312 replies to this topic

[Solar Sausage]

BornFromTheVoid, on 22 January 2012 - 11:19 , said:

It's often mentioned on here how nobody ever changes their stance and how the arguments just inevitably go round in circles. Well... since I first joined this forum my thinking on AGW has changed drastically.
Up until about the age of 20 (now 23) I did believe that it was all a huge conspiracy based around cutting off the supply of oil to poorer nations so there would be more for us. I got taken in by much of the propaganda, villainising climate scientists, the peer review system and even found it funny that so many people had been taken in by such obvious twisted nonsense. The warming could be accounted for by the UHI effect and as the Arctic is losing ice, Antarctica is gaining it, so everything is still ok. The LIA and the cooling between the 40s and 70s balanced the MWP and our current warming. I felt I had all bases covered and no phony "scientific papers" could convince me otherwise
Then through work I did in Uni, mostly from 2nd year on, which necessitated reading the actual peer reviewed work and developing a basic understanding of it, things began to change...
Meeting many folk that were involved in the research, even in the IPCC reports and how they're always so determined to get the most accurate data and results possible, even when it goes against what they expect.
Learning that even in a warming world, natural variation still exists and isn't evidence of CO2 having no impact.
Realising that the scientific community have people that specialised in particular areas of atmospheric and climate studies, having devoted decades in developing their expertise, who take no notice of the keyboard scientist who believes he's found a huge loophole in something after spending a few hours on wikipedia! But of course, this fellow types up his "revelation" in a manner that's simple for others to understand and often skips any complexities and because it's easier to follow it than to go through the actual literature on the subject, people believe it, as I once did.
Essentially, the more I learned about the actual science as opposed the the rhetoric and propaganda, the more I trended towards the Pro-AGW camp. I don't believe all the dire predictions made and I don't think it's as big a disaster as it's made out to be. I also think natural variation still plays a larger role than many accept, but that's more of a feeling than anything.
I still find it annoying though how we can't watch a nature show any more without having the dangers of AGW drilled into our heads. Or how newspapers frequently publish sections on how the planet will be near lifeless in just a few hundred years because if CO2, as if it's scientific fact. I equally find it annoying how the term "climate sceptic" is used for practically anybody, because of the PC bull***t surrounding the word "denier".

Anywho, I just though I'd say that because, not everyone has entrenched views, despite what most people on here think. I'd like to think I would change my views again if faced with enough countering evidence and will continue to leave my mind open to genuine scientific work.
Apologies for not being as eloquent as many of the posters on here, end of rant

I've changed my opinion too. I was (almost) as sceptical as LG, at one time...

[jethro]

I've changed my mind too - I came to all this with an absolute acceptance that the debate and science were all settled and that we were destined to be a drought ridden, almost Med-like country in the future.

[pottyprof]

I changed my mind when I saw a film. Can't remember who was in it but it was one of those films where you just had to accept everything in it. I think it was called "The Day After Tomorrow". There was another film about a preacher who told everyone to blindly follow him and ask no questions but it wasn't quite my cuppa...

[Devonian]

I learnt about the greenhouse effect and what we might do to it many, many years ago - 80's I think. I can't remember a time when I didn't think the science and evidence shows CO2 doubling will cause a ~1C warming. I also can't see good reason to think feedbacks will add 1-5 (more likely 2-4)C warming effect for a CO2 doubling.

Do I think this is future certain? I think it's very likely. If the evidence changes I'd change my mind - so far it hasn't.

[Boar Wrinklestorm]

Devonian, on 30 January 2012 - 17:23 , said:

If the evidence changes I'd change my mind - so far it hasn't.

I am curious enough to ask 'what evidence?'

Whilst I am conducting self-flagellation to myself strongly enough to beat the cynicism, I can't help but read this as 'I will change my mind when black ceases to be black and becomes white' I really cannot understand how one can reach such a conclusion.

I'll see if I can explain what I mean. We have the natural world and we think that the natural world is governed by all sorts of laws; a collection of some of those laws requires the CO₂ molecule to be a greenhouse gas - furthermore that the Earth's atmosphere appears to act like a greenhouse is demonstrable by measuring what temperature the Earth would be at if we don't factor such things in and observing the difference. These things have been known about for at least 100 years, some of the laws have withstood scrutiny in a proper scientific manner for much much longer.

