Is Anthropogenic Global Warming Falsifiable?

[Blake]

Not sure whether to put this here or in GQ, but I figure it’ll end up here anyway, so I’ll phrase it as debate.

So, for background I’ll refer you to Popper’s essay on falsifiability. Basically the Popperian standad of science is “the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.” IOW a theory is only scientific if “the theory is incompatible with certain possible results of observation” Or to put it another way the theory should predict something, and if that prediction fails then the theory is considered wrong. A theory that doesn’t do this isn’t science.

Now there are many other non-Popperian definitions/standards of science. But the Popperian definition is the most widely accepted. It is also the one with the greatest utility when trying to separate psuedoscience such as Astrology form real science, and this is why it is invariably the definition used in the various court cases concerning Intelligent Design. So I’m not looking for debate on the Popperian definition itself. For the purposes of this debate I’m accepting that the Popperian definition is useful and accurate.

So, what possible results of observation are incompatible with the theory of AGW?

Not the fact that the temperature is increasing in line with CO2 emmisions.

The increase in temprature is the very observation that AGW theory was created to explain. For the purposes of this discussion I want to accept as axiomatic that small-c climate change is occurring. Temperatures are rising, they have been rising steadily since since C1860 and more erratically since C1600.

Not the link to CO2 levels. Atmospheric CO2 levels have been rising in a nearly perfect exponential fashion since C1600 and show little to no evidence of recent increases. Moreover historicallly CO2 increases followed temperature increases, just as they have in the present warming event. Cause can't follow effect. this isn't to say that CO2 doesn't cause warming, but the mechanism by which CO2 levels increased started in 1600, well before the invention of the internal steam engine so if a lack of correlation falsifies AGW then it has already been falsified. Now if someone had predicted that temperatures would continue to rise paralleling CO2 increases that would be acceptable of course. But the models don't; do that. they all work on complex interactions. that's not a bad thing in itself, but it does mean that the mere fact that CO2 levels increase roughly inline with temperature isn't a falsifiable prediction because if they don't the hypothesis isn't rejected. For example, for the last 11 years temperatures haven’t risen at all despite record atmospheric levels of CO2.

What is being debated is the theory that the rises are anthropogenic. The IPCC notes that all the rises up to 1950 were just as likely to be natural as anthropogenic. So I am working here with a null hypothesis that human activities have made no detectable difference to global temperature. IOW that temperatures had been rising up to 1950 as a result of natural factors and have continued to rise as a result of natural factors.

Now I understand this is a complex field and relationships aren’t simple. But the question isn’t why predictions can’t be made. The question is whether predictions have been made. It’s not science if the theory isn’t incompatible with certain possible results of observation.


In previous threads people have suggested that Hansen’s 1988 models qualify as falsifiable predictions. The problem I have with them is that they predict everything. They cover such a wide range of scenarios. If the temperature trend had continued unchanged then model scenario B would have predicted it. And if temperature had increased scenario A would have predicted it. And if temperatures had levelled off then scenario C would have predicted it. IOW the model predicted any plausible outcome that might have occurred if global temperature changes were purely natural. To paraphrase Popper “I could not think of any climate behavior which could not be interpreted in terms this model”. And as Popper notes this is not scientific. A theory that predicts everything predicts nothing. Hansens models are not incompatible with any possible results of observation that we might get if climate change is entirely natural.

Lest you think I don’t understand how complex this is, I’ll let you in on a bit of my autobiography. I’m an ecologist/plant physiologist. I’ve been employed as a scientist to study climate change, and I’ve been published on the subject in Global Change Biology, the premier journal in my field. I’ve collected data and constructed models. I understand that it’s difficult. But I also know that I have never needed to engage a hypothesis that wasn’t falsifiable. Even though most of my work has been conducted in natural ecosystems where control is impossible I know that you can always construct falsifiable hypotheses if you are engaging in good science.


So I ask those of you who accept AGW and who believe it is good science: what evidence could I show you that would lead you to reject AGW? Obviously a prolonged period of cooling despite an ioncrase in atmospheric CO2 levels won’t do it. In the last 10 years global temperatures have been stable, and for the past five years the temperature trend has actually been negative fig 1. We’ve already had recent papers stating that temperature may not increase over the next decade, but nobody is predicting that they must decrease. IOW this isn’t itself a falsifiable prediction. In fact this makes me even more skeptical of AGW as a theory. It really does predict everything, since it can be used to predict prolonged periods of global cooling as well as periods of global warming.

To pre-empt questions of what evidence I would accept that would lead me to accept AGW. I’ll accept it when someone can show me a peer reviewed paper that 1) Provides replicable evidence for its conclusions 2) Presents a prediction that will lead to AGW being rejected. 3) Analyses observations and concludes, based on a previously acknowledged statistical test, that there is a >95% chance that human activities have produced a measurable effect on global climate. Not a 95% estimate but an actual 95% probability. That’s the evidence that I require to accept everything else as science. AGW isn’t allowed a lowered standard.

To pre-empt comparisons with evolution and other similarly complex topics that have been proved by a body of evidence, I’ll point out that Darwin gave a falsification 100 years ago: if any structure can be shown to exos that couldn’t; derive form previous structures. To which I will add that if anyone can show me a bird fossil in pre-Cambrian sediments or show me that dog DNA is less similar to human DNA than to jellyfish DNA I’ll also consider it falsified. It isn’t any harder to produce falsifiable predictions for theories built on a body of evidence. It’s usually much easier.

So the GQ and the spark for debate is: what evidence could I show you that would lead you to reject AGW? One again I’d like to stress that the question isn’t why falsifiable predictions can’t be made. The question is whether falsifiable predictions have been made. According to Popper it’s not science if the theory isn’t incompatible with certain possible results of observation. So what possible results of observation could I show you that would be incompatible with AGW?

[Sage Rat]

Originally Posted by Blake

what evidence could I show you that would lead you to reject AGW?

Any evidence for any theory which more accurately recreates the historical climate and conditions of things in modern times, would do. That happens to be the standard for all theories.

The only challengers to the greenhouse gas based climate change theory that I've seen are that the sun is hotter/cyclical or that scientists/the UN is falsifying data. The former really doesn't seem to be based on anything but a couple of very short term graphs that have been mangled, and the latter requires a conspiracy of greater size than has ever been seen on the planet since the Illuminati.

[Lobohan]

Originally Posted by Blake

Not sure whether to put this here or in GQ, but I figure it’ll end up here anyway, so I’ll phrase it as debate.

So, for background I’ll refer you to Popper’s essay on falsifiability. Basically the Popperian standad of science is “the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.” IOW a theory is only scientific if “the theory is incompatible with certain possible results of observation” Or to put it another way the theory should predict something, and if that prediction fails then the theory is considered wrong. A theory that doesn’t do this isn’t science.

Now there are many other non-Popperian definitions/standards of science. But the Popperian definition is the most widely accepted. It is also the one with the greatest utility when trying to separate psuedoscience such as Astrology form real science, and this is why it is invariably the definition used in the various court cases concerning Intelligent Design. So I’m not looking for debate on the Popperian definition itself. For the purposes of this debate I’m accepting that the Popperian definition is useful and accurate.

So, what possible results of observation are incompatible with the theory of AGW?

Not the fact that the temperature is increasing in line with CO2 emmisions.

The increase in temprature is the very observation that AGW theory was created to explain. For the purposes of this discussion I want to accept as axiomatic that small-c climate change is occurring. Temperatures are rising, they have been rising steadily since since C1860 and more erratically since C1600.

Not the link to CO2 levels. Atmospheric CO2 levels have been rising in a nearly perfect exponential fashion since C1600 and show little to no evidence of recent increases. Moreover historicallly CO2 increases followed temperature increases, just as they have in the present warming event. Cause can't follow effect. this isn't to say that CO2 doesn't cause warming, but the mechanism by which CO2 levels increased started in 1600, well before the invention of the internal steam engine so if a lack of correlation falsifies AGW then it has already been falsified. Now if someone had predicted that temperatures would continue to rise paralleling CO2 increases that would be acceptable of course. But the models don't; do that. they all work on complex interactions. that's not a bad thing in itself, but it does mean that the mere fact that CO2 levels increase roughly inline with temperature isn't a falsifiable prediction because if they don't the hypothesis isn't rejected. For example, for the last 11 years temperatures haven’t risen at all despite record atmospheric levels of CO2.

What is being debated is the theory that the rises are anthropogenic. The IPCC notes that all the rises up to 1950 were just as likely to be natural as anthropogenic. So I am working here with a null hypothesis that human activities have made no detectable difference to global temperature. IOW that temperatures had been rising up to 1950 as a result of natural factors and have continued to rise as a result of natural factors.

