Thursday, 15 May 2008

Sunspots and Climate

It is bizarre that anyone is claiming that we should be basing climate models on sunspots at all. What is important is how much energy is incident on the planet, and how the overall energy balance changes. Sunspots may be a proxy for solar output, but we have direct measurements in the modern era, specifically satellite-based measures of total solar irradiance (TSI).

Nonetheless the thing persists.

In April 2008, an article appeared in The Australian alleging there had only been 3 sunspots since January and hence we were headed for an ice age. This article was rebutted by Melbourne academic David Karoly. On 15 May, a letter appeared in The Australian, claiming that Karoly had confused sunspot number (a calculated value) with number of sunspots. It's possible Karoly did, though he was correcting the previous article's manifestly wrong claim that there had only been 3 sunspots in total over a period when there had been many more.

This latest letter claims:
One visible sunspot is represented by a sunspot number of 11. Karoly writes that “the average number of sunspots a day last January was 3.4, followed by 2.1 in February and 9.3 in March’’. In fact, those numbers show months with many days of zero observed sunspots - a very quiet period on the Sun that has now extended longer than expected. Whether that affects the weather cannot be so easily disregarded as does Professor Karoly.

There does seem to be an interesting correlation between the length of sunspot cycles and climate change going back over centuries, compared with the 150 years that is all the CO2 warmers can work with.

There are several problems here.

For a start, it is incorrect to say that a sunspot equates to the number 11 in sunspot numbers. Let's see what the actual definition of sunspot numbers is:

An observer computes a daily sunspot number by multiplying the number of groups he sees by ten and then adding this product to his total count of individual spots... each daily international number is computed as a weighted average of measurements made from a network of cooperating observatories.

That is a nitpick of a nitpick so I will not dwell on it. The substance of the matter is his claim that sunspot cycles are a much better indicator of climate trends than modern models. Aside from the issue of more direct measures of solar output, the last sentence is bizarrely off target. Why should it be better to have centuries-long data of a phenomenon that did not exist centuries ago?

Anthropogenic carbon dioxide emissions began in earnest in the 18th century; by the close of the 19th century, they were less than 10% of current levels.

Saying that sunspot counts stood us in good stead for centuries so we should disregard other measures is like saying horse riding techniques stood us in good stead for centuries, so someone learning to drive a car should go to a riding instructor. In any case, the "centuries" claim is a tad inaccurate. The modern method of counting sunspots was invented in 1848.

Then there's the question of whether sunspot numbers actually correlate to the modern temperature trend. The IPCC has always stated in its reports that climate is a function of natural and anthropogenic influences, and even shows them separated out (here's a paper that does this nicely – see Figure 2(d) in particular, reproduced here). We would expect that solar output could be a major influence on climate before CO2 emissions became a major factor. But in recent years, this is not the case. In fact the trend in solar output is the opposite to that required to explain the warming trend in the late 20th to early 21st century.

If anyone asks nicely, I may even add in a few correlations.

But in the meantime, here is where you can find the data:


Climate Chaos said...

Sunspots are a proxy for solar output. But, the real factor is what type of radiation is reaching the earth and in what form. The sunspot correlation is relatively ok.

But total radiation is not the final answer. Some of the radiation might be ionizing to the upper atmosphere resulting in more higher clouds, and less solar radiation entering the atmosphere. The sunspot guys discuss this.

My problem with the CO2 people is that there models haven't worked and are not predictive. They assume a constant solar input, which is definitely not the case. It has not warmed for the last 10 years, but the CO2 is up significantly? The oceans have cooled. The models never worked and they started fudging them with other stuff to try to make them back correlate, but they still are not predictive.

Plus, water is the real green house gas. The models don't properly handle water. We could go on.

My core point is, read more about the contribution of variable solar radiation.

Philip Machanick said...

climate chaos, please point me to one climate model using CO_2 which assumes constant solar input. The serious climate scientists include all known influences, natural and anthropogenic.

Please also see another article on this site where I address the issue of predictive power of climate models.

There is some debate about the net effect of clouds but water vapour itself is well understood and fully included in the mainstream models.

