Climate Change - The Scientific Debate

Climate Change - The Scientific Debate

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plunker

542 posts

125 months

Wednesday 26th November 2014
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Variomatic said:
Yeah, sorry about the mis-counted dates, let's just pretend that a decade has 11 years - doesn't make a whole heap of difference cos using a decade was just an arbitrary choice smile

The logic behind using a rolling start date is that if there's a change point (or a relatively rapid change over a few years more likely) then using increasingly long periods which include the earlier trend will tend to obscure the change by weighting the trend with the earlier slope.



As a thought experiment, consider calculating trends along a sine curve (no, I'm NOT suggesting temperatures are following a sine) using a fixed start point.

If you happen to start at the "bottom" of the curve then the trend will increase as your end point heads towards the top, then start to decrease again towards zero as it drops down the other side, but it will never become negative, even though half the time the real trend in the data is downwards.

Similarly, if you happen to start at the top of the curve, you'll get the impression that the trend is never positive, even though the data spends exactly half its time increasing!
I see what you're saying but I don't think it matters for our purposes.

Anyway, here's what I think is a better way to go about it. Below are the yearly slope values since 1996 with 1978 as the start date.

1996: slope = 0.0122981 per year
1997: slope = 0.0143425 per year - UP
1998: slope = 0.0174034 per year - UP
1999: slope = 0.016809 per year - DOWN
2000: slope = 0.0160822 per year - DOWN
2001: slope = 0.01681 per year - UP
2002: slope = 0.0177026 per year - UP
2003: slope = 0.018367 per year - UP
2004: slope = 0.0182728 per year - DOWN
2005: slope = 0.0187763 per year - UP (maximum)
2006: slope = 0.0187474 per year - DOWN
2007: slope = 0.0185084 per year - DOWN
2008: slope = 0.0176414 per year - DOWN
2009: slope = 0.0174241 per year - DOWN
2010: slope = 0.0174248 per year - SAME
2011: slope = 0.0166401 per year - DOWN
2012: slope = 0.016108 per year - DOWN
2013: slope = 0.0157617 per year - DOWN
2014: slope = 0.0156742 per year - DOWN (provisional)

In bold is the slope with the highest value 1978-2005 (inclusive) and from there it's virtually all down, but the following two years are so close in value I'm still happy with 'around 2007' for when I think the recent downward change in the trend started. I haven't looked at the other datasets yet but so far at least it doesn't look like there's much of a case for saying it started before 2005 (edit - make that 2006).

Might as well post the graphs as well...

Linear trends 1978 to 1997 thru to 2005:



Linear trends 1978 to 2006 thru to 2014:

Edited by plunker on Wednesday 26th November 10:53

PRTVR

7,072 posts

220 months

Wednesday 26th November 2014
quotequote all
While all these charts are very nice, what proof do we have that a small part of a trace gas is having an effect? Coralation does not mean causation, as has been said before re the number of pirates and the rise in CO2.

Then we come to the pause in the rise of the temperature, I do think it it is happening, why else would they come up with the line that the missing heat is in the deep oceans,if the pause is happening then we don't even have coralation, that would make the theory false, all the charts in the world, with all there different interpretations are not going to change that.

Variomatic

2,392 posts

160 months

Wednesday 26th November 2014
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plunker said:
[...] I'm still happy with 'around 2007' for when I think the recent downward change in the trend started. I haven't looked at the other datasets yet but so far at least it doesn't look like there's much of a case for saying it started before 2005 (edit - make that 2006).
I can accept that, but I'm not sure a year or two (or even 5) either way will matter much if it continues through the next few years.

Given the amount of natural noise in the system and the, shall we say, dubious, standards of collecting the data at times (without which there'd be no need for any adjustments ever!) I don't see that there'll ever be a way to pin down any change definitively to better than "during the first decade of the 21st C (ish, give or take a few years)" biggrin

Variomatic

2,392 posts

160 months

Wednesday 26th November 2014
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PRTVR said:
While all these charts are very nice, what proof do we have that a small part of a trace gas is having an effect? Coralation does not mean causation, as has been said before re the number of pirates and the rise in CO2.
Fairly straightforward physics says that it will have an effect, and the fact it's a trace gas is actually neither here nor there. Cyanide can be fatal in doses as low as 1.5mg per kg - which in percentage terms is .00015%. Thats far more "trace" - over 2 orders of magnitude smaller - than the .04% or so of CO2 in the atmosphere but its effect can still be devastating.