Now I understand this is a complex field and relationships aren’t simple. But the question isn’t why predictions can’t be made. The question is whether predictions have been made. It’s not science if the theory isn’t incompatible with certain possible results of observation.


In previous threads people have suggested that Hansen’s 1988 models qualify as falsifiable predictions. The problem I have with them is that they predict everything. They cover such a wide range of scenarios. If the temperature trend had continued unchanged then model scenario B would have predicted it. And if temperature had increased scenario A would have predicted it. And if temperatures had levelled off then scenario C would have predicted it. IOW the model predicted any plausible outcome that might have occurred if global temperature changes were purely natural. To paraphrase Popper “I could not think of any climate behavior which could not be interpreted in terms this model”. And as Popper notes this is not scientific. A theory that predicts everything predicts nothing. Hansens models are not incompatible with any possible results of observation that we might get if climate change is entirely natural.

Lest you think I don’t understand how complex this is, I’ll let you in on a bit of my autobiography. I’m an ecologist/plant physiologist. I’ve been employed as a scientist to study climate change, and I’ve been published on the subject in Global Change Biology, the premier journal in my field. I’ve collected data and constructed models. I understand that it’s difficult. But I also know that I have never needed to engage a hypothesis that wasn’t falsifiable. Even though most of my work has been conducted in natural ecosystems where control is impossible I know that you can always construct falsifiable hypotheses if you are engaging in good science.


So I ask those of you who accept AGW and who believe it is good science: what evidence could I show you that would lead you to reject AGW? Obviously a prolonged period of cooling despite an ioncrase in atmospheric CO2 levels won’t do it. In the last 10 years global temperatures have been stable, and for the past five years the temperature trend has actually been negative fig 1. We’ve already had recent papers stating that temperature may not increase over the next decade, but nobody is predicting that they must decrease. IOW this isn’t itself a falsifiable prediction. In fact this makes me even more skeptical of AGW as a theory. It really does predict everything, since it can be used to predict prolonged periods of global cooling as well as periods of global warming.

To pre-empt questions of what evidence I would accept that would lead me to accept AGW. I’ll accept it when someone can show me a peer reviewed paper that 1) Provides replicable evidence for its conclusions 2) Presents a prediction that will lead to AGW being rejected. 3) Analyses observations and concludes, based on a previously acknowledged statistical test, that there is a >95% chance that human activities have produced a measurable effect on global climate. Not a 95% estimate but an actual 95% probability. That’s the evidence that I require to accept everything else as science. AGW isn’t allowed a lowered standard.

To pre-empt comparisons with evolution and other similarly complex topics that have been proved by a body of evidence, I’ll point out that Darwin gave a falsification 100 years ago: if any structure can be shown to exos that couldn’t; derive form previous structures. To which I will add that if anyone can show me a bird fossil in pre-Cambrian sediments or show me that dog DNA is less similar to human DNA than to jellyfish DNA I’ll also consider it falsified. It isn’t any harder to produce falsifiable predictions for theories built on a body of evidence. It’s usually much easier.

So the GQ and the spark for debate is: what evidence could I show you that would lead you to reject AGW? One again I’d like to stress that the question isn’t why falsifiable predictions can’t be made. The question is whether falsifiable predictions have been made. According to Popper it’s not science if the theory isn’t incompatible with certain possible results of observation. So what possible results of observation could I show you that would be incompatible with AGW?

I'm no scientist, but I would assume if you could show that the level of greenhouse gasses in the past had no effect on temperature that would falsify it. Right?

[GIGObuster]

Originally Posted by Blake

So I ask those of you who accept AGW and who believe it is good science: what evidence could I show you that would lead you to reject AGW? Obviously a prolonged period of cooling despite an ioncrase in atmospheric CO2 levels won’t do it. In the last 10 years global temperatures have been stable, and for the past five years the temperature trend has actually been negative fig 1. We’ve already had recent papers stating that temperature may not increase over the next decade, but nobody is predicting that they must decrease. IOW this isn’t itself a falsifiable prediction. In fact this makes me even more skeptical of AGW as a theory. It really does predict everything, since it can be used to predict prolonged periods of global cooling as well as periods of global warming.

We even had a discussion before on the stunt that "Lord" Monckton made regarding the link on "fig 1" (Yes, I was surprised that you want to pass that as good science.)

http://boards.straightdope.com/sdmb/...d.php?t=476074

It ain't good.

[Blake]

Originally Posted by Sage Rat

Any evidence for any theory which more accurately recreates the historical climate and conditions of things in modern times, would do.

Done.

The alternative theory is that it is all natural. And the evidence is “These results suggest that 20th Century warming trends are plausibly a continuation of past climate patterns. Results are not precise enough to solve the attribution problem by partitioning warming into natural versus human-induced components. However, anywhere from a major portion to all of the warming of the 20th Century could plausibly result from natural causes according to these results.”
Loehle, C. 2004; “Climate change: detection and attribution of trends from long-term geologic data.

And the IPCC itself says that pre-20th century events are plausibly natural and uninfluenced by humans.

So since you now have evidence of an alternative theory that that as accurately recreates the historical climate and conditions of things in modern times, do you reject Global Warming?
Of course you don’t.

Can I ask if you actually read the essay? Because your response is a classic example of what Popper said you can not do in science. It is easy to obtain confirmations, or verifications, for nearly every theory — if we look for confirmations. Confirmations count only if they are the result of risky predictions. The fact that AGW recreates historical climate and conditions of things in modern times doesn’t make it science. All you’ve done is gone and looked for confirmations that theory is true.

In fact your answer is non-responsive handwaving. What evidence could I show you that would constitute evidence for a theory which more accurately recreates the historical climate and conditions of things in modern times? It's turtles all the way down. What is the actual evidence that I could collect? Not vague references to evidence, but actual observations that I can go out and collect?

In short, what is the falsifiable prediction that you believe AGW makes? Surely it isn’t “It explains things at leats as well as the alternatives”?

That happens to be the standard for all theories.

No, it certainly is not. The standard, as already noted, is falsifiability. Freudian psychology and Astrology are not considered science because they are better than any alternatives.

The only challengers to the greenhouse gas based climate change theory that I've seen are that the sun is hotter/cyclical or that scientists/the UN is falsifying data.

The major challenger is the one that I out forward in the OP: that it is all natural and the precise drivers are too complex to understand.
There are any number of non-scientific theories that are more accurately explain events than a null hypothesis of “it’s natural”. No theory more accurately represents the origins of birds and their diversity in modern times than "God did it"? Evolutionary theory doesn’t come close to being as accurate as “God did it” because “God did it” represents everything perfectly 100% of the time. No matter what evidence you find “God did it” explains it 100%.

Does this mean that you accept “God did it” as a scientific? Of course you don’t. That’s because science isn’t based on accuracy. If you had bothered to read Popper’s essay you would know why. It’s because “God did it” and AGW are accurate because they can be used to explain everything. “I could not think of any behavior which could not be interpreted in terms of the theory. It was precisely this fact—that they always fitted, that they were always confirmed—which in the eyes of their admirers constituted the strongest argument in favor of these theories. It began to dawn on me that this apparent strength was in fact their weakness.” AGW suffers from the same weakness. To admirers like you this constitutes the strongest argument in favor of the theories. But it is the every antithesis of Popperian science.

So no, sorry “It explains everything better than the alternatives” does not constitute evidence that I can collect.
But please, if you can think of any actual evidence that I can collect then post it.

Originally Posted by Lobohan

I'm no scientist, but I would assume if you could show that the level of greenhouse gasses in the past had no effect on temperature that would falsify it. Right?

Possibly, but what is the observation you are proposing? What data can I go out and collect that will show you that the level of greenhouse gasses in the past had no effect on temperature? Everyone agrees that in the past temperatures rose and then CO2 levels increased. Would that evidence convince you that greenhouse gasses in the past had no effect on temperature? I can show you plenty of times in the past when CO2 level increased and temperature declined. Would that evidence convince you?

This is the question: what evidence can I collect that would lead you to reject AGW?

I can easily provide examples of evidence that you could collect that would cause me to reject evolution, or the germ theory of disease or megafauna overkill any other scientific theory that I accept. So what evidence could I collect that would cause you to reject AGW?

[Blake]

Originally Posted by GIGObuster

We even had a discussion before on the stunt that "Lord" Monckton made regarding the link on "fig 1" (Yes, I was surprised that you want to pass that as good science.)

