I'm not sure if they offer any criteria for disproof of the AGW hypothesis, but one site I've looked at a bit over the past day is skepticalscience.com. I was wondering if you had any thoughts on their page about the level of scientific consensus on warming here:
http://tinyurl.com/2htbkw
I note that the organizations they list seem to be predominantly connected to governments in one form or another. That doesn't mean they're wrong, but to me it lowers their chances of being impartial and objective, especially given the way the political class is trying to take advantage of the idea in such seedy ways as you gave an example of above. These people probably couldn't explain AGW in a scientifically plausible manner, but they want to tell the whole world just how to fix it and come out ahead despite the sacrifices? Give unto me a break.
The AGW hypothesis is obviously very hard to conclusively prove or disprove, since our inability to fully understand the climate system means that we can't make reliable specific predictions which are dependent on AGW being either true or false. I would change my opinion from "highly likely" to "unlikely" given either (preferably both) of the following:
(1) A convincing explanation of why the measured increase of atmospheric carbon dioxide, which is known to trap heat in the atmosphere, should not have a significant effect on the global climate.
(2) Statistically convincing evidence
that the long term global temperature trend has turned stable or negative. Unfortunately this would take at least (I guess) 10 years data and would be contentious for a long time.
I think you are probably right that people who are keen on economic regulation are likely to be overly accepting of the AGW hypothesis. Conversely, people who are highly adverse to economic regulation will tend to be dismissive.
The global temperature has stabilized over the last 7 years. You can find a good statistical analysis here:
http://rankexploits.com/musings/...recent-warming/
The gist of the argument is the weather trend since 2001 is either a 1 in 20 statistical fluke or evidence that IPCC is wrong. Each year that it stays stable increases the likelyhood that the IPCC is wrong.
If you want evidence that the effect of CO2 is overstated I would look here:
http://www.weatherquestions.com/...bal-
warming.htm
That blog explains how rising temperatures actually lead to more precipitation which acts like a natural air conditioner for the planet. The data collected by the NASA Aqua satellite over the last 5 years apparently supports this hypothesis.
James L. Regarding point 1, what do you make of the claims that the rise of CO2 in the atmosphere has historically trailed warming -- that is warming took place and then C02 levels rose. So that you do get an increase in CO2 levels but the cause is the other way around. And I know that Ive pointed to some scientific papers on how there was warming which resulted in the oceans belching large amounts of C02 into the atmosphere in the past.
On your second point: You say 10 years of data. I would be skeptical of 10 years of data given the way climates shift. I know there have been rapid warmings (and coolings) in the past, taking place within a few years time. But most such trends were over longer periods of time. We can see that the current warming trend, absent the recent stable or cooler years, went on since the mid 1800s. Now for the first 100 years of that it is assumed to be natural and for the last 50 years it is assumed to be man made. But it has been going on for sometime. But I do agree that each year that goes by with a stable or cooling climate makes the hypothesis less believable. And I would not be surprised if we see cooler global temperatures, at least over the next few years.
The advocates of the solar theory of warming have been saying that a reversal was coming any year now. Last year was clearly a reversal. And it is appearing that this year will be as well. And solar experts are predicting that solar activity over the next few years or decades will result in even lower temperatures. My feeling, for the last couple of years, was that within the next 10 to 15 years we will see which theory corresponds best with actual trends.
Regardless of whether human affected climate change is happening ("climate change," NOT "global warming," as according to the climate change advocates, SOME places will get warmer, others colder, some dryer, other wetter, ergo: climate change), sun affected warming is bunk:
http://www.badastronomy.com/babl...-the-sun-again/
I thought the advocates of warming were the "Greening Earth Society" and the Patrick Michaels set, who are saying "warming is actually good"...of course those guys don't know what could possibly falsify AGW 
Here's how to falsify AGW:
(A)
(1) Read the attribution studies on which the claim is based. Note what GCMs (models) are the foundation of the claims.
(2) See what those models predict given the forcings from the years in question. Compare the outputs to reality.
(3) If the models are way off, you can say that the attribution studies based on those models need to be revisited.
or
(B) Step up to the plate, do an attribution study of your own, do it better, and hope you can do it better without as strong an anthropogenic forcing.
There you go. Somewhat silly--no, downright insulting!--to insinuate that climatologists' theories are unfalsifiable. You cannot legitimately hold the views of an elected bozo in the third world against a scientific theory.
Very good, "Raven".
Have a look at http://www.realclimate.org/index...gswitch_lang/
in
The AGW theory is far from dead. Where's your attribution study? Come on, step up to the plate!
A quick comment from Mexico. Liam. The problem is that the global average got cooler not that Ļsome placesīdid and others didnīt. The entire average was down last year and for previous years it has been relatively steady.