By knowing such things we can plug in all the knowns and create a model - as best we can. The same people who made the model then test it against historical time series to see if it replicates what happened in the past. Mainly, they all do. Incidentally, would you want the drug company producing a new cancer killing pill to test it themselves? How about the safety of your car by the firm that manufactured it? If we care about children not dying from cancer or not being mashed up in cars - why do we not care about what happens to the third world (of where there are lots of little children) enough to insist on rigorous testing for climate models by other people? Why do we not care about an environment - a vitally important living breathing biosphere that we must share and pass onto future generations - enough to insist that climate models, like other technological feats of humankind, must be tested by a double-blind strategy?

That's by the by. And it should keep you up at night.

Anyway, the same laws are put together into a computer system, tested against the past, and then extrapolated into the future. Let's review one of the models efficacy,



From, here, with satellite record superimposed.

It does what it says on the tin - it uses the laws of physics to measure a historical record. What it doesn't do is predict the future. At all; the measured record is below the minimum temperature - it is oodles out. For sure improvements have been made - but, crucially, it's still the same laws of physics deep down in the machine. Most climate models are similar you gather your laws of physics, combine then into a program, press go, and then tweak your assumptions until it matches the past. That's why the IPCC has at least a 400% range on it's predicted temperature in 2100. So, at least, it can say it got it right.

I must therefore assume that since the laws of physics are unlikely to change, and that the historical record is, well, the historical record, and that is the only evidence in play here, that you are effectively telling us all that only when black becomes white, and white becomes black will you change your view.

Which is never.

Edited by Boar Wrinklestorm, 16 February 2012 - 14:33 .

[songster]

http://www.realclima...ta-comparisons/

Covers this quite nicely. The 1988 Hansen paper used a value of 4.2 degrees C for climate sensitivity - it's now believed to be about 3 degrees C. Once you adjust for this, the forecast agrees with measurements to within the limits of accuracy. Note that in the real world, emissions have been running slightly below Hansen's scenario B in the 1988 paper.

[loafer]

Interesting.

I wonder if anyone has done a graph showing how estimates of sensitivity to CO2 have changed over the years and whether that trend is likely to continue or reverse?

[songster]

Essentially they've started as a wide scatter and converged somewhat. Wikipedia has a reasonable overview:
http://en.wikipedia....ate_sensitivity

[loafer]

Thanks.

The Three Degrees section appears to contradict the use of 4.2 degrees, vis;


Three degrees as the consensus estimate

A committee on anthropogenic global warming convened in 1979 by the National Academy of Sciences and chaired by Jule Charney^[10] estimated climate sensitivity to be 3 °C, plus or minus 1.5 °C. Only two sets of models were available; one, due to Syukuro Manabe, exhibited a climate sensitivity of 2 °C, the other, due to James E. Hansen, exhibited a climate sensitivity of 4 °C. "According to Manabe, Charney chose 0.5 °C as a not-unreasonable margin of error, subtracted it from Manabe’s number, and added it to Hansen’s. Thus was born the 1.5 °C-to-4.5 °C range of likely climate sensitivity that has appeared in every greenhouse assessment since..."^[14]
Chapter 4 of the "Charney report" compares the predictions of the models: "We conclude that the predictions ... are basically consistent and mutually supporting. The differences in model results are relatively small and may be accounted for by differences in model characteristics and simplifying assumptions."^[10]
The 1990 IPCC First Assessment Report estimated that equilibrium climate sensitivity to CO₂ doubling lay between 1.5 and 4.5 °C, with a "best guess in the light of current knowledge" of 2.5 °C ^[15]. This used models with strongly simplified representations of the ocean dynamics. The IPCC supplementary report, 1992 which used full ocean GCMs nonetheless saw "no compelling reason to warrant changing" from this estimate ^[16] and the IPCC Second Assessment Report found that "No strong reasons have emerged to change" these estimates^[17], with much of the uncertainty attributed to cloud processes. As noted above, the IPCC TAR retained the 1.5 to 4.5 °C, and the AR4 tightened it slightly to 2 to 4.5 °C with a best estimate of about 3 °C.
In 2008 climatologist Stefan Rahmstorf wrote, regarding the Charney report's original range of uncertainty: "At that time, this range was on very shaky ground. Since then, many vastly improved models have been developed by a number of climate research centers around the world. Current state-of-the-art climate models span a range of 2.6–4.1 °C, most clustering around 3 °C."<sup>[9]