As to your assertion that is has not warmed in the last 10 years, see another article on this site covering that point.

Anonymous said...

First off TSI does not measure the second order effects such as magnetic influences on cloud formation.

The true strength of the solar model, however, is that it predicted the current cooling while the CO2 models did not. In the end all that really matters in a scientific theory is how it predicts empirical reality.

What we need to do is stop arguing who is on what side of the mainstream and instead focus on the real scientific task of testing theories against actual observations.

Anonymous said...

And Phillip, you might have noticed that this short term "variation" was discovered by the CO2 theories POST FACTO...

It was only after the predicted warming failed to appear that they changed their theory post facto to include it. At the same time they had the unbelievable gall to say they were right all the time.

Philip Machanick said...

"Anonymous", please give a name, otherwise I don't know if all the comments are the same person or not.

Sunspots or TSI do not correctly model temperature variation. I looked at the data from 1975 to present when the warming trend is clear, and we have sunspot numbers and (for most of that period) satellite TSI.

Over that period, solar output is more or less flat (undulating but no obvious trend to the eye). Papers have been published showing that in recent years, any trend in solar output is the opposite to that required to explain the temperature trend. You'll find them cited at WikiPedia.

Where do you get that short-term variation was discovered post facto? It's in the HadCRUT3 data going back to 1850. That's what I would be looking at, not claims by climate scientists. In any case, can you give me a reference to a paper that says that all temperature variation is driven by CO_2? All studies I've read includes natural + anthropogenic forcings. Show me the one that doesn't and I can publish a rebuttal because it's obviously rubbish. Given natural variability, why would you expect warming to be continuous, with no short-term undulations? I address that in more detail here.

As you say, one should look at the evidence.

You say "models haven't worked and are not predictive". What's your evidence for this? I took a look at Hansen's much-cited 1988 paper for example, and found his prediction for what he considered the most likely scenario was well within the error bars of subsequent measurement. I did this independently for my own satisfaction because there's a limit to what I take on trust; this has been done more formally at RealClimate. If you google "IPCC validate past models" you get a lot of blogs echoing your claim. If you focus your search down to actual IPCC documents you will find that they do in fact validate past predictions (e.g., the Fourth Assessment Report examines the predictive power of models used in the Third Assessment Report -- see e.g. p 98 of Chapter 1 of AR4).

As for the cosmic ray stuff: if a combination of the sun + CO_2 as predicted by the models fits reasonably well, why do we need to worry about what has yet to be shown to be at best a second order effect?

Buono said...

The sun radiates energy in a wide spectrum of wavelengths. Some lambdas may be captured by our atmosphere and transduced into heat at earth surface level some others would tend to destroy our upper atmosphere or to escape away.
Hence the statement that the overall energy radiated is related to the surface temperature on the planet is a simplistic model. Sunpots number and duration may have an influence on our climate (magnetic fields ?? other ??). We do not know so as we do not know how much of the radiated energy is captured and transduced into heat at planet surface. I do not know if there are objective tests and suspect is that there may be a lot of inference around.

Philip Machanick said...

Buono, what's your evidence for your statements? If you have references please post pointers, otherwise it's just an opinion. The mainstream climate models capture the overall effect of energy flows pretty well, give or take that ocean modelling is still relatively primitive. The sort of effect you are proposing is unlikely to be more significant than the errors of inaccurate modelling of heat transport into the oceans, which take up over 80% of changes in energy flows.

Philip Machanick said...

One Greig here (a bit late for me to get in a response, hence the reply here) criticises this article for not showing the last 8 years in the graph, which he alleges "doesn’t include the last 8 years of data (ie no warming)". I haven't found a similar graph covering more recent times but the warming trend has slowed, rather than reversing as he claims. If indeed there was no anthropogenic effect, why is has the temperature trend not dipped lower? Most years since 1998 are still above anything before 1998.

In another post, he says "Roy Spencer of the University of Alabama has submitted a paper which shows a statistical correlation (with 94% confidence) between 100 year temperature trends and combined SOI and PDO". That looks very much like this one, debunked at RealClimate.

Greig said...