Nothing in those links suggest the figure is inaccurate in any way.
So are you saying that the figure is inaccurate and that temperature in the past 6 years hasn't fallen. If not then what "stunt" of any relevance are you referring to? If so then how do you explain almost identical figures in this paper?

And would you care to address the actual subject of the debate: what evidence could show you that would cause you to reject AGW?

[GIGObuster]

I don't have much time, but recently one component of AGW, the Water Vapor Feedback was confirmed. What is important here is that many people against AGW told us that that was not happening.

The scientists at RealClimate have something to say regarding the overall falsifiability issue:

http://www.realclimate.org/index.php?p=258

Does "Global Warming Theory" pass Judge Jones' science test?

In one sense, the Theory of Global Warming is clearly a falsifiable scientific theory: all we need to do is wait around a while until industrial activities have doubled CO2, and observe what has happened to atmospheric temperature, water vapor and clouds. This indeed seems to be the experiment that most of the world seems intent on carrying out.

However, when we talk about "verifying" the Theory of Global Warming, what most of us have in mind is doing something to test the theory right now, so that (to the extent that it is correct) necessary policy decisions can be informed by the predictions of the theory.

Earth science shares the full range of difficulties generic to observational sciences, in that we can carry out laboratory experiments testing individual basic physical principles making up our theories, but have only limited opportunities to conduct experiments on the collective behavior of the whole system. For the latter, we must do the best we can with those ready-made examples that Nature provides. In this regard, the situation of the Theory of Global Warming is rather similar to that of the Theory of Evolution.

There are indeed a great many aspects of the Theory of Global Warming that are falsifiable without waiting for the next century's climate to come upon us. There are, to start, all the laboratory tests of basic physics, such as the infrared absorption properties of CO2 and water vapor. There are also field tests of the predictions of these basic physical theories, as is done when one measure water vapor and temperature in the atmosphere, and compares the predictions of radiative transfer theory with observed infrared radiation measured at the top of the atmosphere by satellite, or at the surface by radiation sensors. One can check the evaporation formulae used in climate models against the measured evaporation at buoys in the ocean, or the predictions of cloud models against observed cloud reflectivity. Going up the scale in complexity, one can compare the predictions of the theory against observations of recent climates, and of climates of the more distant past. General circulation models encapsulate the assumptions of the theory, and provide the tool necessary for testing hypotheses in such a complex system.

A further point regarding the positivist criterion is the the Theory of Global Warming is productive. The implied influence of CO2 (or methane) on climate can be, and has been, applied to the understanding of the Last Glacial Maximum, to Snowball Earth, to the Faint Young Sun, and to Cretaceous warmth. Variants apply also to Venus, Mars (present and past) and Titan. It is fair to say that this theory plays as central a role in the theory of planetary climate as the Theory of Evolution plays in biology. A relatied point is that the theory can be and has been challenged by data, and forced to adapt accordingly. This was the case in the precursor to the theory, when Tyndall discovered that minor constituents (CO2 and water vapor) dominated the greenhouse effect; the resulting adaptation of Fourier's theory opened the way for Arrhenius to conclude that human influences on the atmosphere could change the climate. A more recent adaptation was the incorporation of aerosol effects in the late 1980's which was forced upon the theory by the inability to explain the pattern of 20th century climate change with greenhouse gas increases alone. Contrary to the assertion in Mr. Williams' letter to the Chicago Tribune, revisions to the theory have not led to any systematic downward revision of the appraisal of the magnitude of the thread caused by doubling CO2. Indeed, some discoveries, notably the prevalance of abrupt climate change in the past record, have raised concerns that the current understanding may underpredict the magnitude of the response.

What of Judge Jones' other two criteria applied in the Kitzmiller case? The false duality issue does not arise in the judgement of Global Warming Theory itself, since the theory has never been argued for on the basis of such a stipulated duality ("The world is warming, and if it's not the Sun, then it must be CO2!"). On the other hand, a false duality has often been invoked in arguing against the Global Warming Theory. This typically takes the form of pointing out some aspect of the observations that Global Warming Theory doesn't explain, and then jumping to the conclusion that the observed warming must be due to the local skeptic's favorite cause: maybe solar variability, maybe some unspecified sort of "natural variability." Often such arguments involve holding Global Warming up to unreasonable standards of proof ("If we don't understand everything about climate, then we understand nothing about climate."), and often, like ID proponents arguing against Evolution, the arguments offered against Global Warming are at best distortions of scientific truth. In this regard, Global Warming plays the role of the Theory of Evolution, with the Global Warming Skeptics playing the role of ID advocates.

On Judge Jones' final criterion (presence in the peer-reviewed literature) the Theory of Global Warming gets an easy and obvious pass. Here, the Global Warming skeptics are in a somewhat better position than the ID advocates, in that a very few of the skeptics arguments have appeared in the peer reviewed literature. This doesn't make them right, but it does mean that to some extent, some of them are playing by the rules of science. Still, the relative paucity of skeptics arguments being played out in the peer reviewed literature suggests that they may not be as wrong as the ID advocates, but that they are not as right as the vastly greater number of researchers who have published in support of the Global Warming Theory.

[GIGObuster]

Originally Posted by Blake

Nothing in those links suggest the figure is inaccurate in any way.

The conclusions are still wrong. Even the Nature paper reports that:

Our results suggest that global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming.

IMHO I do remember that the temperature graphs that include the recent century show periods of almost 20 years were there was very little change, the problem is that AGW makes the temperature jump up after those periods of stability.

BTW there are issues with that "Energy and Environment" publication:

http://www.realclimate.org/index.php?p=111

http://www.realclimate.org/index.php?p=109#ee

[Shalmanese]

I disagree with your premise. Popper's definition is a workable one for experimental sciences but discounts all observational sciences which include commonly accepted scientific disciplines such as cosmology, geography, astrophysics and paleontology. Going by the strict standard posited in your OP, none of these would be counted as science.

If I argue that "frog extinction in the lower San Juan Valley was caused by an increase in pollutants caused by plastic manufacturers", this is strictly not a falsifiable statement because I have no other San Juan Valleys, no other frog ecosystems and no other universes without plastic manufacturers. I can build up models and make inferences from smaller scale experiments but it's never going to be possible for me to generate a falsifiable experiment unless I can build replica universes.

Observational sciences lean heavily on modeling and statistics and come from a different philosophical tradition from experimental sciences. Given that you work as an ecologist, I'm puzzled as to why you believe falsifiability is a good criteria for AGW when it's clearly not the working definition of observational science.

[Half Man Half Wit]

Well, if we continue to produce climate gases and temperatures fail to rise, global warming will be falsified. Conversely, if we significantly reduce emissions, yet temperatures rise unabatedly over a period long enough to exclude possible lag/inertia issues, anthropogenic global warming will be falsified. Unfortunately, we don't have the means necessary to set up a rigorous control experiment (and if we had, the issue would be pretty much void, anyway), and models can only go so far, but the in principle falsifiability is there.

Conversely, the hypothesis that it's some unknown natural process is unfalsifiable pretty much by definition.

[Dead Badger]

Originally Posted by Shalmanese

I disagree with your premise. Popper's definition is a workable one for experimental sciences but discounts all observational sciences which include commonly accepted scientific disciplines such as cosmology, geography, astrophysics and paleontology. Going by the strict standard posited in your OP, none of these would be counted as science.

Quite. The OP indulges in a spot of equivocation between logical falsifiability and practical falsifiability. Any half-decent AGW statement should be logically falsifiable; the problem is that obtaining the data that would falsify it is near impossible, simply because we've only got one Earth, and we're all sat on it, screwing with the data. Assuming, perhaps unfairly, that the OP would like at some stage to exclaim, "aha! Your theories are unfalsifiable, and should therefore be discounted," it should be noted that the argument applies to every theory of climate change, be it anthropogenic, solar cyclic or intergalactic nazi lizard-based. Assuming we're not going to throw up our hands and give up all hope of ever understanding our global climate, this standard isn't a helpful one in determining a theory's worth.

Should any passing deity be kind enough to provide us with a control Earth, of course, then things will be different.

[Blake]

Originally Posted by Shalmanese

I disagree with your premise. Popper's definition is a workable one for experimental sciences but discounts all observational sciences which include commonly accepted scientific disciplines such as cosmology, geography, astrophysics and paleontology. Going by the strict standard posited in your OP, none of these would be counted as science.

Did you miss where I said that i didn;t want to debate Popperian science?

And did you miss where I said that I am an observational scientist: an ecologist.