Now I have seen some studies looking at IPCC models and what actually happened and there is somewhat of a difference. If that continues for a few years that means something.
Ben Please donīt assume I said that it canīt be falsified. What I said was that I havenīt seen any of the main advocates tell us what they would consider evidence to the contrary. I have seen the skeptics discuss things but I have never seen a warming proponent tell us what he would accept as evidence to the contrary. Have you.
YOu didnīt cite one merely implied I should come up with it. Well, my question is what will satisfy the proponents of the theory not the opponents and that still remains unanswered.
LiamW:
Umm... I have to say, your belief that solar forcing is not the predominant force for global mean temperature modification is actually quite silly.
I mean, seriously; talk about strawman arguments. The solar forcing argument is not and has not been tied to the brightness of the sun. To counter that argument is facetious.
I mean, seriously; there have been multiple studies which have linked climate variability to //sunspot activity//. Sunspot activity != solar brightness.
I don't usually put things this way, but... seriously: Get a fucking clue, man. If you're going to make a claim about a thing, at least get that thing correct.
BenK,
The GCMs are not a real world experiment and can only do what they are programmed to do. In this case, they are programmed with the assumption that CO2 is the only major climate driver so no one should be surprised to discover that the GCMs show that CO2 is the major climate driver. It is a completely circular and irrelevant argument.
The only way to determine whether the GCMs have any connection to reality is to see how well they predict the future. The last set models results published by the IPCC started in 2001 so we must use that as the starting point. Surprisingly, the models are already way off. Now, it will take another 8 years to actually falsify the GCMs but I don't think radical action on GHGs is justified given the evidence to date.
cls: "what do you make of the claims that the rise of CO2 in the atmosphere has historically trailed warming -- that is warming took place and then C02 levels rose. So that you do get an increase in CO2 levels but the cause is the other way around."
To me this indicates that CO2 levels can be both cause and effect of GW, and in previous episodes acted as a positive feedback mechanism. But I don't think there is much doubt that recent CO2 increases have been predominantly anthropogenic rather than a natural lagging response to earlier GW. It also implies that global warming can occur due to primary mechanisms other than CO2 increase, but that seems to be the prime suspect in this case.
On the second point: For the type of reasons you give, I find the climate data less convincing than the facts that CO2 traps heat and burning fossil fuels releases CO2. To me the global temperature plot looks a lot like continued gradual warming, obscured by a couple of El Nina/La Nina outliers in recent years, but it is also consistent with the start of a trend change. Pursuing the climate data argument further means looking at the various models and attribution studies, and either working through all the science personally or relying on authority to some degree. I have a lot more confidence in the professionalism of climate scientists than you - I feel that although individuals publicly disputing AGW may be dismissed as cranks, quality papers disputing AGW will be published - but that is still an appeal to authority.
I will be surprised if we get a cooling period in the next few years. I would be curious to know why the increase in CO2 failed to warm the planet, or what mechanism overrode AGW.
Raven (second link): This seems after a quick look to be a quite sophisticated (and peer-reviewed) argument which accepts AGW but argues that negative feedback will result in it having little ultimate effect. Of course there are known potential positive feedback mechanisms (water vapour increase, snow cover loss, methane release, CO2 release from oceans) and negative feedback mechanisms (cloud cover, presumably others). I'm not in position to refute this theory, so can only respond by saying that most published studies suggest that positive feedback will predominate.
James L says
"I'm not in position to refute this theory, so can only respond by saying that most published studies suggest that positive feedback will predominate."
At the end of the day the real data must rule. The current cooling trend could be a statistical fluke or it could be a sign that the climate science community has got some important things wrong.
That is why it is a mistake to rely on GCMs because they can never take the effect of unexpected unknowns like Dr. Spenser's negative cloud feedback into account.
Personally, I will be surprised if the planet does warm at rate which is anything close to GCMs predictions since phsyical systems dominated by positive feedback are very rare.
James L wrote:
I find the climate data less convincing than the facts that CO2 traps heat and burning fossil fuels releases CO2.It might interest you to know that there is a hard limit to the ultimate return on heat retention that can be caused by CO2. It absorbs only a small portion of the Infrared spectrum, and any heat-energy that is not of this spectrum is completely transparent to CO2.
We all know that there is a powerful thermal retention signature to our atmosphere. The question at hand is whether or not the human contribution to the atmospheric content of thermal retaining materials is capable of overwhelming the natural mechanisms.
And the truth is, there is literally no humanly possible way to know that question. There is, however, some fairly solid evidence that it is not the case: amongst others you can find this graph. (Source reference for the graph here.)
The simple truth is that the trendline for GMT (global mean temperature) for the last eight years has a negative slope (i.e.; decreasing over time). ALL GCM's (global climate models) have predicted an upwards trend for this period.