You have made several false statements that require correction. At no stage have I stated that in the last 8 years the globe is “cooling”, nor have I stated that the warming trend has “reversed”. I expect that in any response to me you will retract those comments.

What we both know is that the warming trend has significantly slowed, and you acknowledge that. My point is, why has this occurred, when CO2 continues to rise? How does that impact the basis of global warming observation which has relied on a correlation between rising CO2 and temperature? How would the slowing of the warming trend be explained if anthropogenic causes are a significant factor? How would the Meehl et al analysis look if the last 8 years of data was included? You know the answer, you are obfuscating to avoid addressing the issue.

It is obvious there are significant natural factors at work, that have yet to be fully identified. These factors cannot be ignored, they may mean we do not need to panic about global warming. We may be able to avoid unnecessary waste of resources on poorly implemented mitigation strategies.

Yes, you have the correct Spencer paper. I note the so-called debunking has presented absolutely no comment on the thrust of Spencer’s hypothesis concerning internal radiative forcing, and has only commented on the manner in which Spencer created a single graph. You call that debunking? You really ought to spend a bit more time doing real science instead of believing everything you read on ReallClimate.

Spencer is a genuine climate research scientist, with plenty of peer-reviewed papers under his belt, and he is not biased by money. He does not deny the obvious existence of some human influence on climate (nor do I), but Spencer genuinely believes that the IPCC predictions of catastrophic climate change are wrong, or at least overstated, because they ignore important negative feedback mechanisms. Spencer is in good company, there are many scientists who hold similar beliefs, and have peer-reviewed literature to substantiate their position, Richard Lindzen and Bing Lin for example.

I read your responses and web page. Despite your passion for and knowledge of this subject, you have a clear bias for believing only what satisfies your pre-conceived notions about climate change, relative to your political views. That is not unusual. But it is a pity.

Anonymous said...

Blogs like this, with at least one informed person willing to patiently correct misconceptions, are important for helping the educated lay person understand climate change.

But I think it is a pity that some bloggers feel compelled to impugn the motives of those they disagree with. This is an annoying distraction for those of us trying to understand the issues.

Thanks heaps for the blog though.

Greig said...

[PM] "As for the cosmic ray stuff: if a combination of the sun + CO_2 as predicted by the models fits reasonably well, why do we need to worry about what has yet to be shown to be at best a second order effect?"

How do you know the "cosmic ray stuff" is a second order effect?

The problem is that sun+CO2 only correlates with the data from about 1970 to 2000. After that, the correlation starts to look very shaky if CO2 is a major driver. That is why the "cosmic ray stuff" is important research. It is possible that cosmic rays + sun is a first order effect and greenhouse warming is a second order effect.

Anonymous, I agree that PM is knowledgable on this subject and generous with his time, but he is also clearly a one-eyed supporter of AGW, and shows a lack of objectivity. I would not normally be so pointed and personal in my criticism, but PM misquoted me, and he deserves a kick in the pants for that.

Philip Machanick said...

Greig, sorry about converting your "no warming" statement into something stronger. At least I put it somewhere that allowed replies: The Australian is annoying in that you never know when they will close comments.

I would be only too happy if you were right but unfortunately science is not built in sentiment. I was involved in other similar debates in the past -- the effect of tobacco on health, the group of people who claimed HIV doesn't cause AIDS -- and the arguments were very similar, with a strong component of the contrarian argument based around a small disgruntled group claiming they were Galileos and everyone else was the Catholic Church.

What I learnt from those experiences is that a guerrilla attack on science can be very effective with remarkably little substance. I know that there are some genuine climate scientists asking legitimate questions about the mainstream, but most of these questions ultimately either lead nowhere, or lead to small corrections. On the other hand there is a huge flood of easily-debunked rubbish from people who don't want to be forced to change their lifestyle or line of business. The resistance to the kind of change demanded to deal with climate change is likely to be so significant that it will sabotage taking adequate action.

So I really, really hope you are right. Unfortunately this is not a matter of religion or political ideology. If the mainstream is right, we don't have much time to turn things around. Hence my attempts at doing my own analysis where I can (as you'll find on other pages here) to make sure that the theory is sound, to the extent that I can with limited resources.