And did you miss where Popper used an example from astrophysics (gravitational lensing) to defend GR as being good science

Let me assure you that Popperian science works perfectly in ecology, geography and astrophysics at least.

But that's OK. You've admitted that AGW isn't falisfiable by definition. Next thread we can debate whether it's science at all.

[Blake]

Originally Posted by GIGObuster

I don't have much time, but recently one component of AGW, the Water Vapor Feedback was confirmed.

And I repeat Popper: it is easy to obtain confirmations, or verifications, for nearly every theory — if we look for confirmations. This apparent strength was in fact their weakness

Originally Posted by GIGObuster

The conclusions are still wrong. Even the Nature paper reports that:

But I never referenced the conclusions. I referenced a single, accurate figure.

So can you please stop hijacking my thread.

[Blake]

Originally Posted by Half Man Half Wit

Well, if we continue to produce climate gases and temperatures fail to rise, global warming will be falsified.

So would you consider that the decline in temperature in the middle of the last century to falsification? Temperatures declined despite increased production of "climate gases"?

Conversely, if we significantly reduce emissions, yet temperatures rise unabatedly over a period long enough to exclude possible lag/inertia issues, anthropogenic global warming will be falsified. Unfortunately, we don't have the means necessary to set up a rigorous control experiment (and if we had, the issue would be pretty much void, anyway), and models can only go so far, but the in principle falsifiability is there.

Thank you. The first actual evidence. But as you point out, we don't actually have any method of collecting such evidence.

Conversely, the hypothesis that it's some unknown natural process is unfalsifiable pretty much by definition.

Of course it is. It's actually an admission of ignorance. which has always been a sound scientific defence. A scientist isn't obliged to accept the existence of gods just because she can't come up with a better theory to explain a phenomenon. She can say that gods themselves are untestable and hence unscientific and ascribe it to natural effects.

It would be a strange world if we had to accept something as science simply because we couldn't come up with a better explanation. No?

[Blake]

Originally Posted by Dead Badger

Quite. The OP indulges in a spot of equivocation between logical falsifiability and practical falsifiability. Any half-decent AGW statement should be logically falsifiable; the problem is that obtaining the data that would falsify it is near impossible, simply because we've only got one Earth, and we're all sat on it, screwing with the data.

Fine, you admit that AGW doesn't meet the standard Popperian definition of science. Not only that, but it can not meet it.

Assuming, perhaps unfairly, that the OP would like at some stage to exclaim, "aha! Your theories are unfalsifiable, and should therefore be discounted," it should be noted that the argument applies to every theory of climate change, be it anthropogenic, solar cyclic or intergalactic nazi lizard-based.

Assuming that you are right (which I don't think I do) then using Poppers standard this just means that any study of climate change is not a science.

Assuming we're not going to throw up our hands and give up all hope of ever understanding our global climate, this standard isn't a helpful one in determining a theory's worth.

Why isn't it helpful? Why can't I evaluate a theory as scientifically worthless if it fails to meet the criteria of scientific worth? This seems like a total non sequitur. How else should one evaluate a theory's scientific worth beyond gauging it against criteria of scientific worth?

If I told you that I was studying the geology of Pluto using a crystal ball, would you accept my study as scientific simply because we have no way to scientifically study the geology of Venus? Or would yo declare it to be unscientific because it doesn't meet your criteria of scientific worth.

Your statement here seem like a non sequitur, but please feel free to expand on your reasoning. I would genuinely like to know how the fact that a scientific study of climate change is technolgically impossible makes it harder to determine a theory's scientific worth. I would have thought it made it easier.

[Quartz]

I have yet to see one decent test of the falsifiability of AGW. Part of the problem is that we really don't sufficiently understand what's going on. Perhaps a bigger part of the problem is the terrible treatment of those who depart from the consensus. Bjorn Lomborg is the classic case, though ironically, he thinks AGW is true, just disagrees on what we should do about it.

[Walker in Eternity]

Originally Posted by GIGObuster

We even had a discussion before on the stunt that "Lord" Monckton made regarding the link on "fig 1" (Yes, I was surprised that you want to pass that as good science.)

http://boards.straightdope.com/sdmb/...d.php?t=476074

It ain't good.

Why put the Lord in quotes? He's a Viscount and as far as I can tell his title is legitimate.

[Walker in Eternity]

Originally Posted by Shalmanese

I disagree with your premise. Popper's definition is a workable one for experimental sciences but discounts all observational sciences which include commonly accepted scientific disciplines such as cosmology, geography, astrophysics and paleontology. Going by the strict standard posited in your OP, none of these would be counted as science.

I disagree on two of your examples, both cosmology and astrophysics make theorectical predictions that can potentially be falsified by either observation or experiment e.g. cosmic background radiation (WMAP), gravitational wave amplitude from the early universe (LISA).

I suspect that a geologist and/or paleontologist will be along shortly to refute the other two as well.

[Half Man Half Wit]

Originally Posted by Blake

So would you consider that the decline in temperature in the middle of the last century to falsification? Temperatures declined despite increased production of "climate gases"?

I'm not equipped to make that judgement; however, I can promise you, in 50 years from now, if we've continued to blow out greenhouse gasses and the temperatures have stayed at the level they are now, I'll happily grant that AGW has been falsified -- and I do mean 'happily', because me being wrong about this appears to be by far the most favourable alternative when compared to the potential disasters that are thought to come bundled with a global rise in temperature.

Thank you. The first actual evidence. But as you point out, we don't actually have any method of collecting such evidence.

Well, we could try to reduce emissions, and see if temperatures rise anyway...

Of course it is. It's actually an admission of ignorance. which has always been a sound scientific defence. A scientist isn't obliged to accept the existence of gods just because she can't come up with a better theory to explain a phenomenon. She can say that gods themselves are untestable and hence unscientific and ascribe it to natural effects.

But AGW isn't untestable like gods are: again, if there is no rise in temperature, there is no global warming, and hence, no anthropogenic global warming. And even the existence of gods (or the supernatural in general) would have to be taken into consideration if it turns out to be impossible to find another explanation.

It would be a strange world if we had to accept something as science simply because we couldn't come up with a better explanation. No?

But what you actually are proposing is to accept having no explanation in favour of an explanation you don't like; if that's a way to do science, it's a way that's new to me. Any possible explanation (gods aren't, as far as science is concerned, a possible explanation; AGW certainly is) is automatically favoured over none at all; only if that explanation has been ruled out can one revert to a state of ignorance.

The thing about AGW is that it's such an eminently reasonable assumption to make: CO₂ does have the simple physical property of being what's called a 'greenhouse gas', i.e. it is able to absorb and emit radiation in the thermal infrared range, and we have elevated its concentration in the atmosphere; that this leads to warming is the natural conclusion to draw, and what looked like warming was the reason to look for such a mechanism in the first place. Of course, there may be some as yet unknown (to me, at least) 'heat dumping'-mechanism, but to posit such in the absence of evidence for it would be highly unscientific. (That, by the way, in the past carbon dioxide emissions lagged behind temperature rises is a consequence of there not being a natural mechanism to throw the CO₂ emission/immission equilibrium out of balance -- dinosaurs had preciously little industry, in other words.)

[Half Man Half Wit]

Originally Posted by Blake

Fine, you admit that AGW doesn't meet the standard Popperian definition of science. Not only that, but it can not meet it.

Perhaps a bit of a hijack, but what would that actually change? If we now ruled that, yes, AGW is fundamentally unfalsifiable and hence to be expelled from the realms of good science, that doesn't rule out the possibility that our continued emission of greenhouse gases leads to catastrophic warming in the slightest; we just wouldn't be allowed to call it 'science' any more when we're discussing this possibility. It would merely be a difference of label, not one of content, and otherwise the discussion would have to go on pretty much the same way it does now: we should hope that AGW is false, while worrying about (and planning for) the possibility that it is true.

[Blake]

Originally Posted by Walker in Eternity

I suspect that a geologist and/or paleontologist will be along shortly to refute the other two as well.

I'm not a geologist an I can point out that plate tectonics is falsifiable.

I have no idea where this odd notion came from that observational sciences don't operate on falsifiability. I've worked in an observational science for many years and I've never operated on anything but falsifiability. just because I can't see what plants an animals lived in an area before human disturbance that doesn't mean I can't falsify any hypotheses. I can make a prediction of what the pollen record of nearby sediments should show, or look at isotopes in the soil, or make a prediction about what I should find at undisturbed sites elsewhere. If any of those observations fail to match my predictions the hypothesis is falsified.