Any idea why such a high figure was used, when it contradicted the "agreed consensus"?</sup>

[songster]

Because Hansen was writing a paper about his climate model, which happened to show a climate sensitivity of 4.2 degrees. As you quote, this was one of two models that collectively defined the agreed consensus, and at the time it was not known which model was right. In the 20+ years since then, it's been shown that the truth most likely lies somewhere in the middle, but higher climate sensitivities are not yet ruled out. Basically, it boils down to how much sulphate aerosols China has been emitting, and how much those have held global temperature down in the last decade or so.

Note also that in the very first paragraph describing the model (in the 1988 paper), you find this section:

"The equilibrium sensitivity of this model for doubled CO2 (315 ppmv -> 630 ppmv) is 4.2°C for global mean surface air temperature (Hansen et al. [1984], hereafter referred to as paper 2). This is within, but near the upper end of the range 3° ± 1.5°C estimated for climate sensitivity by National Academy of Sciences committees [Charney, 1979; Smagorinsky, 1982], where their range is a subjective estimate of the uncertainty based on climate-modeling studies and empirical evidence for climate sensitivity."

It's hardly some kind of grand conspiracy given that the very first act when discussing the model is to discuss the then-existing disagreements over climate sensitivity! Moreover, the sensitivity is an output of the model, not an input - it would be utterly wrong for him to arbitrarily pretend that his results didn't give a figure of 4.2 degrees.

Edited by songster, 17 February 2012 - 18:38 .

[Boar Wrinklestorm]

songster, on 16 February 2012 - 23:08 , said:

http://www.realclima...ta-comparisons/

Covers this quite nicely. The 1988 Hansen paper used a value of 4.2 degrees C for climate sensitivity - it's now believed to be about 3 degrees C. Once you adjust for this, the forecast agrees with measurements to within the limits of accuracy. Note that in the real world, emissions have been running slightly below Hansen's scenario B in the 1988 paper.

Yes, I quite agree, but this seems to be some sort of inverse fallacy of composition argument.

My point is that (in this order)

(i) We find the laws of physics
(ii) we construct computer models for (i)
(iii) We extrapolate (ii) into the future.

No one (as far as I can tell) is even pretending that we are going to be able to predict that, in Britain, the year 2025 will post a CET value of 10.0C. I don't even think people are pretending that we can do it for the world, either - since the Navier-Stokes equations can only be generally solved approximately you'd need an infinite amount of computing power to be certain of such a thing.

Back to my point: which one of the three steps will have to change for people to change their mind? Of those that I have listed, only one can change and that's the first one; which implies that one can only change their mind if one changes the laws of physics. Of course, I have left out a crucial step (for simplicity) and that's the parameterisation of the models - which is the bit that does change.

I quite accept that as a general ensemble all the models point to temperatures doing one thing: going upwards - and yet they all, it seems to me, missed the rapid reduction in temperature increase seen between 2000-2010. That's decadel variation and, in my view, that's quite a serious indictment. Particularly, as the laws of physics have yet to change. Yet.

Given a presumption that we are all not idiots, I must conclude that since the laws of physics haven't changed, it must be the models with the tinkering of the parameters that changes here in combination with an increase in computing power and reduction in scale.

Whether or not that's a good thing is up for debate, of course!

Edited by Boar Wrinklestorm, 27 February 2012 - 12:23 .

[Devonian]

Boar Wrinklestorm, on 27 February 2012 - 12:05 , said:

Yes, I quite agree, but this seems to be some sort of inverse fallacy of composition argument.

My point is that (in this order)

(i) We find the laws of physics
(ii) we construct computer models for (i)
(iii) We extrapolate (ii) into the future.

No one (as far as I can tell) is even pretending that we are going to be able to predict that, in Britain, the year 2025 will post a CET value of 10.0C. I don't even think people are pretending that we can do it for the world, either - since the Navier-Stokes equations can only be generally solved approximately you'd need an infinite amount of computing power to be certain of such a thing.

