The REAL global warming

Depends on what you mean by a "pollutant". It is a greenhouse gas which causes highly undesirable global temperature change. You can call that a pollutant or not, but that doesn't change the science.

CO2 is most certainly a pollutant when changes in atmospheric concentration of C02 cause change in ocean pH of sufficient magnitude to threaten ocean ecosystems and in particular coral reefs. The evidence on this is already quite clear with Ocean pH having decreased by 0.1 since preindustrial era which much greater changes forecast. The detrimental effects on coral of such changes in pH have been confirmed in laboratory experiment.

You can read more about the evidence for and issues surrounding ocean acidification here:

http://www.tos.org/oceanography/issu...2_caldeira.pdf

But I'm sure that's of no real interest to you as you clearly know everything there is to know about whether CO2 is a pollutant or not. After all there is a clearly a logical progression and no further thought about the matter is required:

CO2 essential part of photosyntheses => under no circumstance can CO2 ever be a pollutant.

There is no logic in that.

Attached. CO2 levels in ocean:

Taking things a little further back, no-one has ever explained to me why we focus so much on CO2. It represents a tiny proportion of the world's atmosphere, whereas water vapour, also a "greenhouse gas", makes up around 95%. I am aware that CO2 is stronger in this respect as it were, but how can CO2 possibly have such a huge effect when it is only 0.038% of the atmosphere?

And exactly how much is generated by humans? And how did coral survive in eras when atmospheric CO2 concentrations were 10 times what they are today? And where did that CO2 come from, assuming T Rex wasn't tooling around in an SUV and leaving the little red light on his telly on?

That's a pretty reasonable question. (But the bit about water vapor being 95% of the atmosphere is quite wrong - the great bulk of the atmosphere is nitrogen).

The attachment shows NASA's assessment of climate forcings for the period 1750 to 2000. "forcings" simply means the degree to which various factors that are known to have changed (known by observation and measurement) have resulted in climate change. CO2 is the most important factor.

Obviously deriving these figures is pretty technical stuff. Reduced to it's simplest expression, one could say that the earth has a heat "budget". The earth receives heat from the sun, some is trapped in the land surface, some in the oceans and some in the atmosphere. What is not trapped is radiated off into space, Atmospheric conditions affect the amount of heat radiated off into space.

There is (or rather has been) a kind of balance here which has kept climate in more or less a stable state over "longish" periods. The question is how much change in atmospheric composition can occur without highly undesirable changes to that balance. That is one of the issues that climate models are intended to improve the understanding of.

Just saying CO2 is only x% of the atmosphere doesn't at all address this question. As a metaphor, one can think about a see-saw on children's playground. If there are equal weights on each end, then it is in a kind of equilibrium. But add some small weight and it tips rapidly. In this case the equilibrium is unstable and the earths heat budget is fortunately not that unstable. How stable it really is the subject of rather extensive research and that is what the determination of climate forcings is all about.

It should be understood that CO2 IS a greenhouse gas. This can be determined from the physics and chemistry. No climate models needed for that. The sixty four dollar question is the magnitude of warming that can be expected due to CO2 in the extraordinarily complex system that is the earths climate. The attached chart shows a piece of NASA's assessment.

One other reason that CO2 is considered so important is that it is expected to increase more rapidly than other greenhouse gases such as methane and CFCs for economic reasons.

And finally CO2 hangs around in the atmosphere for a LONG time until scrubbed by natural processes. Hundreds if not thousands of years. A lot longer than methane. All will not be put right simply by turning off the tap sometime in the future.

Your see-saw explanation shows how finely tuned all this is. It doesn't take too much of anything to disrupt life on this planet. Even a few centimetres rise of the sea level will be disastrous for someone.

Hmm, I'm not sure where I got the 95% figure from. I know that Nitrogen makes up the vast bulk of dry air, but I thought that the atmosphere as a whole was significantly different.

I love the analogy of the see-saw - haven't actually seen that one before. But surely, it is a poor one designed for soundbite purposes. The two must be completely different scenarios.

The other thing I don't understand is the extent of the "panic", given that the relationship between CO2 and temperature is one of diminishing returns - it is not linear.

Partially guilty as charged - it is a bit of a sound bite. But the concept of systems in equilibrium and that equilibrium may be perturbed by what seem to be very small changes to their inputs is very valid. As is the point that you cannot make assumptions along the lines of there is only x% of CO2 in the atmosphere therefore it cannot affect climate. The best evidence available is that it DOES affect climate.

I promise I will look at that more closely when I have a bit more time. Just now I want to reply to a couple of points:

I'd be grateful if you wouldn't put words into my mouth or make judgements about what may or may not be of interest to me. Of course I don't know all about CO2 and whether it's a pollutant or not but I do know that it is literally as natural as breathing. Yes it's true that if we were to breathe in incorrect proportions of nitrogen, oxygen and CO2 it could be dangerous for us, but that happens only in unusual circumstances and it would still be perverse to regard this as pollution. My OED doesn't give a definition for "pollutant", but for "pollute" it gives: 1. contaminate or defile (the environment) 2. make foul or filthy 3. destroy the purity or sanctity of.

"Pollute" is just a highly inappropriate word for CO2, even if it does exactly what the most enthusiastic proponents of man-made-global-warming theory say it does. The greenhouse effect is also perfectly natural; without it we would freeze. The question at issue is whether or not further increases of CO2 will lead to positive feedback in global temperatures leading to a "tipping point".

On CO2 and pH of oceans:

- Is that all oceans? (if it's a global effect then it would have to be).
- How do you know it's the CO2 that is altering the pH?
- those "forecasts" you mention - that'd be with a climate model I suppose. We've seen the quality of the code in some of those models recently used by the UEA CRU. And the model is not the same as the reality.
- laboratory tests are also not the same as in situ.

"highly undesirable global temperature change"

Just for interest, how would you define a "highly desirable global temperature change" then? I mean, let's just imagine you were a real master of the universe (instead of just a trading one), and had your finger on the global thermostat, where now would you be setting it to?

95% & Nitrogen: I don't know if it answers your specific question maiden22, but there is a lot of stuff here: http://www.greenworldtrust.org.uk/Science/Curious.htm

One thing that a lot of people don't seem to realise is that the most significant greenhouse gas is in fact water vapour. I suppose some people might want to call that a pollutant as well.

As for panic. I understand why this is, if the science is exactly what has been claimed: e.g. the existing warming will lead to further release of CO2 from the oceans as they warm up which will (according to the theory) lead to further warming which will lead to further release of CO2 ...etc etc. positive feedback in other words. Yes, it could be catastrophic if it were to happen. The question is: will it? The problem is that this does not take into account so many other variables such as clouds, precipitation, sun-activity....partly because the basic science of how these all fit together still isn't known all that well, apparently.

The models are showing us positive temperature feedback because they have been programmed to do so. I am not saying this has been done for mendacious reasons but because the science is not fully known, so a lot of factors are simply ignored or guessed at.
That's a very crude paraphrasing of a lot of reading; go read yourself, and no, I don't claim to be an expert, I'm just a lay-person with some knowledge of science and the scientific method. Compare dccraig's reference with the one I have given above and see what you make of it all.