And for the life of me I can't see why palaeontology couldn't make very similar predictions. The idea that palaeontology can't produce falsifiable predictions seems incredible.

[Quartz]

Originally Posted by Half Man Half Wit

But AGW isn't untestable ... if there is no rise in temperature, there is no global warming, and hence, no anthropogenic global warming.

This is not correct: there may be cooling going on and mankind may be countering it, producing a nil net effect.

Your statement shows how complex the matter is.

[Blake]

Originally Posted by Half Man Half Wit

Well, we could try to reduce emissions, and see if temperatures rise anyway...

Or we could continue to increase emissions and see if it fails to rise, as you said earlier.

But AGW isn't untestable like gods are: again, if there is no rise in temperature, there is no global warming, and hence, no anthropogenic global warming.

I'm afraid I don't understand this. Are you saying that the only warming the Earth ever experiences is anthropogenic?

And even the existence of gods (or the supernatural in general) would have to be taken into consideration if it turns out to be impossible to find another explanation.

No, it certainly wouldn't. There are a great many things that science can't explain. We don't incorporate a God of gaps.

But what you actually are proposing is to accept having no explanation in favour of an explanation you don't like

It has nothing to do with what I like. it has to do with whether it is science. If you want to invoke a religious explanation or any other explanation that's fine with me. It still doesn't make it science.

gods aren't, as far as science is concerned, a possible explanation

This is a total non sequitur.
Science is something that is falsifiable. If AGW isn't falsifiable then why is it any more science than gods?

Any possible explanation (is automatically favoured over none at all; only if that explanation has been ruled out can one revert to a state of ignorance.

Cite. Seriously, where is that in the Popperian definition of science?

Any falsifiable explanation is science. If the explanation isn't falsifiable it is ruled out as being science. Where does it say that you can accept unfalsifiable explanations as science so long as you have no replacement theory?

The thing about AGW is that it's such an eminently reasonable assumption to make

Yes, just like the eminently reasonable assumption that the Earth is flat and that the sun orbits it. Or the eminently reasonable assumption that black people are less technologically advanced because they are closer to apes.

In the entire history of the world has any eminently reasonable assumption actually been correct? I can't think of any, but even if there have been a few the fact that so many have been proven false shows why science relies on falsifiablity, not eminent reaosnablenesss.

[Stanislaus]

Originally Posted by Popper

At the same time I realized that such myths may be developed, and become testable; that historically speaking all — or very nearly all — scientific theories originate from myths, and that a myth may contain important anticipations of scientific theories. Examples are Empedocles' theory of evolution by trial and error, or Parmenides' myth of the unchanging block universe in which nothing ever happens and which, if we add another dimension, becomes Einstein's block universe (in which, too, nothing ever happens, since everything is, four-dimensionally speaking, determined and laid down from the beginning). I thus felt that if a theory is found to be non-scientific, or "metaphysical" (as we might say), it is not thereby found to be unimportant, or insignificant, or "meaningless," or "nonsensical."[4] But it cannot claim to be backed by empirical evidence in the scientific sense — although it may easily be, in some genetic sense, the "result of observation."

When Popper speaks of ideas becoming testable, it suggests that the same hypothesis may move from "non-scientific" to "scientific" as our ability to falsify it develops. For example, Democritus proposed that all matter was created of indivisible particles, which he called atoms. My question is, was this a scientific theory? Or did it only become one thousands of years later, when we gained the ability to observe matter on the atomic scale?

If AGW could only be falsifed by conducting some impossibly elaborate experiment or simulation which it was utterly beyond our current technical ability to actually do, would that make it non-scientific? There's surely a difference between being non-falsifiable (i.e. not falsifiable under any circumstances) and unfalsifiable (i.e. not able to be falsified by any means at our disposal right now.)

Also, Popper's quote above would suggest that, should we conclude AGW was non-scientific, it could still very well be important, significant, meaningful and sensible. In which case, the right response may very well be to continue researching the climate with a view to a)refining the AGW hypothesis and/or b)improving our ability to falsify it.

[Quartz]

Originally Posted by Half Man Half Wit

But what you actually are proposing is to accept having no explanation in favour of an explanation you don't like; if that's a way to do science, it's a way that's new to me.

Remind me of your scientific credentials. Liking or not liking an explanation doesn't come into it. There's plenty of stuff for which we have no explanation. Sure we can invent hypotheses to explain them, but we don't accept even the most plausible until they're proven. In the interim, we accept that there is currently no explanation.

The thing about AGW is that it's such an eminently reasonable assumption to make

The thing about AGW is that being a reasonable assumption does not make it correct. Newton's Laws of Motion were reasonable - and were a tremendous achievement - and passed everyday tests; Einstein had to correct them.

[Blake]

Originally Posted by amrussell

For example, Democritus proposed that all matter was created of indivisible particles, which he called atoms. My question is, was this a scientific theory? Or did it only become one thousands of years later, when we gained the ability to observe matter on the atomic scale?

It was unscientific. A completely different theory with the same prediction was scientific at a later date. I can't see how the fact that the two theories have the same prediction means they both have to be scientific.

Genesis and evolution both predicted that humans would appear in the fossil record after all other species. Does that make genesis scientific?

If AGW could only be falsifed by conducting some impossibly elaborate experiment or simulation which it was utterly beyond our current technical ability to actually do, would that make it non-scientific?

What if we replace AGW in that sentence with "Astrology" or "Freudian Psychology" or "Christianity" or any other psuedosciene? Because the statement is no less true and no less nonsensical for such a change.

There's surely a difference between being non-falsifiable (i.e. not falsifiable under any circumstances) and unfalsifiable (i.e. not able to be falsified by any means at our disposal right now.)

If there is such a difference then we will have to concede Astrology or Freudian Psychology and Christianity are also unfalsifiable. And if we accept that, then precisely what utility do you see in distinguishing between unfalsifiable and non-falsifiable?

Also, Popper's quote above would suggest that, should we conclude AGW was non-scientific, it could still very well be important, significant, meaningful and sensible. In which case, the right response may very well be to continue researching the climate with a view to a)refining the AGW hypothesis and/or b)improving our ability to falsify it.

True enough. However what it doesn't suggest is that we must or even should do so. Most unfalsifiable theories are invalid and useless. Some, as Popper notes, are not. So while we shouldn't discount all theories because they are unscientific that doesn't mean that we have to accept them all either. They laughed at Newton and they laughed at Columbus but they also laughed at Bozo the Clown.

[Stanislaus]

Originally Posted by Blake

It was unscientific. A completely different theory with the same prediction was scientific at a later date. I can't see how the fact that the two theories have the same prediction means they both have to be scientific.

Genesis and evolution both predicted that humans would appear in the fossil record after all other species. Does that make genesis scientific?

I'd query, given that Genesis flatly contradicts the possibiliity of a fossil record, whether it predicts any such thing. But we've been given the criterion for "scientific-ness" - making falsifiable predictions. If you assure me that Genesis does make such a prediction, then I will agree that it is scientific. I wouldn't want to be accused of picking and choosing what is science based on my own irrational prejudices.

What if we replace AGW in that sentence with "Astrology" or "Freudian Psychology" or "Christianity" or any other psuedosciene? Because the statement is no less true and no less nonsensical for such a change.

Again, I'd query the idea that Astrology doesn't make predictions - I'd have said that it made pretty obvious predictions which were easily disproven. But that's beside the point - Christianity, to pick another example, doesn't make any predictions that could theoretically be proven with suitably advanced techonology - it's metaphysical in essence. Similarly, I'm unaware of any claims that Freudian Psychology could be proven if only we had sufficiently advanced brain scanning equipment.

By contrast, it seems to me - and I'm open to correction - that AGW could in theory be falsified: that with hugely powerful computers, a rigorous understanding of all the factors that influence climate and super-sensitive measuring equipment, it could be shown that the release of GHGs by humans had the effect of warming the planet over and above what it would be under "natural" conditions, or not. Does the fact that we cannot do this now mean that AGW is in the same class as Christianity as a theory?

In fact, here's a thought experiment. Say that, in the year 2154, mankind will have developed the technology and understanding to falsify the current AGW theory by means of experiment. In what year does AGW become science?

If there is such a difference then we will have to concede Astrology or Freudian Psychology and Christianity are also unfalsifiable. And if we accept that, then precisely what utility do you see in distinguishing between unfalsifiable and non-falsifiable?

