Lol. According to the IPCC, there is a natural forcing or forcings that would have caused temperatures to rise until 1950, then flip and cause temperatures to cool thereafter.
My question is this: What exactly is this natural forcing or forcings?
You seem to be claiming that it’s solar irradiance and vulcanism as set forth in the Hansen paper you cite. However, if one studies that paper, those forcings do not appear to match the IPCC’s claim. Among other things, it appears that nothing special happens in 1950 to cause the “flip” that I mentioned.
Thus, your claim would appear to be incorrect.
That’s completely irrelevant to my point. Again, remember the question I have been asking:
What is the natural forcing or forcings that would have caused temperatures to rise until 1950; then flip and cause temperatures to cool thereafter?
I thought it was plainly explained in the plot you linked to earlier. It shows one forcing (stratospheric aerosols) to increase from 1880 to 1930 or so, flatten out for a couple decades and then start to drop again. It also shows two other aerosol forcings decrease towards the end of the 20th century. None of the forcings are increasing in the 2nd half of the 20th century, except greenhouse gases.
You keep making this last claim despite evidence to the contrary. As I noted, what changed was
(1) The rise in solar irradiance that had occurred in the 1st half of the century stopped. (If it is difficult for you to see this on the scale of the plots from Hansen, so try this plot instead.)
(2) We had several major volcanic eruptions in the 2nd half of the twentieth century as is apparent from the negative forcings for stratospheric aerosols shown in the Hansen paper.
Taken together, the forcings due only to these natural mechanisms are predicted to have led to essentially flat or slightly cooling global temperatures in the 2nd half of the twentieth century.
(1) While some scientists may have predicted cooling (due to some combination of the natural end of the interglacial and the effects of sulfate aerosol pollutants), there was no widespread consensus on this. This is best reflected by the report from the mid 1970s by the National Academy of Sciences in which they explicitly stated that it was not yet possible to predict which effects (the cooling effects noted above or the warming effects due to greenhouse gases) would dominate.
(2) Some of the scientists (e.g., Hays et al.) have been misinterpreted (perhaps “willfully”…pun sort of intended) as predicting an ice age when in fact they made it very clear that their predictions were on a time scale of 20,000 years or more and that they were not including anthropogenic effects.
According to the chart you linked, there is little or no volcanic forcing between 1920 and 1963. I assume the downward spike at the end of this time is the Agung eruption of March 1963.
It is hard for me to see how an event in 1963 would have caused the Earth to start cooling in 1950 - some 13 years earlier.
First of all, I don’t think that good science has anything to do with consensus, and I’m surprised that you seem to think it does. There have been many times in the history of scientific progress when ‘the consensus’ was in error, and only changed very slowly, and reluctantly, over time. The fact that it did change, eventually, is A Good Thing, and demonstrates why science can progress whereas religion and faith cannot and do not. But to argue something from ‘consensus’ has never had anything to do with good science. You can either prove your hypothesis, or you can’t. Second of all, with regard to this or any similar debate, consensus tends to be in the eye of the beholder. If you want to see it, you see it, and otherwise you don’t.
I lived through the 70s and there were articles published on an almost weekly basis, everywhere from the popular press to the scientific press, expressing concern about the possibility of an impending ice age. As I recall, no-one said anything about global warming. The Cassandras were unduly alarmist and unable to prove their case then, as they are now.
Best according to whom? Best according to you because it suits your case? And in any case, I’m now confused as to the position you are advocating - are you saying that these kinds of predictions are possible, or are not? If they are possible, then you presumably disagree with the NAS report that you yourself have just introduced into the discussion. If they are not, then good, we agree that the current popular delusion about so-called global warming is exactly that. It has no more substance than the man who compares the temperature at 10 in the morning to the temperature at dawn and concludes that by the evening his home will have burnt up.
You say that “some” of the scientists have been misinterpreted. If this is true, then by implication some of them have not, and were not. And in any case, who is to say who is guilty of misinterpretation, wilful or otherwise? You write this is as if you happen to get all the facts right, but some unspecified others are misinterpreting what was said or meant, possibly wilfully. It is equally possible, and equally likely, that you are as guilty as anyone of misinterpretation.
