[Henry Pool (OP)]

Without Carbon dioxide there wouldn't be any supper on the table. Yet, if we read the papers and magazines it is singled out as the biggest culprit for global warming. The problem is: I have never seen any evidence for this from any real physical tests. Is it really true? If yes,
How much is the influence of varying amounts of CO2 in the atmosphere on global warming? I am particular interested in the range of 0 - 500 ppm . (Current CO2 content in the air is about  375 ppm. It has increased by about 70 ppm's since 1960 and it is apparently increasing by about 2.5 ppm per annum)

 

   

[dentstudent]

Here is a lecture given by Nicholas Stern recently. It is his Blueprint for a Safer Planet and was given at the London School of Economics. It's very interesting...

http://www.guardian.co.uk/science/series/science/podcast.xml

Click on the link, and it's the second podcast down.


IIRC, there is no chance of CO2 levels remaining below 500 ppm. 550 is a minimum, and could very easily go to 750.

[Henry Pool (OP)]

yes, I did listen, and he does exactly the same as what everyone else does in this field, blame carbon emissions and resulting green house gas for global warmimg, without offering any physical evidence or proof.

[dentstudent]

You're welcome.


And in response to your question, noone blames CO2 for ALL the GCC (please stop calling it GW - it isn't). CO2 is PART of it, and is perhaps the most easily addressed. It is well established that CO2 is a GHG, yes? Increased GHGs increases retained energy, yes? CO2 has increased by 25% in the last few decades, yes?

I'm not sure I see what the problem is. Yes, there are other influences on GCC, but (to use that awful phrase) CO2 provides the low-hanging fruit, and it is predicted through extensive modelling, that GCC in response to CO2 increases, is not linear due to feedback processes. By the time that it has reached 750 ppm, there is a roughly 50% likelihood of an increase in temperature of 6 or 7°C, which will have profound effects on the net carbon storage of forests, for example. They will no longer be sinks, but sources due to reductions in photosynthesis, reduced productivity and increased mortality. And if the forests go, not to put too fine a point on it, you're buggered. Completely. Because of CO2.

[Henry Pool (OP)]

SORRY, thanks, for your help!

But I am not there yet! I am trailing years behind. I must first be convinced that CO2 is a green house gas, for which I have not yet seen any physical evidence. My current opinion is that CO2 absorbs in the infra red region, meaning it blocks IR, keeping it out, rather then in. (Similar to ozone blocking UV). So I say that CO2 is not a green house gas. My current theory is that global warming is (mostly) caused by just heat (caused by human activity).   

[dentstudent]

SORRY, thanks, for your help!

Ha! No worries []

Wikipedia is often a reasonable first-stop-shop.

http://en.wikipedia.org/wiki/Greenhouse_gas

I haven't read all of the following, but in any case shows a history of the CO2 GHG case.

http://www.aip.org/history/climate/co2.htm

[Bored chemist]

SORRY, thanks, for your help!

But I am not there yet! I am trailing years behind. I must first be convinced that CO2 is a green house gas, for which I have not yet seen any physical evidence. My current opinion is that CO2 absorbs in the infra red region, meaning it blocks IR, keeping it out, rather then in. (Similar to ozone blocking UV). So I say that CO2 is not a green house gas. My current theory is that global warming is (mostly) caused by just heat (caused by human activity).  

Why have you ignored the evidence put forward in the other thread you started about this?

[Henry Pool (OP)]

sorry, but I have still not yet seen any evidence from anyone that proves to me that carbon dioxide is a green house gas.

[Ophiolite]

sorry, but I have still not yet seen any evidence from anyone that proves to me that carbon dioxide is a green house gas.

Henry, you have provided the evidence yourself. You make this statement. "My current opinion is that CO2 absorbs in the infra red region, meaning it blocks IR, keeping it out, rather then in."

Guess what, you have it half right. The incoming radiation, principally short wave (to which CO2 is transparent)but the outgoing radiation transmitted from the surface in long wave (i.e. infra-red) is absorbed by the CO2.
Let me repeat that, so that you are clear. The incoming radiation that heats the Earth's surface is of a frequency that readily passes through carbon dioxide. The outgoing radiation, of longer wavelength, is trapped by carbon dioxide (and water vapour, and methane) for precisely the reason you have stated.

[Henry Pool (OP)]

This could make some sense to me. But I still want to see the proof. How can you be 100% sure that initially the CO2 does not cause a cooling effect (by keeing some IR out) and then subsequently a warming effect (by keeping some IR in), making the net result more or less zero? I really would like to see the experimental proof of what you say, i.e. proof that CO2 is a greenhouse gas (i.e. warming effect CO2> cooling effect caused by CO2). 

[Ophiolite]

This could make some sense to me. But I still want to see the proof. How can you be 100% sure that initially the CO2 does not cause a cooling effect (by keeing some IR out) and then subsequently a warming effect (by keeping some IR in), making the net result more or less zero? I really would like to see the experimental proof of what you say, i.e. proof that CO2 is a greenhouse gas (i.e. warming effect CO2> cooling effect caused by CO2). 

This could make some sense to me. But I still want to see the proof. How can you be 100% sure that initially the CO2 does not cause a cooling effect (by keeing some IR out) and then subsequently a warming effect (by keeping some IR in), making the net result more or less zero? I really would like to see the experimental proof of what you say, i.e. proof that CO2 is a greenhouse gas (i.e. warming effect CO2> cooling effect caused by CO2). 