Back to my point: which one of the three steps will have to change for people to change their mind? Of those that I have listed, only one can change and that's the first one; which implies that one can only change their mind if one changes the laws of physics. Of course, I have left out a crucial step (for simplicity) and that's the parameterisation of the models - which is the bit that does change.

I quite accept that as a general ensemble all the models point to temperatures doing one thing: going upwards - and yet they all, it seems to me, missed the rapid reduction in temperature increase seen between 2000-2010. That's decadel variation and, in my view, that's quite a serious indictment. Particularly, as the laws of physics have yet to change. Yet.

http://www.realclima...ta-comparisons/

[Boar Wrinklestorm]

Devonian, on 27 February 2012 - 17:24 , said:

http://www.realclima...ta-comparisons/

"As we stated before, the Hansen et al ‘B’ projection is running warm compared to the real world (exactly how much warmer is unclear). As discussed in Hargreaves (2010), while this simulation was not perfect, it has shown skill in that it has out-performed any reasonable naive hypothesis that people put forward in 1988 (the most obvious being a forecast of no-change). However, the use of this comparison to refine estimates of climate sensitivity should be done cautiously, as the result is strongly dependent on the magnitude of the assumed forcing, which is itself uncertain. "

Thisis better, though.

Edited by Boar Wrinklestorm, 29 February 2012 - 17:08 .

[summersnow]

shuggee, on 18 October 2011 - 11:00 , said:

For me, not agreeing with hypotheses around AGW is about having equally rigorously scientifically-based alternative theories that stack-up. Not much of that about as far as I can see - just lots of sniping and disingenuously picking selective holes in the existing theory. If there was another theory that was demonstrably able to show that AGW was nonsense - then all of the scientific community would have to sit-up and take notice and accept the new theory(ies). That's my understanding of how science works. Call me niaive....

Yes.. probably a little niaive! There are several other theories that abound but unfortunately are given no credibility through the orthodoxy of AGW science...primarily because the peer review process is contolled by proponents of the mainstream theory! T'was always thus in science and t'will remain so long as scientists have agendas. Please don't tell me scientists don't have agendas, otherwise I will be forced to use a different adjective to niaive!

Edited by summersnow, 29 February 2012 - 22:01 .

[BornFromTheVoid]

summersnow, on 29 February 2012 - 21:59 , said:

Yes.. probably a little niaive! There are several other theories that abound but unfortunately are given no credibility through the orthodoxy of AGW science...primarily because the peer review process is contolled by proponents of the mainstream theory! T'was always thus in science and t'will remain so long as scientists have agendas. Please don't tell me scientists don't have agendas, otherwise I will be forced to use a different adjective to niaive!

So there will be no presenting peer reviewed evidence to you so... what type of evidence do you accept then?

[Thundery wintry showers]

Although there is certainly some evidence of defensiveness over the scientific "consensus" I think climate scientists on the whole are more inclined to allow expression of alternative viewpoints/theories than most. After all, climate science should be about the quest to identify the truth so if the genuine sceptics can come up with scientific evidence that casts doubt on some aspects of the prevailing consensus, then it forces scientists to re-assess the situation and improve their understanding of the global climate system. Indeed a number of established climate scientists have actually said to me that they welcome having their positions questioned using scientific counter-evidence.

The real problem is when it gets political, when "is indicated if current trends continue", "is statistically likely" and "has 80% support from the multi-model ensemble" get replaced with "will", "will" and "will", and "alternative viewpoints will be considered if supported by sound scientific evidence" gets replaced with "either you're with us or you're against us- we all need to speak with one voice and, because many people don't understand probabilities we need to make it clear that the science is settled even though it isn't".

[Solar Sausage]

summersnow, on 29 February 2012 - 21:59 , said:

Yes.. probably a little niaive! There are several other theories that abound but unfortunately are given no credibility through the orthodoxy of AGW science...primarily because the peer review process is contolled by proponents of the mainstream theory! T'was always thus in science and t'will remain so long as scientists have agendas. Please don't tell me scientists don't have agendas, otherwise I will be forced to use a different adjective to niaive!