We’ve been here before, many times. But no-one ever seems to learn. There’s a serious risk the world will run out of oil by 2000. There’s a serious risk the Millenium Bug will cause planes to fall out of the sky. There’s a serious risk that if people try to travel in trains going faster than 30 mph they will die. There’s a serious risk from Saddam’s weapons of mass destruction. There’s a serious risk that the MMR vaccine causes autism. There’s a serious risk that if you do put fluoride in water it will have long-term bad consequences (or maybe this is what happens if you don’t put it in). There’s a serious risk that witches flying on broomsticks can abduct young children (a serious concern, debated in newspapers in the 17th century). There’s a serious risk that the world will soon destroy itself because some countries have nuclear weapons (incessantly trumpeted by the ludicrous CND brigade throughout the 80s). There’s a serious risk that some new computer virus will cause widespread disruption and chaos on such-and-such a date (widely reported on an almost annual basis by both pop media and specialised press, if it’s a slow news day on the technology desk). There’s a serious risk that if we let people take fluids on planes, they can mix chemicals to make bombs (not true).
Extraordinary popular delusions and the madness of crowds. Great book. Read it and learn from it. And then add global warming to the list. The world may or may not be warming up. We don’t know. The scientific ‘evidence’ says whatever Al Gore or anyone else wants it to say. A popular movie and a has-been former VP do not good science make. There is no consensus in the science community, including the meterological community. There is no consensus because there is no conclusive evidence either way. All we have is models and speculation. It’s time to calm down and learn from the past.
Jesus Christ, brazil84. What we are talking about are the general trends over the first and second half-centuries of the 20th century. Noone said the downward trend in natural forcings started exactly in 1950. It is merely that the best estimate of trend due to purely natural forcings over the second half of the twentieth century as a whole was flat to slightly downward.
We’ve been down this road several times but let’s hoe it one time more. Yes, it is true that, technically speaking, all scientific knowledge and theories are provisional because science is inductive and can never definitively prove anything. However, if one is going to use science to inform the public and public policy (essentially, to make science “useful” to anybody), it is necessary to have institutions set up to distill the science and give the current state of scientific knowledge in a field. On an international scale, the IPCC serves this purpose for climate change science. On a national scale for all fields of science, the U.S. has the National Academy of Sciences which is specifically chartered by the federal government to inform it on scientific issues. Both of them have weighed in on climate change.
It is on summarizing the scientific knowledge that the concept of “consensus” comes up. And, yes, a consensus can be wrong and through our long history one can even find examples of it being wrong. However, when there is a strong consensus in a scientific field, it is much more likely right than wrong. Otherwise, science would not have proven to be as useful to us as it has been.
Well, while it is fun to hear your anecdotal evidence. The link that I gave you gives hard facts about actual discussions in the scientific and popular press, not one person’s impression of what they heard. If you had been reading the scientific literature, you would have known that the situation was really more complicated and, in fact, you would have known that there were competing forces that were favoring cooling and warming and not yet enough understanding to say which one would dominate.
It is best because the National Academy of Sciences is the organization chartered specifically to address these sorts of scientific questions by the federal government.
Note the date. What I introduced into the discussion was an NAS report written in the mid-1970s. Hence, it does not tell us the state of the science in 2008. It tells us the state of the science in the mid 1970s. The science has advanced since then and the same NAS that stated some 30 years ago that it was not yet possible to predict the future course of the climate has come to a very different conclusion about the state of the science in a recent joint statement with the analogous academies in 10 other major countries.
Well, yes, there were a few scientists who did push this ice age idea. That is why it is good to have organizations around like the NAS to adjudicate between different scientific opinions and say where the science as a whole stands.
Ah…more post-modernist garbage. Read the freakin’ link I gave you. It is clear that they are misinterinterpretted when George Will says “Science magazine (Dec. 10, 1976) warned about ‘extensive Northern Hemisphere glaciation’” when in fact the full quotation from the paper is:
Note the two qualifications that complete negate Will’s point!