If you want a more detailed debunking of Spencer, try this. If you can cut through some of the less temperate comments, the science discussion is as detailed as you want it.

As far as your question on why it isn't getting warmer as fast since 1998 goes, I have a detailed discussion here on how short-term variation can obscure long-term trends. Another thing to consider: the anthropogenic greenhouse effect is overlaid on natural influences such as the sun, and we are close to the minimum of the 11-year solar cycle. I don't have access to the latest climate modelling but the solar cycle may point to an answer to your question, "How would the Meehl et al analysis look if the last 8 years of data was included?" I also suggest you read the 2008 paper by Lean and Rind. It doesn't have a nice picture but it does have some careful work teasing out the various influences on the climate system.

The cosmic ray stuff is heavily disputed and there are papers showing that some of the work claiming strong correlations is not statistically valid (see e.g. this response).

Also, the response of the climate system to greenhouse gases isn't linear. The basic effect is logarithmic in CO_2 concentration (originally reported by Svante Arrhenius in 1896). You may notice some people in the anti-global warming camp claiming it's a mystery that the response isn't linear. That they are not up with 20th century science is bad enough. That they are behind on 19th century science is even worse. It is this grasping at anything that supports the case no matter how easily debunked that makes it very hard for me to see that there is a serious case against AGW. If you go to sites like RealClimate, you will see that everyone who posts factual errors is slapped down, whichever side of the debate they are on. That is science. Insisting your are right and accepting every argument no matter how flawed is not.

I have a question for you to consider. Increased greenhouse gases trap more energy in the system. A change in the earth's orbit bringing it closer to the sun adds energy to the system. The climate system doesn't know where the extra energy came from. It should therefore make no difference. Why then in past interglacials, when energy has increased through the earth moving closer to the sun, should the effects of more energy in the system be any different? Yet people like Lindzen are trying to tell us that our situation is different, and negative feedback from clouds will somehow limit the extra energy effect of greenhouse warming. I'm not an MIT professor but this sounds like bunk to me. What do you think?

Greig said...


Firstly with regard to the last 10 years of warming. You are correct, 10 years of “no warming” does not mean a reversal of the trend. However, it should be recognized that the bulk of the evidence for global warming arises from a 30 year data set, from 1970 to 2000. I would argue, this is also an insufficient timescale to demonstrate a correlation. You have already proved this to yourself, when you plotted the trend for 1850 to 1900. My argument is, if the basis for AGW relies on a correlation over a 30 year period, and you present as proof of AGW papers like Meehl et al which uses this data, then the addition of an additional 8 years of data is relevant. And if you add the last 8 years of data, then the analysis presented by Meehl et al collapses. That’s science.

Regarding the further “debunking” of Spencer, I remain unconvinced. The arguments against Spencer are over his assumption regarding the rapidity of the heat transfer process. Yet with regard to oceanic circulation, his assumption of the depth of the mixed layer is well supported by the literature. And although his assumption of rapid feedback mechanisms arising from tropical clouds formation and evaporative cooling (see Lindzen’s IRIS theory) is not yet fully proven, the data from NASA’s Aqua satellites is compelling. In that sense, I believe Spencer is getting ahead of himself, but in another sense that potentially puts him ahead of the curve. A dangerous practice for scientists, but tell that to Einstein. In short, I am convinced that Spencer is onto something important here, and he should not be so quickly dismissed.

In answer to your question, you base this on a false assumption about heat input from the sun in reference to orbital changes. It appears that you do not understand Milankovitch cycles. The passage from ice age to interglacial warming does not occur because the Earth is closer to the sun and so receives more heat. It occurs because the Earth changes its eccentrity, and precesses, axially tilting so the Northern Hemisphere winter and summer solstices coincide with the perihelion and aphelion respectively. The total heat received by the Earth does not change, it just receives it at different intensity at different times of the year. The main reason these changes cause a warmer globe in an interglacial are (1) ice in the northern hemisphere is reduced, so there is a lower albedo effect, and (2) the current positioning of land masses means that ocean circulation is distributing heat differently at different times in the Milankovitch cycle. The latter is a major factor and is very poorly understood at present, which is why Spencer, Lindzen and many other scientists view oceanic circulation, and cyclical climate indexes (like the SOI and PDOI) as critical to understanding long-term natural climate trends.