If everything else stayed equal - ie: no air movement, no changes in ocean circulation, no conduction or convection of heat, no changes in TSI, no changes in other atmospheric gasses or vapours, no changes in cloud cover, no "greening" as a result of extra plant food, no albedo changes as a result of ice and so on - then we can calculate quite accurately what effect more CO2 would have, and we can demonstrate it experimentally.

But nothing else does stay the same in the real climate and it's simplistic beyond belief to try and translate those experimental results or theoretical calculations into "proof" that the same thing will happen in a system which is so complex.

So the science relies heavily on statistics, where you're quite right that correlation does not equal causation - especially where there's doubt about the chronology and any theoretical causation may operate in both directions anyway. Physics (as above) tells us that more CO2 should = higher temps and higher temps should = more CO2 due to ocean out-gassing etc. Without some form of overall negative feedback that would inevitably be an unstable system with the slightest initial change spiralling out of control.

That hasn't happened over the past several million years that we're aware of, which is pretty strong evidence for an overall negative feedback between the two. It's the strength and speed of that feedback that will ultimately determine whether or not burning dinosaurs is a problem.

QuantumTokoloshi

4,161 posts

216 months

Wednesday 26th November 2014
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An interesting point made when listening to a podcast about ice ages, is the point that the Earth through 70% of it's history has been in an ice age condition, this interglacial period is actually, over planetary timescales, an aberration.

http://www.bbc.co.uk/programmes/b01qjj99

In the light of this, surely global warming of the planet is not a negative from a human point of view. A planet largely covered in 1 or 2 km thick ice is not conducive to large scale human habitation ?

PRTVR

7,072 posts

220 months

Wednesday 26th November 2014
quotequote all
Variomatic said:
PRTVR said:
While all these charts are very nice, what proof do we have that a small part of a trace gas is having an effect? Coralation does not mean causation, as has been said before re the number of pirates and the rise in CO2.
Fairly straightforward physics says that it will have an effect, and the fact it's a trace gas is actually neither here nor there. Cyanide can be fatal in doses as low as 1.5mg per kg - which in percentage terms is .00015%. Thats far more "trace" - over 2 orders of magnitude smaller - than the .04% or so of CO2 in the atmosphere but its effect can still be devastating.
The mechanism by which cyanide effects the body are well known, but what we are talking about is basically heat retention, imagine a greenhouse, then we add more glass but only at a small fraction of .04 of the total area, how much extra heat will be retained?
With heat retention concentrations matter, with CO2 the best that could be expected is a minute delay in cooling, unless you know of some magical property that CO2 has,
Then how do you distinguish the small change against the background of larger influences.
( take for example the variations of the sun )
At times it appears that science has been turned on its head, we have the results we want, now how do we beat the real world results into agreeing with the agreed end conclusion. Science it is not.

Variomatic

2,392 posts

160 months

Wednesday 26th November 2014
quotequote all
PRTVR said:
The mechanism by which cyanide effects the body are well known, but what we are talking about is basically heat retention, imagine a greenhouse, then we add more glass but only at a small fraction of .04 of the total area, how much extra heat will be retained?
With heat retention concentrations matter, with CO2 the best that could be expected is a minute delay in cooling, unless you know of some magical property that CO2 has,
Then how do you distinguish the small change against the background of larger influences.
( take for example the variations of the sun )
At times it appears that science has been turned on its head, we have the results we want, now how do we beat the real world results into agreeing with the agreed end conclusion. Science it is not.
The mechanism by which CO2 causes warming is also well known and accepted (even by serious AGW sceptics). It can and does operate even at trace quantities and the magnitute of its effect in a laboratory can be predicted, measured and confirmed perfecty adequately.

But, in the real climate, it doesn't operate in laboratory conditions and that's why the point about distingusinhing it from all the other external influences and feedbacks in the system itself, is the nub of the problem.

