Anthopogenic Global Warming Myth or Real ?

[a_unique_person]

DogB




BANG….

So nicely put.

Not being contrary.. being sensible.. almost EXACTLY how I read the situation.

The only real scientific consensus seems to be.. we cannot find natural reasons for global warming.. man is increasing CO2.. man is the reason…

All other CO2 science seems to point on so LITTLE effect on GW !

Its so “unscientific” !

No, read the IPCC report.

 

[Spud1k]

Logical but this still begs the question - why assume a significant role for CO2 at all?

It's not assumed, it's been known for a long time and it comes down to some very basic physics. The sun emits most of its energy in the visible and UV while the earth emits in the IR due to their respective temperatures and resulting blackbody functions. Carbon dioxide is a strong absorber in the IR and a weak one in the visible and UV, so makes a very good greenhouse gas. Quantifying how much upwelling heat energy CO2 traps in the atmosphere (preventing it being lost to space) is a fairly straightforward calculation. If there was no carbon dioxide in the atmosphere, the world would be a significantly colder place and conversely, if we continue to get more, it'll get warmer.

Upshot is that you can predict a big chunk of long-term warming from increases in CO2 alone; according to the best calculations, there is no bigger contribution to the current warming. The temperature increase lags behind the concentration increases because of the earth system's heat capacity (mainly in the water in it). There's also some variation due to ocean currents, but the overall trend remains.

 

[Spud1k]

In the past the CO2 levels have tended to follow temperature changes, now they're driving it. If we accept this we must accept that paleo-climatic behaviour is only of limited predictive use.

Paleo-climatic behaviour on its own is of highly limited predictive use, given that there were no people back then. It's very disingenuous to claim the whole interglacial CO2 and temperature plot proves CO2 causing climate change. That's not to say the trend isn't significant; it points to a potentially very serious feedback mechanism. But the two should never be confused and there are people on both sides who are guilty of that.

 

[Spud1k]

All other CO2 science seems to point on so LITTLE effect on GW !

Really? Like what?

 

[Spud1k]

But unlike Evolutionary theory (example) which keeps hitting with its predictions.. AGW theory keeps missing.. I am sure that it’s a matter of time .. scientists will have it all nailed down some time.. for now though its seems far to much is being based on far to little !

Climate science represents a massive global community of scientists, each of whom has their own predictions and they can't all be right on the specifics. Given that the earth is a chaotic system and there are so many unknowns in the future, no-one will ever be able to forecast the earth's temperature with absolute certainty. However, since at least the seventies, the general prediction has been one of global warming (the global cooling prediction was always from a minority). If you follow the long-term trend since then, global warming has indeed happened. Could you explain to me how that constitutes a 'miss'?

 

[TrueSceptic]

I appreciate the support but unfortunately I have to disagree with you two also.

The problem is that I am an amateur. There’s thousands of scientists working in the field that back the CO2 mediated warming idea whole heartedly.

It’s ludicrous to assume they’re all either wrong, misguided or just riding the bandwagon.

The hugely more logical premise is that I am simply ill educated in this matter.

Yours is a sensible viewpoint and somewhat at odds with that of most amateur "sceptics", who are quite happy to believe that mainstream science has got it all wrong. To make this possible they then have to believe in some vast conspiracy. Factor in the far-right politics of most "sceptics" and it becomes impossible to believe that their claims are much to do with science or to take them seriously.

I’m working on becoming more educated which will, hopefully, ease my disquiet with this aspect of the hypothesis. It hasn't yet however.

Have you read The Discovery of Global Warming?

 

[TrueSceptic]

It seems we're very much on the same page. It’s comforting to know I’m not the only one.

I greatly dislike the 'you're either for us or against us' type of attitude this debate often engenders and I dislike the terms 'warmer' and ‘denier’ equally.

"Denier" and "Denialist" are appropriate descriptions for people who continually lie, misrepresent the work of others, and endlessly recycle arguments refuted long ago. Many of them do this from an anti-regulation far-right viewpoint and used the same tactics in the debate about tobacco and health.

I'd like to think it's possible to logically question some aspects of the theory without causing too much angst. After all, if the hypothesis is valid and robust it should be able to easily withstand my critical musings.

Of course. The information is out there. You just need to know which sources to trust.

 

[Spud1k]

"Denier" and "Denialist" are appropriate descriptions for people who continually lie, misrepresent the work of others, and endlessly recycle arguments refuted long ago. Many of them do this from an anti-regulation far-right viewpoint and used the same tactics in the debate about tobacco and health.