I disagree entirely. As above, I would say that Christianity is non-falsifiable in essence - there is no even theoretical experiment that would prove or disprove Christ's claim to be the Way, the Truth and the Life. Whereas, for example, if I went back in time to, say, 1689 and presented Huygens with the theoretical basis for GR, that would merely be unfalsifiable - Huygens would be unable to make sufficiently accurate measurements to test the theory, owing solely to the paucity of his equipment. Does that make the difference clearer?

True enough. However what it doesn't suggest is that we must or even should do so. Most unfalsifiable theories are invalid and useless. Some, as Popper notes, are not. So while we shouldn't discount all theories because they are unscientific that doesn't mean that we have to accept them all either. They laughed at Newton and they laughed at Columbus but they also laughed at Bozo the Clown.

Hmm. Saying, "Other unfalsifiable theories were useless, therefore this one is useless" strikes me as a somewhat fallacious decision-making process.

[GIGObuster]

Originally Posted by Blake

And I repeat Popper: it is easy to obtain confirmations, or verifications, for nearly every theory — if we look for confirmations. This apparent strength was in fact their weakness

That really sounds like grasping at straws.

The fact is that the water vapor feedback was pointed as important for the Greenhouse gas theory to work, deniers on the Straight Dope even told us that the water vapor feedback was not demonstrated as it was mostly coming from the physical computer models.

Had the new tests and satellite data (yes, a satellite was launched also to get data to confirm the results of the mostly theoretical experiments until then) had demonstrated that the water vapor feedback with CO2 was hooey then a huge component of the prediction models and the theory behind AGW would have gone up in smoke.

http://www.sciencedaily.com/releases...0219152132.htm

But I never referenced the conclusions. I referenced a single, accurate figure.

So can you please stop hijacking my thread.

It is still bad science.

Starting his graph from 2001 or 2002 does not make much a difference in the fact that he is being misleading.

http://www.realclimate.org/index.php...-manipulation/

Our favorite contrarian, the potty peer Christopher Monckton has been indulging in a little aristocratic artifice again. Not one to be constrained by mere facts or observable reality, he has launched a sally against Andy Revkin for reporting the shocking news that past industry disinformation campaigns were not sincere explorations of the true uncertainties in climate science.

The letter he has written to the NY Times public editor, with its liberal sprinkling of his usual pomposity, has at its heart the following graph:

Among other issues, it is quite amusing that Monckton apparently thinks that;

* trends from January 2002 are relevant to a complaint about a story discussing a 1995 report,
* someone might be fooled by the cherry-picked January 2002 start date,
* no-one would notice that he has just made up the IPCC projection curves

The last is even more amusing because he was caught out making stuff up on a slightly different figure just a few weeks ago.

To see the extent of this chicanery, one needs only plot the actual IPCC projections against the observations. This can be done a number of ways, firstly, plotting the observational data and the models used by IPCC with a common baseline of 1980-1999 temperatures (as done in the 2007 report) (Note that the model output is for the annual mean, monthly variance would be larger):

These show clearly that 2002-2009 is way too short a period for the trends to be meaningful and that Monckton's estimate of what the IPCC projects for the current period is woefully wrong. Not just wrong, fake.

[GIGObuster]

Originally Posted by Walker in Eternity

Why put the Lord in quotes? He's a Viscount and as far as I can tell his title is legitimate.

It seems to me that that is doubtful, like his work.
http://scienceblogs.com/deltoid/2009...ing_things.php

With his latest shenanigans in the US, Monkton managed to catch the attention of Private Eye (a satirical current affairs magazine in the UK).

In the latest issue 1235, they noted several things (quite apart from his dodgy science).

One is his reference to himself as "a member of the Upper House of the United Kingdom legislature" in a letter to two American senators. He is not of course and never has been. As Private Eye notes: "Since inheriting the title, Christopher has stood at a "by-election" for a hereditary Tory seat in the Lords, following the death of Lord Mowbray and Stourton two years ago. He received precisely zero votes."

The other thing Private Eye notes is his logo, which he is using on his graphs and letters - a portcullis topped with a crown, bearing a striking resemblance to the insignia of the House of Parliament. This is also very dodgy indeed as the official parliamentary guide states very clearly that "the usage of the crowned portcullis was formally authorised by Her Majesty the Queen for the two Houses unambiguously to use the device and thus to regulate its use by the others. The emblem should not be used for purposes to which such authentication is inappropriate, or where there is a risk that its use might wrongly be regarded, or represented as having the authority of the House".

[Shalmanese]

Originally Posted by Blake

Did you miss where I said that i didn;t want to debate Popperian science?

Nope.

And did you miss where I said that I am an observational scientist: an ecologist.

Nope, did you miss the part of my post where I pointed out you were an ecologist and so was therefore puzzled as to the way you set up your definitions?

And did you miss where Popper used an example from astrophysics (gravitational lensing) to defend GR as being good science

Yup, could you point me to it? I did a google search for "Karl Popper" "gravitational lensing" and I'm not coming up with anything interesting. I'd be interested to read this but I have a rough ideal of what it would say.

Let me assure you that Popperian science works perfectly in ecology, geography and astrophysics at least.

I'd like you to expand about this. There are different kinds of observational sciences and Popper's definition works to some extent for some of them.

Some observational sciences generate so much data that scientists can afford to just patiently wait until the universe provides an experiment which they would have run anyway. In which case, Popperian criterion works much as they would for an experimental science.

Some observational sciences generate a steady stream of data but there are systematic biases that can never be accounted for. AGW is one of these because we only have one earth to experiment, in which case, Popper is useful for the aspects of the theory that don't depend on unique features of the earth.

Some observational sciences work from a fixed set of data that can never be expanded upon in which case Popper's criterion is wholly useless.

But that's OK. You've admitted that AGW isn't falisfiable by definition. Next thread we can debate whether it's science at all.

Yes, I've admitted that AGW falls into the set of non-falsifiable theories that includes astrology, astronomy, paleontology, cryptozoology, geography, exobiology & religion. Now the question is, how is this a useful set? The reason I dispute your premise is because I think you've set it up to generate an ultimately uninteresting answer.

[Half Man Half Wit]

Originally Posted by Quartz

This is not correct: there may be cooling going on and mankind may be countering it, producing a nil net effect.

Just how likely do you think that the random amount of warming we have introduced happens to exactly counterbalance the random amount of cooling that occurs naturally by an as yet unknown process for which there exists zero evidence? And how scientific do you think this hypothesis is?

Originally Posted by Blake

Or we could continue to increase emissions and see if it fails to rise, as you said earlier.

Yes, both possible avenues for falsification. However, it's not just dispassionate science we're doing here, unfortunately, if worst comes to worst, there may be human lives at stake.

I'm afraid I don't understand this. Are you saying that the only warming the Earth ever experiences is anthropogenic?

Actually, I said that if there's no warming at all, there can surely be no anthropogenic warming. Sorry if that wasn't clear.

No, it certainly wouldn't. There are a great many things that science can't explain. We don't incorporate a God of gaps.

Great! I wasn't arguing for a god of the gaps (and I hate the argument with a passion). However, if all natural explanations have been excluded (however epistemologically difficult or impossible that may be), then supernatural ones are all that remain.

It has nothing to do with what I like. it has to do with whether it is science. If you want to invoke a religious explanation or any other explanation that's fine with me. It still doesn't make it science.

Then why that need to equate AGW with religion in such a straw man way? If you were truly arguing from a scientific viewpoint an in the interest of such a viewpoint, you could assess the hypothesis on its merits and reach a conclusion without much fuss; heck, you could even conclude that climate studies are not an area worthy of your scientific attention and do whatever the heck else you want.

This is a total non sequitur.
Science is something that is falsifiable. If AGW isn't falsifiable then why is it any more science than gods?

You're mixing two things up here: first, I do consider AGW to be falsifiable, and you seemed to agree with the falsification scenarios I drew up. Second, as I said in this post, the question is ultimately a purely academic one anyway -- what matters is whether it's real or not, and whether you (or I or whoever else) choose to call it science or not does not impinge on that question in the slightest. Indeed, I'd be happy to renounce the scientific nature of AGW once and for all and have everybody shot who so much as dares to use the two words in one sentence if that meant we could just sit down and work out whether or not there's a danger, how big it is, and what the best course of action is going to be; the moniker is wholly irrelevant to me.

Cite. Seriously, where is that in the Popperian definition of science?

It's not in Popper's essay because that was not what he concerned himself with in it; he merely establishes falsification as a necessary criterion for calling a theory scientific, however, I doubt he would have claimed that in doing so he had exhaustively circumscribed the whole area of scientific inquiry. However, I'm curious as to what it is you would have me cite -- that in order to do science, one needs to consider the hypotheses formulated to explain the empirical data before dismissing them? Honestly?

