Fox living up to its self-professed "balanced" ideal as usual, I see.

Im sure they don't do the same when some economist goes on their station and portrays his economic theory, or when some guy talks about the reason why terrorists exist or when discussing religion!