Incidentally, I totally agree that it often seems as if the conclusion has come first, with the data tortured until it fits. Which is how the recent warming appears to have got into the deep, unmeasured, oceans without showing any sign of passing through the shallower, measured, oceans on its way there. But you're not meant to ask inconvenient questions wen dealing with Faith wink

PRTVR

7,072 posts

220 months

Wednesday 26th November 2014
quotequote all
Variomatic said:
PRTVR said:
The mechanism by which cyanide effects the body are well known, but what we are talking about is basically heat retention, imagine a greenhouse, then we add more glass but only at a small fraction of .04 of the total area, how much extra heat will be retained?
With heat retention concentrations matter, with CO2 the best that could be expected is a minute delay in cooling, unless you know of some magical property that CO2 has,
Then how do you distinguish the small change against the background of larger influences.
( take for example the variations of the sun )
At times it appears that science has been turned on its head, we have the results we want, now how do we beat the real world results into agreeing with the agreed end conclusion. Science it is not.
The mechanism by which CO2 causes warming is also well known and accepted (even by serious AGW sceptics). It can and does operate even at trace quantities and the magnitute of its effect in a laboratory can be predicted, measured and confirmed perfecty adequately.

But, in the real climate, it doesn't operate in laboratory conditions and that's why the point about distingusinhing it from all the other external influences and feedbacks in the system itself, is the nub of the problem.

Incidentally, I totally agree that it often seems as if the conclusion has come first, with the data tortured until it fits. Which is how the recent warming appears to have got into the deep, unmeasured, oceans without showing any sign of passing through the shallower, measured, oceans on its way there. But you're not meant to ask inconvenient questions wen dealing with Faith wink
Have the laboratory tests been carried out with a minute increase in CO2 ?, the tests I have seen have had the whole container full of CO2 against a similar container full of air, if you have a link to any that would be great.

Variomatic

2,392 posts

160 months

Wednesday 26th November 2014
quotequote all
PRTVR said:
Have the laboratory tests been carried out with a minute increase in CO2 ?, the tests I have seen have had the whole container full of CO2 against a similar container full of air, if you have a link to any that would be great.
They don't need to be. It's perfectly ok to carry out an experiment with, say, increased concentrations to enhance an effect and make it more easily measurable if the results can be translated using maths - which they can be.

The problem with the "experiments" you see in boxes isn't the concentrations used, it's that they're done in boxes! No convection and little conduction to the "outside" and no feedbacks whatsoever to modify the effects invalidate them completely as demonsrations of how things work in the climate.

It doesn't invalidate them as demonstrations of the basic radiative properties of CO2, but that's rarely what they're "sold" as. Wen these things are dragged up by AGW proponents there's never any mention of the confounding factors which can make the results entirely different in te atmosphere even though the CO2 will act in the same way.

That shows either scientific illiteracy if those presenting them don't realise the limits of the results, or gross scientific fraud if they realise but don't say. I have no idea which it is btw wink

rovermorris999

5,195 posts

188 months

Thursday 27th November 2014
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Variomatic said:
They don't need to be. It's perfectly ok to carry out an experiment with, say, increased concentrations to enhance an effect and make it more easily measurable if the results can be translated using maths - which they can be.
That's true if the effect is directly proportional. I have no idea whether it is or isn't but it wouldn't surprise me if different mechanisms kicked in at very low or high concentrations. An example would be a buffered solution. You can add acid or alkali drop by drop and the ph doesn't change until a tipping point is reached.

hairykrishna

13,158 posts

202 months

Thursday 27th November 2014
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The theoretical basis for IR absorption bands is very strong. It's also been measured extremely accurately for a massive range of conditions including directly in the atmosphere. We have codes which model IR transport for different conditions totally reliably. This was all done long before anyone cared about the climate.

The uncertainty in that part of the science is, for all practical purposes, zero.

plunker

542 posts

125 months

Thursday 27th November 2014
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hairykrishna said:
The theoretical basis for IR absorption bands is very strong. It's also been measured extremely accurately for a massive range of conditions including directly in the atmosphere. We have codes which model IR transport for different conditions totally reliably. This was all done long before anyone cared about the climate.