There are a wealth of experimental data demonstrating the absorption of infrared radiation by CO2. You appear to have accepted these data. That is only one half of what makes it a greenhouse gas. The other half is the fact incoming solar radiation from the sun is dominated by short wave radiation - and CO2 is transparent to this - while outgoing radiation is long wave, which is absorbed by CO2. It is the difference in inocming and outgoing wavelentghts that allows the CO2 to act as a greenhouse gas.

Here is an interesting historical link on the topic.
http://www.aip.org/history/climate/co2.htm

[Bored chemist]

"How can you be 100% sure that initially the CO2 does not cause a cooling effect (by keeing some IR out)"
"out " of what? The atmosphere is part of the earth.

[Henry Pool (OP)]

when I was last at school I learned that the sun emits the whole spectrum of radiation, from the invisble UV right through all colours of the rainbow to the invisible on the other side. That includes the radiation that C-O. Has something changed in the 40 years that I was not at college? So my theory is still that the C-O blocks as much radiation coming in as what it holds by preventing it going out. (similar to ozone blocking UV). But tell me that have some experimental proof for the statement that you are making.

[Henry Pool (OP)]

You see what the problem is? Whenever you ask for experimental proof it is simply not there. I still have not seen any physical proof or evidence from any tests that carbon dioxide is to blame for global warming. Everyone thought that someone would do it, in the end no one did it. Surely, you can only believe in what you can verify?

The scientists who predict climate warming just study the increase in temperature of the oceans, and then they can quite accurately predict what the increase in energy per square area will be for the next couple of years or decades. Then they blame green house gasses. What else must they do? It has become a belief. That must be it. wow, sorry that I am not one of the faithful to this belief. My current theory, based on the proposed mechanisms, is that the so-called green house gasses may prevent as much heat from coming in as the heat that they trap. 

Where does that leave us? well I still have my own theory which no one can proof wrong. I say; the reason why the temperature in the oceans are rising is very simple. It is the same reason as what you note what happens when you put the kettle on. It is the energy that you put in that makes the water in the kettle warm. I think all 6.7 million of us just do not realize how much energy we are putting in the kettle called earth.
     

[Henry Pool (OP)]

I'm so sorry. Are we 6.7 billion now living on earth?

[Karsten]

This could make some sense to me. But I still want to see the proof. How can you be 100% sure that initially the CO2 does not cause a cooling effect (by keeing some IR out) and then subsequently a warming effect (by keeping some IR in), making the net result more or less zero? I really would like to see the experimental proof of what you say, i.e. proof that CO2 is a greenhouse gas (i.e. warming effect CO2> cooling effect caused by CO2). 

This is the way I understand it:

Sunlight (UV, visible, and infrared) arrives from the sun at our planet. When it strikes the atmosphere, some gets reflected, some gets absorbed, some goes right through and reaches the ground. When visible light strikes the ground, especially dark surfaces, it gets transformed into infrared. Anything in our atmosphere that has the ability to absorb infrared and allow our atmosphere to get warmer seems to be a problem. Higher CO2 in our atmosphere is not blocking infrared out, it is collecting it better than an atmosphere with less CO2. Both ways. Incoming and leaving. Who says that CO2 has ANY cooling effect?

[Henry Pool (OP)]

"seems" is the word I caught. Show me the proof and I am your buddy!
It is I who said that CO2 causes some cooling. Because it absorbs IR in the IR region. Meaning it (also) blocks IR. And of course it traps it when it tries to return to space. So, the net effect is zero?

[BenV]

It is I who said that CO2 causes some cooling. Because it absorbs IR in the IR region. Meaning it (also) blocks IR. And of course it traps it when it tries to return to space. So, the net effect is zero?

So it absorbs it on the way in, heating the atmosphere, and then it absorbs it on the way out, heating the atmosphere...

Don't forget that there is IR created on the ground too - it's not that the only IR around comes from the sun.
 
Net effect is clearly far from zero...

[Henry Pool (OP)]

Wake up man! If CO2 blocks IR radiation coming in, it means that it cools down (for us).Then it also traps it when it tries to leave. So it warms up. So, I say, the net effect is zero? Nobody knows. Did someone test it?   It seems not/ I have not seen any data related to an actual verifyable experiment!

[Bored chemist]

The CO2 in the air absorbs IR directly from the sun; this warms the atmosphere and some of that heat is transfered to the groud, partly by reradiation, partly by convection. Also visible light shines through the CO2 and warms the surface of the earth.
Both these effects warm the planet.
As the planet gets warmer it emits more radiation but, because it is a lot colder than the sun it doesn't emit any visible light - just IR.
Some of that IR is absorbed by the atmosphere's CO2 and is carried by the winds back to the surface.
In order to reach thermal equlibrium where the heat absorbed from the sun is the same as that radiated the world has to be slightly warmer than it would be without the CO2 getting in the way of some of the outgoing IR.

Also, you keep asking for proof. Did you watch the youtube video?
It's not great proof, but it's a lot better than any evidence you have put forward.

I take it you didn't understand my earlier post
""How can you be 100% sure that initially the CO2 does not cause a cooling effect (by keeing some IR out)"
"out " of what? The atmosphere is part of the earth."
If it's a sunny day and I put my hand up to keep the sun off my face, it doesn't help keep me cool, because my hand is still getting warm, and it's part of me.