Unfortunately, most - if not all - of these other 'theories' are nothing more than conjecture. What's more, they're seldom in line with the evidence. I am a natural-born sceptic; even more so when Big Oil or Coal come up with 'theories' that seem only to justify the continued exploitation of fossil fuels - and those interests' continued profits??

[summersnow]

Solar Sausage, on 01 March 2012 - 09:34 , said:

Unfortunately, most - if not all - of these other 'theories' are nothing more than conjecture. What's more, they're seldom in line with the evidence. I am a natural-born sceptic; even more so when Big Oil or Coal come up with 'theories' that seem only to justify the continued exploitation of fossil fuels - and those interests' continued profits??

Not true! There are several very plausible theories that are simply not getting any air time because the peer review & publicity processes are so well sown up by the IPCC et al. Worse still, alternative theories are seriously maligned purely, simply because they challenge mainstream theory!

History will tell you that any version of the past is told according to the views of the story teller. That is why, we have so many very different accounts of historical events - those who have the power, basically control what becomes the most accepted version of events. This is also what also happens in science, politics, academia, law or virtually any walk of life conceivable. The "truth" is just a sideline - much more important is whose theory, team, party, gossip, arguement, sex appeal, charisma, movement, morality etc, is winning! Reputations, egos, money, power, greed, self /territorial protection/promotion....., all get in the way of establishing the truth clearly. As I stated before..."t'was always thus and t'will always be".....

Oh, and by the way.... there's every bit as much money (probably much more) associated with the funding of AGW research as there is of fossil fuel producers sponsering alternative research. Science is big business these days, and as long as this is the case, the search for the truth through science, will be compromised - be it motivated by politics, power, money or any combination of those!

If AGW theory were to be seriosly challenged, just imagine the fall out! Imagine the egg on so many VIP's faces. Imagine the reputations that might fall and imagine how many people might lose their jobs & livelihoods - not to mention the communities that are sustained by this all important issue?

Don't get me wrong, I am in 100% agreement with the sentimment that the human race is causing massive and possibly irreversible damage to our ecosystems, primarily because there are 7 billion of us on the planet, all competing for twindling resources. I don't however buy the notion AGW science is settled for a number of pretty glaring and obvious reasons.

Edited by summersnow, 01 March 2012 - 14:06 .

[Solar Sausage]

I agree with TWS; the problems start when science becomes politicized.

And indeed summersnow, AGW theory is flawed. It being a human endeavour, it is bound to be. IMO all human endeavours are flawed.

But that fact alone does not provide us with any realy coherent alternative??? Where are the credible alternatives to CO₂ induced warming? Surely if there was one WUWT would have found it by now? Once one's discounted all those silly attempts at discrediting the temperature records, that is...

[summersnow]

Solar Sausage, on 01 March 2012 - 14:49 , said:

I agree with TWS; the problems start when science becomes politicized.

And indeed summersnow, AGW theory is flawed. It being a human endeavour, it is bound to be. IMO all human endeavours are flawed.

But that fact alone does not provide us with any realy coherent alternative??? Where are the credible alternatives to CO₂ induced warming? Surely if there was one WUWT would have found it by now? Once one's discounted all those silly attempts at discrediting the temperature records, that is...

I don't think anyone worth their salt who has studied the issue would argue with the theory of "CO2 induced warming"! But the problems start after that - to name but a few....would the 90pp million extra CO2 molecules really be enough to tip the balance? Why are we making assumptions from a period of 30, possibly 100 years of warming within a period of minimum 10,000 years since the last ice age? There is alot of very valid research that complelety debunks the notion that we are now at the warmest point since the last ice age. Why does the recent temperature record nowhere near match the modelled projections? Why does the long term CO2 record always lag the temperature record by some 800 years?

The only bit that makes any sense at all is the theory that CO2 molecules can alter the radiative balance in the atmosphere, but the extra CO2 above what Dr Hansen considers "natural", constitutes such a tiny proportion of the atmosphere, that the effect must be ridiculously marginal. The rest of the assumptions that are made to do with positive feedbacks... water vapour build up, methane release etc, etc are a long, long way from being settled. Because there are so many forces of nature that we are also such a long way from fully understanding, I do not believe the very tenuous science behind this theory to be anywhere near settled - it might be possible, but it's far from settled!

Edited by summersnow, 01 March 2012 - 15:26 .