The uncertainty in that part of the science is, for all practical purposes, zero.
What, you mean it isn't based on shining an infra-red lamp at a flask of CO2 with a thermometer in it and then doing some maths?


clyffepypard

74 posts

172 months

Thursday 27th November 2014
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hairykrishna said:
The theoretical basis for IR absorption bands is very strong. It's also been measured extremely accurately for a massive range of conditions including directly in the atmosphere. We have codes which model IR transport for different conditions totally reliably. This was all done long before anyone cared about the climate.

The uncertainty in that part of the science is, for all practical purposes, zero.
So where is the predicted tropospheric hot-spot if the science uncertainy is zero.

Variomatic

2,392 posts

160 months

Thursday 27th November 2014
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clyffepypard said:
So where is the predicted tropospheric hot-spot if the science uncertainy is zero.
Hairy is right that the science of IR absorption bt CO2 is very well understood.

What he either doesn't seem to grasp (being nice to him) or intentionally chooses not to mention (being more cynical) is that you simply can't take known theoretical results like that and apply them to a system like the climate, where there are so many confounding factors such as completely independent variables (some of which we may not even know about) and feedbacks.

Some of those feedbacks, even though we know about them, we don't even know if they're a nett positive or negative effect. And some of those feedbacks (that we don't know the direction of) may also feed back themselves to affect the concentration of CO2 in a positive or negative way - higher temsp will increase outgassing from oceans (scientifically known) but will also - within unknown limits - increase plant growth and, hence, uptake of CO2 from the air. Which is dominant has only been looked at by models which are simplistic, incomplete, and (no matter what the bleatings of the IPCC suggest) have a really rather bad track record.


So, while he's right to say that the physics of IR absorption are known, it's either woefully naive or fraudulently dishonest to suggest that theoretical result can be extrapolated to knowing the result on the climate.

plunker

542 posts

125 months

Thursday 27th November 2014
quotequote all
Variomatic said:
clyffepypard said:
So where is the predicted tropospheric hot-spot if the science uncertainy is zero.
Hairy is right that the science of IR absorption bt CO2 is very well understood.

What he either doesn't seem to grasp (being nice to him) or intentionally chooses not to mention (being more cynical) is that you simply can't take known theoretical results like that and apply them to a system like the climate, where there are so many confounding factors such as completely independent variables (some of which we may not even know about) and feedbacks.

Some of those feedbacks, even though we know about them, we don't even know if they're a nett positive or negative effect. And some of those feedbacks (that we don't know the direction of) may also feed back themselves to affect the concentration of CO2 in a positive or negative way - higher temsp will increase outgassing from oceans (scientifically known) but will also - within unknown limits - increase plant growth and, hence, uptake of CO2 from the air. Which is dominant has only been looked at by models which are simplistic, incomplete, and (no matter what the bleatings of the IPCC suggest) have a really rather bad track record.


So, while he's right to say that the physics of IR absorption are known, it's either woefully naive or fraudulently dishonest to suggest that theoretical result can be extrapolated to knowing the result on the climate.
HK didn't suggest that though did he - he was quite specific and to the point.

To be honest, I don't think you were informing PRTVR very well by talking about lab experiments and their inadequacies (another straw man) so HK's input was quite timely.

hairykrishna

13,158 posts

202 months

Thursday 27th November 2014
quotequote all
Variomatic said:
What he either doesn't seem to grasp (being nice to him) or intentionally chooses not to mention (being more cynical) is that you simply can't take known theoretical results like that and apply them to a system like the climate, where there are so many confounding factors such as completely independent variables (some of which we may not even know about) and feedbacks.
I was talking about the IR absorption properties of gases. I would have thought that was obvious from my post. These absolutely can be applied to the atmosphere.

Variomatic said:
It's not a matter of self righteousness, it's a matter of not having valid statements twisted into invalid ones in order to "rebut" them. Something that happens far too often when this subjet is discussed, and something that I'll happily pick up either side on if i see it because it adds nothing to the discussion except for point-scoring and animosity.