My use of the term 'denier' is slightly different, but amounts to the same thing more or less. A denialist argument for me when the basis of the argument isn't what's important, just that it somehow undermines the conclusion. This is evidenced by the round robin of counterarguments we've been seeing here. Most of the noise against AGW stems from people not liking what they're hearing when it comes the conclusions, which I can understand to an extent; just because climate change is helping to pay my mortgage, doesn't mean I'm looking forward to it. However, doesn't change the fact that the more scientific approach is to focus on specific issues, establish the facts and then make conclusions accordingly.

 

[TrueSceptic]

My use of the term 'denier' is slightly different, but amounts to the same thing more or less. A denialist argument for me when the basis of the argument isn't what's important, just that it somehow undermines the conclusion. This is evidenced by the round robin of counterarguments we've been seeing here. Most of the noise against AGW stems from people not liking what they're hearing when it comes the conclusions, which I can understand to an extent; just because climate change is helping to pay my mortgage, doesn't mean I'm looking forward to it. However, doesn't change the fact that the more scientific approach is to focus on specific issues, establish the facts and then make conclusions accordingly.

My definition wasn't a one-to-one relationship. A includes B but B is not all of A.

There is a whole range out there, from people who accept the science but argue that the effects of AGW are trivial to those who deny the science, and even some who deny Relativity, Quantum Physics, and all the rest.

 

[TrueSceptic]

However, since at least the seventies, the general prediction has been one of global warming (the global cooling prediction was always from a minority). If you follow the long-term trend since then, global warming has indeed happened. Could you explain to me how that constitutes a 'miss'?

Connolley, Fleck, and Peterson have followed that up with a paper. You can get it for free.

 

[Spud1k]

Connolley, Fleck, and Peterson have followed that up with a paper. You can get it for free.

Thanks for the link. Although I still like the 'whack-a-mole' analogy.

 

[lomiller]

Why assign that feedback role to CO2? Why not water vapour? Why not methane?

When you define your inputs and outputs something either is or is not a feedback factor. CO2 is a feedback factor because it warms the planet, but is itself in part a function of the planets temperature.

Water vapor is also a feedback factor, but the amount of water vapor in the atmosphere reaches it’s end state in a matter of days or weeks. This makes it almost impossible to use it as a forcing, because if you were to artificially raise the amount in the atmosphere it would be back to normal within a few weeks.

Why not methane?

Methane is taken into consideration, we just release a lot more CO2

Why not factor X?

Why didn’t Newton go looking for another explanation for gravity once he found one that worked? Science can never prove that there isn’t some mysterious “factor x” that is “the real explanation”. All you can do is pick the most likely solution from the available candidates, which becomes easy where there is only one solution that offers adequate explanations.

Logical but this still begs the question - why assume a significant role for CO2 at all?

Conservation of energy demands it. If you allow energy in, as CO2 does, and you don’t allow it to get back out, which CO2 also does temperature inside the system must increase.

 

[CapelDodger]

Really?

Forcings like massive deforestation and (as mentioned above) large scale aerosol formation (from coal burning) surely aren't relevant when we're discussing the paleo-climatic data because they didn't happen before.

True, but palaeoclimatic data is relevant today, because things that were happening then are happening now. That includes increasing CO2, decreasing albedo, and melting permafrost. It takes sophisticated techniques and equipment to separate out the individual effects but it can be done with fair accuracy. The combined impact is easier to detect.

I'm sorry if I'm being a bit contrary but it’s just we’re butting up against the part of the AGW hypothesis that I find the most difficult. In the past CO2 has always been the bit player in the game. The earth warmed in the presence of ‘normal’ CO2 levels and then later cooled in the presence of ‘high’ CO2. Other forcings, be what they may, overwhelmed the CO2 effect. Now we are hypothesising that CO2 is the 500lb gorilla in the room.

To get a good prediction of what's likely to happen in current circumstanes we need to stick to the fairly recent past - the last few hundred thousand years or so. Climate history is pretty regular over that timescale, the Sun has remained much the same as have Earth's orbital and rotational features, and continents haven't moved significantly. CO2 has stuck to a small range, ~180-310ppm.

Far from playing a minor role in explaining the ice-age cycle, CO2 was the star. The Milankovich cycles - regular oscillations in the Earth's orbit and axial tilt - don't provide enough energy to explain deglaciation, even with the positive albedo feedback. So scientists were stumped. The signal is obvious in the data, but the mechanism remained obscure.

Until it was recognised that warmer oceans hold less CO2. As oceans warmed they released CO2; as they cooled, they absorbed it. The mystery positive feedback. Work the numbers and sure enough, problem solved.

I’m not saying the idea is wrong - I’m just saying my natural sceptical side struggles with the concept.