Any falsifiable explanation is science. If the explanation isn't falsifiable it is ruled out as being science. Where does it say that you can accept unfalsifiable explanations as science so long as you have no replacement theory?

Well, I don't hold AGW to be unfalsifiable, since it does make clear predictions about the future -- indeed, it is nothing but a prediction about the future! (And can an explanation even be truly an explanation if it's not falsifiable? Seems to me that 'god did it'-like statements never actually explain anything so much as accept the unknowable nature of the true explanation; but that's largely beside the point.)

Yes, just like the eminently reasonable assumption that the Earth is flat and that the sun orbits it. Or the eminently reasonable assumption that black people are less technologically advanced because they are closer to apes.

All of which was eventually supplanted by better models, none of which was 'something unknown is doing we don't know what'. I am happy to follow a climate model in better accord with the data up to this point, or in some other way preferable. Discarding the by a wide margin only reasonable model we have in favour of ignorance because of some philosophical quibble regarding the proper definition of the word 'science' runs counter to any sensible understanding of it.

Originally Posted by Quartz

Remind me of your scientific credentials.

Please. Weighing our respective degrees against each other isn't going to settle the argument one way or the other. (And if that were the case, AGW would nowadays be considered an established fact.)

Liking or not liking an explanation doesn't come into it. There's plenty of stuff for which we have no explanation. Sure we can invent hypotheses to explain them, but we don't accept even the most plausible until they're proven. In the interim, we accept that there is currently no explanation.

Funny how you call my credentials into question and then go on to talk about proving things in science. What has ever been proven in science? There are always only candidate explanations with varying levels of evidence speaking for them; as things are, our candidate explanations regarding the development of the climate are 1) AGW and 2) I dunno, them things just happen.

[Left Hand of Dorkness]

I'm a total layman, so I can't possibly contribute productively to these debates. I do have a question, though. Blake, what evidence would falsify the hypothesis that global warming is not caused by humans?

[Half Man Half Wit]

Or consider this analogy:

An asteroid is headed to intersect Earth's orbit. Due to some quirk in its orbit, or maybe the insufficient nature of our means (picture tech some 50 years ago), it is impossible to predict with absolute certainty whether we'll get it, or it'll be a near miss; some say it'll hit, some say it won't. With a concerted global effort, we could probably avert a possible collision, or perhaps not. This is analogous to the situation with AGW: maybe it's coming, maybe it ain't; maybe we can do something about it, maybe we can't, and in both cases, it's impossible to know for sure until 'after the fact'.

Would you now judge the hypothesis that the asteroid might hit us 'unscientific'? And would your recommended course (whichever it might be) of action depend in any way on this judgement?

[DrDeth]

Although I have little doubt that humans are having an effect on the climate, the Medieval Warm Period occurred with no significant human input.

GIGObuster: there is absolutely no doubt that Christopher Walter Monckton, is indeed 3rd Viscount Monckton of Brenchley. NONE. He is not a member of the current House of Lords, true but that doesn't mean he is not a Viscount and thus Lord Monckton.

[GIGObuster]

Originally Posted by DrDeth

Although I have little doubt that humans are having an effect on the climate, the Medieval Warm Period occurred with no significant human input.

GIGObuster: there is absolutely no doubt that Christopher Walter Monckton, is indeed 3rd Viscount Monckton of Brenchley. NONE. He is not a member of the current House of Lords, true but that doesn't mean he is not a Viscount and thus Lord Monckton.

Monckton clearly is trying to pass himself as a member of the house of lords, when his lordship is only because of who his relatives were that does diminish any authority that he claims.

But more importantly his latest claims were made by making underhanded moves to convince others that he was being respected in academia, he is not.

[DrDeth]

Originally Posted by GIGObuster

Monckton clearly is trying to pass himself as a member of the house of lords, when his lordship is only because of who his relatives were that does diminish any authority that he claims.

t.

No, he protesting how the new House of Lords is selected. In any case, member of the House of Lords or not, he's still Lord Monckton.

[GIGObuster]

Originally Posted by DrDeth

Although I have little doubt that humans are having an effect on the climate, the Medieval Warm Period occurred with no significant human input.

http://www.newscientist.com/article/...n-england.html

Climate myths: It was warmer during the Medieval period, with vineyards in England

...

In the southern hemisphere, the picture is even more mixed, with evidence of both warm and cool periods around this time. The Medieval Warm Period may have been mostly a regional phenomenon, with the extremes reflecting a redistribution of heat around the planet rather than a big overall rise in the average global temperature.

What is clear, both from the temperature reconstructions and from independent evidence - such as the extent of the recent melting of mountain glaciers - is that the planet has been warmer in the past few decades than at any time during the medieval period. In fact, the world may not have been so warm for 6000 or even 125,000 years (see Climate myths: It has been warmer in the past, what's the big deal?).

What really matters, though, is not how warm it is now, but how warm it is going to get in the future. Even the temperature reconstructions that show the greatest variations in the past 1000 years suggest up until the 1980s, average temperature changes remained within a narrow band spanning 1ºC at most. Now we are climbing out of that band, and the latest IPCC report (pdf format) predicts a further rise of 0.5ºC by 2030 and a whopping 6.4ºC by 2100 in the worst case scenario.

[GIGObuster]

Originally Posted by DrDeth

No, he protesting how the new House of Lords is selected. In any case, member of the House of Lords or not, he's still Lord Monckton.

Lord in the family sense, and nothing else, regardless of what he pretends to be. I would not have a beef if it wasn't for the fact that he is making an effort to pass himself as a member of the house.

[Shalmanese]

Originally Posted by Blake

I'm not a geologist an I can point out that plate tectonics is falsifiable.

I have no idea where this odd notion came from that observational sciences don't operate on falsifiability. I've worked in an observational science for many years and I've never operated on anything but falsifiability. just because I can't see what plants an animals lived in an area before human disturbance that doesn't mean I can't falsify any hypotheses. I can make a prediction of what the pollen record of nearby sediments should show, or look at isotopes in the soil, or make a prediction about what I should find at undisturbed sites elsewhere. If any of those observations fail to match my predictions the hypothesis is falsified.

And for the life of me I can't see why palaeontology couldn't make very similar predictions. The idea that palaeontology can't produce falsifiable predictions seems incredible.

My claim is not that all observational science is unfalsifiable but that there exists claims in observational science which are unfalsifiable.

Consider Jared Diamond's reporting of Barry Rolett's claim in page 115-118 of Collapse. Rolett looked at the degree of deforestation on 81 polynesian islands and came up with a model for deforestation that involved 9 different variables.

Is his hypothesis true? Who knows? Is it scientific? I would argue that it is. Is it falsifiable? Hell no.

How would you falsify a claim like that? It's not like you can generate an 82nd island to test the model. The entire sum of the dataset for all eternity is going to be 81 islands. Given that there's an infinite number of models that would explain such data, how can we be sure Rolett's 9 factor one is the correct one?

[Public Animal No. 9]

The key question that would have to be shown to be falsifiable, IMHO, is what is cause and what is effect. We can easily demonstrate whether or not increases in greenhouse gases change the radiative properties of air to retain more radiative energy. We can demonstrate whether emissions of those gases are anthropogenic. We can demonstrate the effects of water vapor or clouds.

What the key issue is, then, is whether the increases in greenhouse gases cause warming or whether warming causes increases in greenhouse gases. It may be my ignorance of the science of natural processes, but the latter cause-effect relationship seems to me to be the more difficult one to demonstrate. For the former, we can (and have) estimated the amount of GHGs generated through (primarily) combustion of fossil fuels, and from other anthropogenic sources, and we have a pretty good handle on how those gases influence the radiative properties of air. This was done well over 100 years ago by Arrhenius, who was the first to suggest that the climate could be altered by fossil fuel use.

The ease of demonstrating a hypothesis (at least theoretically) does not lead to a conclusive answer, given the real-world complexities. Nor does the difficulty of demonstrating a competing hypothesis disprove that theory. But for me, the first step in falsifying AGW is to demonstrate that the increased anthropogenic emissions of greenhouse gases does not result in changes to the atmosphere's radiative balance.

Most of what I've seen about this from the skeptics leans on complex natural processes to counteract any warming effect - to my mind, they seem to agree that increased GHG concentrations would result in a warming tendency, since I have not seen anything that contradicts that basic relationship (such a contradiction may be out there, I just haven't seen it).