So, your conclusion is that no dangers are real? My conclusion is that one should be skeptical of claims made in the popular press and should rely on the best science to determine what dangers are real and what are not.
What we have is scientific organizations like the IPCC and the National Academy of Sciences and professional scientific organizations all coming down on one side of the issue and a few random people (a few of them scientists, most not) spouting off about what they think they know. What it is time to do is to listen to the credible sources and ignore the ignorant or biased ones.
Lol. Look at the IPCC chart again. The trend clearly reverses itself in 1950, not 1963.
Close enough for government work, eh?
Anyway, I was wondering when you would pull out this argument.
But it only leads to more questions: First, assuming that the modelers are trying to model as accurately as possible, why would they plug in a negative natural forcing starting in 1950?
Second, how could 13 years of slop (at a minimum) in a forcing estimate result in a model or set of models that fit the temperature record so beautifully, starting in – you guessed it – 1950?
As far as I can see, there’s only one reasonable explanation: The IPCC models have been – to put it politely – tuned to match the historical records.
I think you are reading more into that chart than you are able to. Note that the blue region is wide for a reason…It represents a whole ensemble of simulations. (I think there also might have been some smoothing…or connecting the dots…involved in producing that plot from the original data.) It is better to look directly at a graph showing the individual simulations. To do that, look at Figure 9.5 (p. 684) in this large PDF file of Chapter 9 of the IPCC report. It actually looks like the simulations show the temperature pretty flat until the early 60s when that first eruption kicks in.
What they plugged in was the actual historical reconstructions that we have for the various forcings.
The better explanation is that you simply don’t know what you are talking about.
I looked at the graph and zoomed in very closely. It’s impossible to make out any of the individual simulations. What appears to be an average line starts dropping a good five years before 1963, however.
In that case, why would non-anthropogenic forcing start cooling the world in 1950? (Or 1957?)
Lol. Funny that you have no answer for my question, then.
Anyway, the IPCC has all but admitted that some or all of the models it relies on have had fudge factors thrown in:
You are micro-analyzing a system that has noise…i.e., natural variations…in it. So, there are small ups and downs even without any forcing. I don’t think the downturn is very significant until the eruption.
This is a whole different thing that we have already discussed before. Yes, it is necessary to do a little bit of tuning or “flux adjustment” (either explicit or implicit) in order to have the models not exhibit drift when there is no forcing. This is not surprising because any effect (such as clouds) that is not gotten exactly correct down to the level of a fraction of a W/m2 (when the total inputs and outputs are several hundred W/m2) would lead to such drift.
However, this is not the same as tuning to make the models reproduce the historical temperature record. As I have noted before, if this could in fact be done, theh there are models out there in the public domain that any “skeptical scientist” could tune so that they reproduced the historical temperature record just with natural forcings and no anthropogenic forcings. Strange that this hasn’t happened, eh?
By the way, here is an article in today’s New York Times reminding us that global warming is not the only potential problem associated with the increase of CO2 in the atmosphere.
Again, this is the “close enough for government work” argument. The problem is that there is visible slop in one part of the simulations, and yet a beautiful fit in the output. Not only that, but there are two noticeable dips in the instrumental record around 1950 and again around 1957. What a wonderful coincidence that the models start dipping at those times!
And yet the models still exhibit noticeable drift when there is no forcing. And the drift happens to result in a beautiful fit to the instrumental record.
I’m not sure what they mean by “realistic state.” Anyway, the IPCC hints that the models are tuned by use of radiative parameters. Tuned to what? A “realistic state,” I suppse. I wonder what that means . . . .
Anyway, if we know that the models have been fudged in one respect, it doesn’t inspire a lot of confidence.
I don’t know if it’s happened or not. Are the models that the IPCC makes use of in the public domain? Has the source code been released?
So you don’t know whether the plot has enough resolution to say whether the drop occurs in 1950 or 1963. Or whether the magnitude of the drop is statistically significant or just noise. Why do you keep using it as basis of your argument when you don’t even know which of the features are real?