The lowest expected change from the GCMs is well //above// the highest rate of error for the experienced sequence of events.
This is proof positive that there is something very wrong with the statistical models; eight years of continual change is too powerful a trend to be accepted as anything else.
I mean, think about it. For the first time in recorded human history, it has snowed in Bagdad. This at the same time as both the northern //AND// southern hemispheres had record ice cover accumulation.
Since ice-cover is supposed to be a positive feed-back with GMT increase, more ice-cover obviously means lower temperatures over time. So we can expect even //further// cooling ahead.
In short: at this time, the human contribution is clearly and demonstratively NOT capable of overwhelming the natural regulatory cycles of the earth.
CLS: What will satisfy the scientific proponents is an attribution study which tops the ones on which the current view is based.
What will satisfy the non-scientific proponents is seeing scientific authorities change their minds.
Raven: The IPCC does not publish attribution studies, moreover, your insinuation that the GCMs are programmed with the answer is without base, however true it may be that the forcings and feedbacks in the GCMs are the forcings and feedbacks in the GCMs and not some other set. If you would for some good reason use different forcings and feedbacks, I recommend that you do it and write a paper reporting the results and justifying your choice. Waving your hands, trying to turn the truism that models are based on known physics (assumptions) into an argument against the models is not a good way to make your case.
Raven: To not rely on models because no model can take into account "unexpected unknowns" is to dismiss all of science altogether.
What if Baby Jesus wants photons to scatter off of each other in Toledo but not Cincinnati? What if the universe enters a new vacuum state tomorrow and full valence becomes 9 electrons?
Ian C:
I have yet to see a good study that links global climate to sunspot activity, let alone to such a degree that one could say that the AGW thesis is without merit. It isn't for lack of looking.
Scaffeta and West (who embarass themselves with an hilarious, scare-quote-filled, intemperate column in this month's Physics Today) are doing something interesting, but being a skeptic by nature, I'm not apt to treat it as anything more than the somewhat sloppy preliminary work that it is. The methodology shows long-term promise, but the authors seem interested in treating the preliminary result as the new sine qua non of climate attribution. Given their remarks in PT, there's reason to suspect that even they know they're not conducting themselves in accordance with community standards of honesty and modesty.
Rasmus Benestad, among others, has shot the work full of holes, fairly definitively. If I were Scaffeta and West, I'd be back to work fixing what's broken. I wouldn't be cocky and borderline ideological in the pages of PT!
If I get a spare block of time, there's a question about uncertainty propagation--they have the difference of two fairly close numbers in a denominator--that I'd like to investigate. That I have the question doesn't mean they did it incorrectly.
BenK says:
"The IPCC does not publish attribution studies"
Then I wonder why Chapter 9 is called "Understanding and Attributing Climate Change".
http://ipcc-wg1.ucar.edu/wg1/
Rep..._Print_Ch09.pdf
I am not going to waste time with an argument about the meaning of the word "publish".
BenK says:
"moreover, your insinuation that the GCMs are programmed with the answer is without base, however true it may be that the forcings and feedbacks in the GCMs are the forcings and feedbacks in the GCMs and not some other set."
GCMs may be based on physics but they also rely a lot on parameterizations and must be tuned to produced a reasonable result. These parameters cannot go outside of certain physical limits but even then they have a wide range and give the modellers lots of flexibility. This tuning process ensures that the GCMs produce only the results expected by their makers.
For example, lets say the solar theories are right and 75% of the recent warming can be attributed indirect effects to the sun. A GCM programmed to assume that the sun has no effect could never be used to demonstrate that the sun has a large effect. It is a useless circular argument that I getting really tired of hearing.
OTOH, we can look at the real world data and compare it to the predictions made by a GCM programmed to believe that the sun has no effect. If this GCM predicts the future correctly then that GCM has merit. If the predictions are off then that is a sign that the GCM is wrong and we need to reconsider the assumptions.
The bottom line is: GCMs are useful tools but they should *never* be used as the basis for any policy decisions unless they have be shown to correctly predict the future.
Rigorous statistical tests on the temperatures in since the start of the latest IPCC model predictions now show that the models are most likely wrong (95% certainty).
Please explain why we should make massive social investments based on models that are only have a 1 in 20 chance of being correct given the data available today?
James L: You say that you concludle CO2 levels can be both cause and effect on GW. You also say there is no doubt that CO2 increases have been mostly anthropogenic. How do you know this? The warming trend started about 100 years ago. The major CO2 increases much more recently. Could it be that CO2 was already rising and due to warming and that human impact in the last 50 years is relatively unimportant compared to a larger natural fluctuation? We do have the classic past pattern repeating itself of warming first followed by C02 increases.