Also, you refer to Lindzen and his theories on cloud formation. At no stage does Lindzen suggest that the overall heat budget is changed by clouds. Instead, (to put it very simply) he hypothesizes that as greenhouse forcing increases, evaporative cooling (the rapidity of heat redistribution) and the formation of tropical thunderheads convert water vapour to ice (hail), and so presents a negative feedback mechanism. This does not negate greenhouse warming (and Lindzen makes no such claim), rather he contends that this reduces the substantial acceleration factor from increased water vapour which is assumed in the current IPCC models, which leads to it’s alarming worst case temperature rise predictions. If Lindzen is right, then business as usual warming may be only 1-2 degC over the next century, which will result in no net negative environmental impact.

Greig said...

Science is one thing, but politics is involved whether we like it or not. The constant reference to “scientific consensus” is symptomatic, since as you know science is not issue subject to consensus which is a solely political notion.

I take your point about vested interests using “guerilla tactics” to misinform the public. It has certainly happened before, in particular with regard to tobacco and health. However, in the case of climate change, your comments appear to be throwing the baby out with the bath water. True climate skepticism (as opposed to so-called “denialism”) is not arguing that climate change is not real, or that CO2 does not cause warming. The true skeptics are arguing against the alarmism, as presented by Al Gore, Tim Flannery, etc that AGW will cause catastrophic environmental damage. The skeptic merely argues that the jury is still out.

For example, with regard to tobacco and health. The scientific support for negative health implications for smokers is undeniable. And it is now almost fully accepted in the community. However, there is little evidence to suggest that passive smoking has negative health implications, there is almost no credible scientific evidence for it. Yet it is assumed in the mainstream that passive smoking is bad. So what? There is now a raft of legislations based on controlling passive smoking that has huge implications to small business. This results in unnecessary costs which are borne by consumers, and wasted resources. And this has occurred because politics has trumped scientific process. Exactly the same thing is happening with AGW legislation.

My belief is that there is very good scientific evidence existing today, and growing with the work of people like Spencer, which proves that AGW will have a relatively small net negative impact on the environment, and that attempts to “turn it around” by prematurely applying the precautionary principle will have massive negative impacts (eg on addressing deforestation, biodiversity and human overpopulation). By overlooking or dismissing the apparent minutae in the process of scientific discovery on AGW, we risk making big policy errors.


Philip Machanick said...

Greg, I don't have time to check through all of this. Just a few points. I don't believe it's correct to say that climate science is only working with 30 years of correlation. For a start, the climate models are based on physics, not correlation. Secondly, they are based on a combination of hindcasting and forecasting. You may argue that hindcasting can be faked, models can be overfitted to the data, etc. but it's extremely unlikely that many independent modellers using different techniques would arrive at the same erroneous forecast as well as fitting to past data. Not impossible but very unlikely.

It seems we agree on the last ten years: we can't really say anything about so short a time. However you go on to presume that the Meehl et al case collapses without seeing the data. We know temperature increase has slowed over that period. We also know solar output is on a downward trend over that period. What we don't have is an extension of the graph showing how these (and other influences) change the output of the models.

On Milankovitch cycles: thanks, I'll look into it further.

Of course it would be great if you were right. However, if you really want to be a good sceptic, how about spending a bit of time looking at the evidence that things could be worse than the mainstream predictions? For example: there's a growing body of literature on the possibility of a very rapid meltdown of the major ice caps.

On tobacco: if you've made your mind up no doubt you can't be swayed but try reading this anyway:

Elisa K. Tong, MD, MA; Stanton A. Glantz. Tobacco Industry Efforts Undermining Evidence Linking Secondhand Smoke With Cardiovascular Disease, Circulation, vol. 116 2007, pp 116:1845-1854.