My sceptical side (which is pretty much the only side I've got) doubted that we could materially affect climate, but I never doubted the science. I just didn't think it would amount to much. (I was raised in the post-Enlightenment science tradition that big changes happen gradually and that Mankind should get over itself.) Since then (well over thirty years ago) I have seen it have a material effect on climate.

BTW- Shouldn’t you be asleep??

When the nights draw in I enter my nocturnal phase .

 

[CapelDodger]

Thanks for the link. Although I still like the 'whack-a-mole' analogy.

It works on so many levels .

It is just a silly game, really. The ageing moles that keep popping-up are hardly life-threatening; nobody that matters ever paid them any attention. Many have pretended to, of course. And neither Inhofe nor Bush ever mattered, any more than Joe Public does.

The truth is that the world is not ordered in a way that can cope with this problem. The mechanisms aren't in place. Not even the national mechanisms to cope with climate change are in place because it's a new problem. The world is ordered to deal with the established problems concerning war, trade, finance, and the freedom of the seas. Which leaves it perfectly placed to address the complications of an unfrozen Arctic Ocean, but incapable of influencing the melting.

 

[CapelDodger]

I appreciate the support but unfortunately I have to disagree with you two also.

It's not support; they're trying to ingratiate themselves. You have the right instincts, though.

The problem is that I am an amateur. There’s thousands of scientists working in the field that back the CO2 mediated warming idea whole heartedly.

It’s ludicrous to assume they’re all either wrong, misguided or just riding the bandwagon.

The hugely more logical premise is that I am simply ill educated in this matter.

I’m working on becoming more educated which will, hopefully, ease my disquiet with this aspect of the hypothesis. It hasn't yet however.

This is where you're not at all like AussieThinker or mhaze. They know what they believe, and think a question is an answer. Their beliefs are hazy in the extreme, but their disbelief is crystal-clear - that AGW is a problem. Whatever happens, they will cling to that disbelief.

 

[CapelDodger]

It seems we're very much on the same page.

I think you're wrong there.

It’s comforting to know I’m not the only one.

Be particularly wary of comfort, that's my advice.

I greatly dislike the 'you're either for us or against us' type of attitude this debate often engenders and I dislike the terms 'warmer' and ‘denier’ equally.

I'd like to think it's possible to logically question some aspects of the theory without causing too much angst. After all, if the hypothesis is valid and robust it should be able to easily withstand my critical musings.

Which is why I think you're either on a different page or using a diifferent book from AussieThinker.

 

[DogB]

This is an excellent resource if you have questions.

Home page is http://www.aip.org/history/climate/

History of "why CO2" is here http://www.aip.org/history/climate/co2.htm

Have you read The Discovery of Global Warming?

Thank you both.

I do pick at this document but I find it just a bit superficial. It’s wonderful discussion of the history of the hypothesis but it’s less useful as a discussion of the current state of play.

 

[DogB]

It's not assumed, it's been known for a long time and it comes down to some very basic physics. The sun emits most of its energy in the visible and UV while the earth emits in the IR due to their respective temperatures and resulting blackbody functions. Carbon dioxide is a strong absorber in the IR and a weak one in the visible and UV, so makes a very good greenhouse gas. Quantifying how much upwelling heat energy CO2 traps in the atmosphere (preventing it being lost to space) is a fairly straightforward calculation. If there was no carbon dioxide in the atmosphere, the world would be a significantly colder place and conversely, if we continue to get more, it'll get warmer.

Upshot is that you can predict a big chunk of long-term warming from increases in CO2 alone; according to the best calculations, there is no bigger contribution to the current warming. The temperature increase lags behind the concentration increases because of the earth system's heat capacity (mainly in the water in it). There's also some variation due to ocean currents, but the overall trend remains.

A neat summary statement but let me ask one question - can you give me an exact figure as to what percentage of the current greenhouse effect is caused by CO2?

Of the top of my head I've seen figures from about 5% up to about 25%. What's your thoughts?

 

[DogB]

Paleo-climatic behaviour on its own is of highly limited predictive use, given that there were no people back then. It's very disingenuous to claim the whole interglacial CO2 and temperature plot proves CO2 causing climate change. That's not to say the trend isn't significant; it points to a potentially very serious feedback mechanism. But the two should never be confused and there are people on both sides who are guilty of that.

Agree absolutely.

 

[CapelDodger]

A neat summary statement but let me ask one question - can you give me an exact figure as to what percentage of the current greenhouse effect is caused by CO2?

Of the top of my head I've seen figures from about 5% up to about 25%. What's your thoughts?

It's not important what proportion is directly attributable to CO2, as opposed to CO2 and feedbacks. The crucial point is that CO2 is the initial cause of current global warming.