To illustrate we could have someone killed if we throw big rocks on them. If someone were walking and someone threw a normal rock in his direction, while a landslide happens to hit him at the same time, would we necessarily assume the thrown rock was the culprit? Or was it coincidental that it took place and that a larger natural event overwhelmed the man-made event?
You will be surprised if we get a cooling period in the next few years. Well, we are already in one. The question is for how long. Of course the modelers say it is La Nina, which no doubt is involved. Yet when they pointed to previous warm years those were coincidental with El Nino. Yet those extra warm years were blamed on warming not El Nino -- which often got no mention at all. Very double standard there.
Regarding the models. My concern is similar to when police investigate a crime and think they have a suspect. They tend to concentrate on the evidence that supports their thesis and ignore contrary evidence. They try to get the facts to fit the theory and not the other way around. Models are extremely complex things. If you have literally thousands of factors, and you are in the dark about many of the factors, you might well model some factors as being of more importance than they are. There are lots of guesses and judgment calls involved. But that gives the modeler a lot of room of unintentionally push some factors as more important than they are because he assumes that is the case.
So the model cant tell us anything off the bat except that the modeler added in factors he thought important and excluded or reduced factors he thought less important. So before you decide the model is correct you have to compare the model to actual reality and see how well it does in predicting the actual trends. Admittedly the models have become better and better, that is they have become closer to reality. But as they came closer to reality they also become less startling and alarmist.
Now I suspect the time will come when the models and reality correspond fairly well. When that comes we can then use the models to decide public policy. Perhaps when that time comes the alarmist side will be ahead, though not by as much as they assume at this time. Perhaps not.
Smart work about global warming. I have also a blog which give information about cause of global warming.
Raven:
Your use of the word "correct" and this talk of a 1/20 chance shows that you really don't understand the nature of scientific arguments, and there's thus no sense arguing with you.
We're not dealing with a boolean question and nobody expects the models--or attribution studies--ever to reach some "correct" ideal.
-BSK
CLS says:
Regarding the models. My concern is similar to when police investigate a crime and think they have a suspect. They tend to concentrate on the evidence that supports their thesis and ignore contrary evidence. They try to get the facts to fit the theory and not the other way around. Models are extremely complex things. If you have literally thousands of factors, and you are in the dark about many of the factors, you might well model some factors as being of more importance than they are. There are lots of guesses and judgment calls involved. But that gives the modeler a lot of room of unintentionally push some factors as more important than they are because he assumes that is the case.
It's rather difficult for BS and dishonesty to survive very long in the scientific discussion. If you have found a flaw in one of the major attribution studies, let alone one that would cast AGW into categorical doubt, I suggest that you write up what you found and send it as a "letters" or "rapid communication" paper to the journal in which the study in question was published.
Can you point me to a particular attribution study and tell me where this is being done? Is this a concern based on your reading of the attribution studies or is it one of those things that should be a *question* on your part, the basis for "I don't know but would like to", not the basis for "the experts are wrong and I can thus believe whatever I want."
Raven: The IPCC references attribution studies. The IPCC does not publish attribution studies. The IPCC is not a technical journal. That you make such a silly argument furthers my doubt that you're willing to learn enough about this matter to discuss it intelligently.
Ben K says:
"Your use of the word "correct" and this talk of a 1/20 chance shows that you really don't understand the nature of scientific arguments, and there's thus no sense arguing with you."
I am sorry but it is you who do not understand the nature of science and statistics.
The climate models make predictions regarding the climate based on certain assumptions. If their predictions come true then we have reasonable confidence that the assumptions are correct. If they turn out to be false then we know that their assumptions are wrong.
Attribution studies based on past climate are nothing more than a way to demonstrate that assumptions built into the model are reasonable. Attribution studies DO NOT prove that the assumptions are correct. The only way to show that the assumptions are correct is to validate the model predictions against reality.
Unfortunately, the nature of weather variability makes it impossible to be 100% certain whether a prediction has come true or not. That is why it is necessary to use statistics to determine the probability that the prediction was correct.
A proper statistical analysis applied to the current cooling trend shows that the models 95% likely to be wrong.
Now wrong could be many things. Perhaps they underestimated the effect of the solar cycle but the underlying trend is still correct. But it could also mean that underlying CO2 physics is completely wrong. We don't why the models are wrong - we just know that they are most likely wrong.
The bottom line is we should not be making radical public policies decisions based on computer models which are most likely wrong.
Here is an excellent layman summary of the latest peer reviewed research and data and explains the scientific basis for what we can already deduce with statistics:
http://wattsupwiththat.wordpress...global-warming/
Humans are so vain. We have weather data for a couple hundred years out of 4 billion and are willing to subject this country to sanctions on the free market. Perhaps we need more CO2 emissions to prevent the next ice age.
Mr Locke: In light of your psuedoracist langauage elsewhere I would appreciat NOT having your support.
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