(you may need access to a library that subscribes to the journal to read it). I think I am safe from the copyright police reproducing the abstract, but you really want to read the detail:

Background—The scientific consensus that secondhand smoke (SHS) increases cardiovascular disease (CVD) risk by 30% is based on epidemiological and biological evidence. The tobacco industry has contested this evidence that SHS causes CVD, but how and why they have done it has not been described.

Methods and Results—About 50 million pages of tobacco industry documents were searched using general keywords and names of industry consultants and scientists. Tobacco industry–funded epidemiological analyses of large data sets were used to argue against an epidemiological association between SHS and CVD and smoke-free regulations, but these analyses all suffered from exposure misclassification problems that biased the results toward the null. More recent industry-funded publications report an increased risk of CVD associated with SHS but claim a low magnitude of risk. When early tobacco industry–funded work demonstrated that SHS increased atherosclerosis, the industry criticized the findings and withdrew funding. RJ Reynolds focused on attacking the biological plausibility of the association between SHS and CVD by conducting indirect platelet aggregation studies, exposure chamber experiments, and literature reviews. Although these studies also suffered from exposure misclassification problems, several produced results that were consistent with a direct effect of SHS on blood and vascular function. Instead, RJ Reynolds attributed these results to an unproven epinephrine-related stress response from odor or large smoke exposure, which supported their regulatory and “reduced-harm” product development efforts. Philip Morris’ recent “reduced-harm” efforts seem supportive of a similar corporate agenda.

Conclusions—The tobacco industry attempted to undermine the evidence that SHS causes CVD to fight smoke-free regulations while developing approaches to support new products that claim to reduce harm. The industry interest in preserving corporate viability has affected the design and interpretation of their cardiovascular studies, indicating the need for great caution in current debates about future tobacco industry regulation and development of reduced-harm tobacco products.

Greig said...

I disagree completely with your view that the AGW hypothesis is not based on observed correlation. To state otherwise is to deny the fundamental requirement for observation in the scientific process. Climate models are indeed based on physics, but they are also based on assumptions which are certainly tweaked to match the observations. That is how climate models work. I am afraid you and I are going to have to agree to disagree there. I think if you can take the time to consider my opinion on this, you might have a better idea of why I (and many other scientists) have (based on the last few years of observation) become so skeptical of mainstream AGW science.

Also, the Meehl et al analysis under its base assumptions definitely collapses when you include the last 8 years of data, in my mind there is no debate there. However I do not deny that the analysis can be adjusted to match observation, by either lending greater weight to the role of solar input, less weight to anthropogenic effects, or adding other unspecified natural factors such as ocean circulation and negative feedbacks. And there would be no problem with that, that’s how science works. And that is my very point. Current observations suggest there is far more to this than currently resides in the mainstream, the jury really is still out. And note that the IPCC 4th assessment is based on data that is more than 8 years old.

I am quite aware of some of the emerging suggestions about catastrophic polar ice melt. But I am very skeptical, because it doesn’t match with the paleo-climate observations.

On tobacco, you have presented a paper that assumes that there is a scientific consensus on passive smoking, but does not provide the basic science to support that consensus. Indeed any paper which places science and consensus in the same sentence immediately raises my hackles. The concept of consensus is meaningless in science! I await your posting of real peer-reviewed scientific study linking passive smoking and health effects.

Philip Machanick said...

Greig, did you read the tobacco paper? It was a study of the methodology tobacco companies used to undermine the process of developing policy from the science by tactics such as defunding research that didn't produce results they agreed with.

There are papers describing rapid melts in the paleoclimate in the last 200,000 years. For example, one in Science in 2006. This doesn't mean it will happen now, but it does mean that there's a case to investigate ice sheet dynamics with some urgency.

But let me issue you a challenge: I've examined a lot of climate science papers containing projections (e.g. here), making them amenable to validation against future events. If they were just curve fits as you claim, they wouldn't fit future measurements (allowing for error terms in the paper and error bars in the measurement). Those I've checked have generally fallen in the error bars. I've also read a fair number of papers claiming that they have another explanation for the climate system. These latter papers are the ones that look to me like curve fits, and I have yet to see one that contains a verifiable projection, with a follow-up study showing that the projection was accurate.