But much more often, the arguments tend to be about which is cause and which is effect. I tend to side with those that say we will have to wait to find out conclusively. There may be ways to demonstrate which it is, but in the meantime, the first steps we would take to reduce emissions have other major benefits, such as more efficient use of energy and reducing our reliance on unstable energy sources (oil).

By the time we're ready to really implement any major carbon reduction approaches, like capturing and storing CO2, our understanding of the atmospheric dynamics will have improved, perhaps to the point where it's exceedingly clear what the causes and effects are. It would be nice to be able to say that we would have "undeniable" evidence, but there will always be those who will deny anything that leads to a conclusion they don't like.

[Sage Rat]

Originally Posted by Blake

Done.

The alternative theory is that it is all natural. And the evidence is “These results suggest that 20th Century warming trends are plausibly a continuation of past climate patterns. Results are not precise enough to solve the attribution problem by partitioning warming into natural versus human-induced components. However, anywhere from a major portion to all of the warming of the 20th Century could plausibly result from natural causes according to these results.”
Loehle, C. 2004; “Climate change: detection and attribution of trends from long-term geologic data.

And the IPCC itself says that pre-20th century events are plausibly natural and uninfluenced by humans.

So since you now have evidence of an alternative theory that that as accurately recreates the historical climate and conditions of things in modern times, do you reject Global Warming?
Of course you don’t.

You just made an assertion. You didn't provide evidence. If it's all natural, then modeling the climate with or without greenhouse gases included, tracking over the last century or three, should make no difference on the output.

So far as I'm aware, there's a good several dozen global climate modeling systems and not a one gives the same output regardless of the concentrations of greenhouse gases.

[DrDeth]

Originally Posted by GIGObuster

http://www.newscientist.com/article/...n-england.html

Hardly a "myth":
http://en.wikipedia.org/wiki/Medieval_Warm_Period
"The Medieval Warm Period was a time of warm weather around AD 800-1300 during the European Medieval period. Initial research on the MWP and the following Little Ice Age (LIA) was largely done in Europe, where the phenomenon was most obvious and clearly documented." Although it apparently was not a world wide occurrence.

http://www.grida.no/publications/oth...ar/wg1/070.htm
"As with the "Little Ice Age", the posited "Medieval Warm Period" appears to have been less distinct, more moderate in amplitude, and somewhat different in timing at the hemispheric scale than is typically inferred for the conventionally-defined European epoch. The Northern Hemisphere mean temperature estimates of Jones et al. (1998), Mann et al. (1999), and Crowley and Lowery (2000) show temperatures from the 11th to 14th centuries to be about 0.2°C warmer than those from the 15th to 19th centuries, but rather below mid-20th century temperatures."

[DrDeth]

Originally Posted by GIGObuster

Lord in the family sense, and nothing else, regardless of what he pretends to be. I would not have a beef if it wasn't for the fact that he is making an effort to pass himself as a member of the house.

Still, he is Lord Monckton, not "Lord" Monckton. And cite for he's trying to pass himself off as a Member of the Lords? Your cite "Private Eye" is more or less like citing "the Onion". A search of Google News has turned up nothing esle on the subject.

[GIGObuster]

Originally Posted by DrDeth

Hardly a "myth":
http://en.wikipedia.org/wiki/Medieval_Warm_Period
"The Medieval Warm Period was a time of warm weather around AD 800-1300 during the European Medieval period. Initial research on the MWP and the following Little Ice Age (LIA) was largely done in Europe, where the phenomenon was most obvious and clearly documented." Although it apparently was not a world wide occurrence.

http://www.grida.no/publications/oth...ar/wg1/070.htm
"As with the "Little Ice Age", the posited "Medieval Warm Period" appears to have been less distinct, more moderate in amplitude, and somewhat different in timing at the hemispheric scale than is typically inferred for the conventionally-defined European epoch. The Northern Hemisphere mean temperature estimates of Jones et al. (1998), Mann et al. (1999), and Crowley and Lowery (2000) show temperatures from the 11th to 14th centuries to be about 0.2°C warmer than those from the 15th to 19th centuries, but rather below mid-20th century temperatures."

Way to miss the point, the evidence is not there to show that it was a global phenomenon. The deniers used what it was an European phenomenon and have done their damnedest to make it global.

[GIGObuster]

Originally Posted by DrDeth

Still, he is Lord Monckton, not "Lord" Monckton. And cite for he's trying to pass himself off as a Member of the Lords? Your cite "Private Eye" is more or less like citing "the Onion". A search of Google News has turned up nothing esle on the subject.

Please check the logo Monckton uses in his paper against Al Gore:

http://www.hootervillegazette.com/LordMonckton.html

Compare it with the Official House of Lords one:

http://www.nio.gov.uk/media-detail.htm?newsID=7705

Dodgy indeed.

And it is noticeable that you are ignoring how unreliable Monckton is with his research.

[Sage Rat]

Originally Posted by Blake

So would you consider that the decline in temperature in the middle of the last century to falsification? Temperatures declined despite increased production of "climate gases"?

The IPCC report indicates solar output, volcanic emissions, and greenhouse gases as being the largest factors on the global temperature at any given moment. Changes in volcanic activity during the 1900s caused a drop of -0.5C between the first and latter halves of the century.

http://ipcc-wg1.ucar.edu/wg1/Report/...Print_Ch06.pdf (p. 477)

[DrDeth]

Originally Posted by GIGObuster

Please check the logo Monckton uses in his paper against Al Gore:

http://www.hootervillegazette.com/LordMonckton.html

Compare it with the Official House of Lords one:

http://www.nio.gov.uk/media-detail.htm?newsID=7705

Dodgy indeed.

And it is noticeable that you are ignoring how unreliable Monckton is with his research.

Sigh. You have no idea about heraldry do you? You found a attack site about Lord Monckton, one that cites a "fact" that no other source does, and you think that somehow that makes him not a "Lord". If Lord Monckton is violating the rules of Parliament and Heraldry, they will let him know. The British equivalent of "The Onion" is not a place for you to garner legit info or cites. Lord Monckton is indeed a Viscount, and thus he is entitled to use that crown.

And yes, I know I have not talked about his scientific work, but that's because somehow you think that attacking his title as spurious makes him a bad scientist. Which it does not.

[DrDeth]

Originally Posted by GIGObuster

Way to miss the point, the evidence is not there to show that it was a global phenomenon. The deniers used what it was an European phenomenon and have done their damnedest to make it global.

Let me make this point bigger for you "Although it apparently was not a world wide occurrence." I hardly missed it, I said it.

[GIGObuster]

Originally Posted by DrDeth

Sigh. You have no idea about heraldry do you? You found a attack site about Lord Monckton, one that cites a "fact" that no other source does, and you think that somehow that makes him not a "Lord". If Lord Monckton is violating the rules of Parliament and Heraldry, they will let him know. The British equivalent of "The Onion" is not a place for you to garner legit info or cites. Lord Monckton is indeed a Viscount, and thus he is entitled to use that crown.

And yes, I know I have not talked about his scientific work, but that's because somehow you think that attacking his title as spurious makes him a bad scientist. Which it does not.

The only thing I notice is that you do not read the cites.

See also his testimony [Monckton] to a US Congress Committee:

He again implies he has a seat in Parliament. Which he doesn't.

And no, the science blog is not looking at "The Onion" only.

The computer scientist at Deltoid has Monkton's number:

http://scienceblogs.com/deltoid/2009...the_future.php

God knows that I would prefer to see Monckton interviewed by the Onion rather than a Lyndon Larouche publication.

[GIGObuster]

Originally Posted by DrDeth

Let me make this point bigger for you "Although it apparently was not a world wide occurrence." I hardly missed it, I said it.

So what is the problem? The myth the article was dealing with was that deniers have used the Medieval warming period to say things like:

the Medieval Warm Period occurred with no significant human input.

When it is clear that that warming period was mostly an European phenomenon. Not specifying that it was in Europe is just an effort to lead others into thinking that the same warming was taking place in the whole world. That is the myth.

http://www.grist.org/article/the-med...warm-as-today/

There is no good evidence that the MWP was a globally warm period comparable to today. Regionally, there may have been places that exhibited notable warmth -- Europe, for example -- but all global proxy reconstructions agree it is warmer now, and the temperature is rising faster now, than at any time in the last one or even two thousand years.

Anecdotal evidence of wineries in England and Norse farmers in Greenland do not amount to a global assessment.

On its website, NOAA has a wide selection of proxy studies, accompanied by the data on which they are based. Specifically, they have this to say on the MWP:

The idea of a global or hemispheric "Medieval Warm Period" that was warmer than today, however, has turned out to be incorrect.