In short, it ain't clever to rebut a point that no-one made in the first place.

hairykrishna

13,158 posts

202 months

Thursday 27th November 2014
quotequote all
clyffepypard said:
So where is the predicted tropospheric hot-spot if the science uncertainy is zero.
The science uncertainty I was talking about was specifically that of radiation transport in gases. Not the effect of changing IR absorption on climate.

Regarding troposphere temperatures - is this a question that comes out from work in the current literature? Or are you asking about disagreements between models and satellite data from about 20 years ago?

Variomatic

2,392 posts

160 months

Thursday 27th November 2014
quotequote all
plunker said:
HK didn't suggest that though did he - he was quite specific and to the point.

To be honest, I don't think you were informing PRTVR very well by talking about lab experiments and their inadequacies (another straw man) so HK's input was quite timely.
My point to PVRT (which, as far as I can see reasing back was perfectly clear) was that we do know the radiative properties of CO2 and we can test them by experiment in the laboratory, so querying that part of "the science" is misguided because it is sound.

What we can't do is transfer those properties i any meaningful way to the real-world atmosphere - regardless of what the believers say - because there are too many unknown factors which will alter the effect in unknown ways.

Unfortunately, questioning the basic properties of gasses gives certain elements a perfect excuse for ad-hom "science denier" type attacks which allows them to deflect from the fact that the schoolroom physics does not translate to the real, chaotic, world.


hairykrishna said:
I was talking about the IR absorption properties of gases. I would have thought that was obvious from my post. These absolutely can be applied to the atmosphere.
Sadly, you inserted your comment arbitrarily at a point in the discussion which was talking about real-world appplication of the physics, leaving an impression that you were saying the real-world effects of that physics are well established and uantified in the same way as the basic physics is.

Seeing as that claim that we understand "well enough" how the physics affects the climate is absolutely central to the entire CAGW theory, if that's not what you intended to suggest then welcome to The Deniers smile

plunker

542 posts

125 months

Thursday 27th November 2014
quotequote all
Variomatic said:
plunker said:
HK didn't suggest that though did he - he was quite specific and to the point.

To be honest, I don't think you were informing PRTVR very well by talking about lab experiments and their inadequacies (another straw man) so HK's input was quite timely.
My point to PVRT (which, as far as I can see reasing back was perfectly clear) was that we do know the radiative properties of CO2 and we can test them by experiment in the laboratory, so querying that part of "the science" is misguided because it is sound.

What we can't do is transfer those properties i any meaningful way to the real-world atmosphere - regardless of what the believers say - because there are too many unknown factors which will alter the effect in unknown ways.

Unfortunately, questioning the basic properties of gasses gives certain elements a perfect excuse for ad-hom "science denier" type attacks which allows them to deflect from the fact that the schoolroom physics does not translate to the real, chaotic, world.
Schoolroom physics?

A great deal more is known about the physics of greenhouse gases in the atmosphere than you're implying.

That's what HK is saying to you and that's what I was saying to you when I said you aren't informing PRTVR very well by going on about the inadequacies of basic lab experiments vs real world - that's a straw man because what's known about the effects of CO2 isn't based on basic lab experiments.



Variomatic

2,392 posts

160 months

Friday 28th November 2014
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plunker said:
Schoolroom physics?

A great deal more is known about the physics of greenhouse gases in the atmosphere than you're implying.

That's what HK is saying to you and that's what I was saying to you when I said you aren't informing PRTVR very well by going on about the inadequacies of basic lab experiments vs real world - that's a straw man because what's known about the effects of CO2 isn't based on basic lab experiments.
No, ir's not a strawman.

The physics of CO2 absorption of IR are very well established. Those are the same within the lab or within the atmosphere - because they're based on sound physics.

What is absolutely not known to any meaningful extent is how that basic physics translates to effects on the climate, given te myriad confounding factors in the real world.

In case you hadn't noticed, I was actually agreeing with both you and hairy (and the whole AGW movement) by correcting PVRT about is questioning of the "basic physics" of CO2 absorption.

If you feel a need to disagree with me about agreeing with you then I'm really not sure what your position is other than to automatically disagree with anyone who doesn't hold to your total belief system.

That's neither productive nor scientific and effectively ends any point in this discussion.

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