Spencer's paper for instance, with a 2008 date, stops at 2006. It makes no attempt at forecasting. Soon's 2005 paper claiming that he could explain everything by solar variation was statistical manipulation, with no attempt at modeling the physics and no attempt at forecasting.

So: tell me where you have seen any paper that claims to refute the "consensus", contains projections, and was published long enough ago that its projections can be verified against subsequent events. I'd be really interested to see it. You've accused me of being "one-eyed". I've applied the same standard to research from both sides. All I ask is that you do the same.

One more thing to consider. We've been in quite a large La Niña phase since around February 2007, which would normally be a low point in natural variability. Despite the slowdown in warming, 2008 is still looking like maintaining temperatures that would have been a record or near-record before the big El La Niño year of 1998. In other words, if things are a tad cooler this year, it's not because we are on a downward trend but because we are in a low in a standard cycle in natural variability. See January and later reports. El La Niño and La Niña are ocean heat transport events and unrelated to the greenhouse effect or solar variations (except to the extent that large-scale climate change interferes with ocean dynamics).

Greig said...


The fact that tobacco companies as a vested interest are attempting to corrupt the scientific process is not proof of a link between passive smoking and health. And just because there is a consensus of opinion that there is a link between passive smoking and health, also does not mean that it is proven. It is the same with AGW. Consensus of opinion is meaningless in science, and simply because the fossil fuel industry has a vested interest in AGW being unproven, it is not evidence that AGW is proven.

Regarding rapid ice melt, the paper you have presented does not show that there is any evidence in the paleoclimate record, rather it references an article in Science by Thomson et al, which if you follow it up shows that glacial ice melt actually occurs on a millennial scale. ie it really depends on what you mean by rapid. But far be it from me to suggest that research of ice sheets is unnecessary.

Nobody doubts that there is an apparent correlation between CO2 and temperature in the latter half of the 20th century, and Hansen’s 1988 graph is simply a statement of that correlation. Hypotheses can be tested by either fitting the past or by their ability to predict the future. Both are adequate ways of verifying the hypothesis against observation, and I disagree that simply because a hypothesis does not attempt to predict the future, that it is necessarily weak. Consider the fact that at present we have no way of accurately predicting the SOI, yet it is still an enormous influencing factor on climate.

Finally, your statement “2008 is still looking like maintaining temperatures that would have been a record or near-record before the big El La Niño year of 1998” is only correct if you mean record low. Hadley, NASA, UAH and RSS all show that 2008 is relatively cold, as you would expect in a strong La Nina year. See .

To argue that it should be colder, is denying that the global climate system has any inertia, which is just silly. And I am not saying that 12 months of cold weather makes a climate trend, but to claim as you do that it is relatively warm is equally misleading.

And remember, when you declare a climate change as due to a La Nina, you are only analysing the conditions relative to SOI. What about the PDOI?

I believe the data from the last 10 years adds strength to the view (as expressed by Christy, Spencer etc) that climate variability due to ocean circulation, the combined effect of ENSO and the decadal oscillations of the PDO, are dominant factors in global climate, and go a long way toward explaining global warming over the last century. This does not negate the implications of greenhouse gas warming, but it does draw into doubt the alarmist predictions made by proponents of AGW.

Philip Machanick said...

Record low? I have the HadCRUT3 numbers in front of me now. The 2007 anomaly is 0.405, higher than any year before 1998. 2008 is as yet incomplete but what we have so far is an anomaly of 0.315, again warmer than anything before 1998. The wattsupwiththat article has confused some because it compares two months in a way that the less careful reader would think it was comparing two years. Such short-term fluctuations are not part of understanding long-term trends.

The basic thing we have to consider is energy balance. If some factor (in this case CO_2) increases the effective rate of energy inflow, temperatures will increase until the outflow matches the inflow. If some of the energy goes into something that has no effect on temperature like melting ice, it will take longer to reach the new balance but we will eventually get there. Same with ENSO and PDOI. These are the things that make the graph jagged.

You claim that a model is useful if it doesn't predict. I find that odd but let's let that go. Give me an example of a model that was good fit to data 10 years ago and the same model is still a good fit when you update it to include current data.

Tobacco: I am not addressing your question of "proof" of harm caused by environmetal because it is lazy to ask me to look up something for you. I did a quick search and found dozens of papers. What you need to do is find the "ETS isn't harmful" papers and look for citations, to see if they were refuted. This isn't too hard, but time-consuming.

The issue of a vested interest is that it does not invalidate any science but it does explain why science of poor quality gets funded and given a wide airing, such as studies that bias epidemiology towards the null.

I'm curious as to what area of science you work in that has no concept of consensus. In every area of science I've worked in, there's an accepted body of theory and results that the vast majority accept and a small fringe try to refute, hoping to be the next Einstein. Lamarckian evolution is an example. There is overwhelming evidence that this is not how things work but some people persist. Who knows? They may turn up something. Epigenetic inheritance is a hint that there could be nongenetic mechanisms for evolution. But it would be silly to stop assuming the standard model when (a) the evidence for it is overwhelming and (b) the alternative theory has patchy evidence for which there is little clarity on the mechanism. You certainly would not stop all medical research that relied on the standard approach on the off-chance that Lamarck was right after all. Or would you? It seems to me that you would. Consensus is bad, not so?

If you should ever visit Brisbane, by the way, do drop in for a coffee. I appreciate the time you're taking to clarify my ideas.

Greig said...

Record low? You are correct of course, I was just being facetious. I regret writing that now. However I will take issue with your comment that 2008 will be warmer than any year prior to 1998. That is misleading. It may be correct, if you define a year Jan-Dec, but depending on where you define the 12 month boundary, I think you will find that such statements are premature. By the end of 2009, we may be seeing a new picture emerging. The next 6-12 months will be interesting. And I don’t see why the monthly data is not relevant. Sure, it is in the realm of weather rather than climate, if you are looking at relative temperature results, monthly data is still enlightening.

The basics of energy balance, we agree on. My point is that there are factors in the energy balance that have not yet been fully quantified. In my opinion, the IPCC is modeling based on assumptions which are clearly incorrect, or at least incomplete. There is insufficient qualification in the IPCC reports regarding the incomplete nature of the assumptions, and so we are starting to make some very bad policy decisions as a result.

[PM] “Give me an example of a model that was good fit to data 10 years ago and the same model is still a good fit when you update it to include current data.”

With regard to the current predictive models, we know the current data is not fitting the models very well after 1998 (including Hansen’s famous prediction!); in my opinion the CO2 correlation is clearly not sufficient. That is why I am fascinated with Roy Spencer’s work. He is coming up with ideas that make the curves fit well for the last 100 years (up to now) without including CO2 or sunspots, but simply by looking directly at the SOI and PDOI.

In my opinion, it is because there is an over-indulgence in modeling against CO2 and sunspots, because they can be reasonably predicted. Spencer cannot predict the future, because the SOI and PDOI cannot (yet) be predicted. This just doesn’t sit well with the mainstream AGW advocates and politicians. They want models that predict. Your prejudice towards predictive models is illustrative of this.

In my opinion in the real world, greenhouse forcing, ocean circulation and clouds are all factors that need to be considered to build an accurate predictive model. Of course, we only have one of those factors modeled at the moment, and that is why the models are not working. The answer is to study the factors that determine ENSO and PDO. I am arguing, there is insufficient emphasis on this, because the AGW mainstream wants to debunk anything that does not reinforce AGW. RealClimate is a forum which encourages this behavior.

Certainly consensus exists in science, but that is because we are human, and thereby engage in politics. My point is that consensus is not a part of science, and consensus does not make a scientific theory correct. I can give you dozens of examples of where consensus on a theory existed in medical science, which has later been found to be completely wrong. I agree with you that Darwinian evolutionary theory is superior to Lemarkian theory, but inmy opinion it is because it is better grounded in science. Your dismissal of Lemarkianism on the basis that it does not fit with consensus opinion, is exactly what I am saying is bad and wrong about the way the AGW issue is being treated today. Political concept of consensus is impacting normal scientific skepticism, and as scientists we should be rejecting such prejudice!

I am rarely in Brisbane, but thanks for the offer of coffee.