Reuters saw documents saying something like that:
Drafts seen by Reuters of the study by the U.N. panel of experts, due to be published next month, say it is at least 95 percent likely that human activities - chiefly the burning of fossil fuels - are the main cause of warming since the 1950s.This figure was discussed by Watts Up With That and The Hockey Schtick (via Climate Depot).
That is up from at least 90 percent in the last report in 2007, 66 percent in 2001, and just over 50 in 1995, steadily squeezing out the arguments by a small minority of scientists that natural variations in the climate might be to blame.
I am stunned how underwhelming such statements are and my being stunned has several levels.
What do I mean?
- First of all, the figure 95% isn't really calculated in any way. It's literally pulled out of the air. The gullible audience of the IPCC is supposed to believe that the IPCC members are shamans with supernatural skills and if they vote about and approve a figure they randomly invent, it's a deep and accurate truth one should worship. But there are no shamans in the real world and most of the IPCC members not only fail to be shamans but they also fail to be competent scientists.
- Even if the figure 95% were credible, it's just painfully low. I will discuss some analogies in high-energy physics below.
- Even if the figure 95% were credible, calculated, and replaced by a much higher figure, the statement we have "learned" is completely unspectacular, pretty much inconsequential, and unworthy of spending another dollar. Yet, some people seem to think that this unspectacular statement directly implies that we should throw hundreds of billions of dollars out of the window.
First, the figure 95% isn't being calculated from anything.
In particle physics, statements or findings that are "95% certain" are usually referred to as "2-sigma deviations" from the null hypothesis. The numbers 95% and 2 may be translated to each other using the precise maths of the normal distribution (or a more accurate distribution, whenever it is relevant).
The number of standard deviations, 2, is calculated from the experimental data in a straightforward fashion. There's a clearly defined calculation that may be done by a computer. You insert the theoretical predictions from the null hypothesis, the measured data, and the program may calculated how much the observed values deviates from the predicted value and how likely it is for such a large or larger deviation to occur by chance.
The climate scientists and green activists in the IPCC act like shamans who vote about a figure. You could offer an excuse. The climate is a complex system and the conclusions are being based not on one well-defined measurement but on numerous branches of the empirical data. Each branch gives you some "feeling" and you sort of accumulate these feelings and guess the final answers and the numerical value of the confidence level, too. A more precise accumulation of the "feeling" is obtained if many people smoke together – this is called the "consensus science".
However, you should understand that this is no real excuse. Instead, it is a confirmation that the final figure simply cannot be taken seriously. If you don't have any single experiment or a single collection of measurements that is strong enough to nontrivially support your hypothesis, then it's too bad.
Of course that you may try to combine several not quite convincing datasets in order to increase the confidence level above the confidence level of each individual dataset. But when you do so, you are at risk that the datasets aren't really quite independent (the signs of a higher temperature in regions and across the globe surely fail to be independent as well) so the increased confidence level calculated from the assumption of their independence may be a heavy overestimate. Moreover, you can be reasonably accused of cherry-picking the datasets that agree with your predetermined conclusions – and from the censorship of the datasets that don't support your "cause". Of course that I think that both accusations are true descriptions of the IPCC's work.
Also, the shamans boast that their guessed "certainty" has grown from 1.8 sigma to 2.0 sigma from 2007 when the previous IPCC report was released. Just six years and they were able to increase their guessed signal from 1.8 sigma to 2.0 sigma. It's so impressive! ;-)
So the numerical value isn't a result of science. It's a result of shamanism. But even if the IPCC were able to calculate the figure 95% using a legitimate scientific procedure, there's the second problem:
The confidence level 95% is just incredibly low.
As I said, the 95% confidence level is known as the 2-sigma confidence in hard sciences such as particle physics. Particle physics experiments have brought us hundreds of 2-sigma excesses – and lots of much larger (more confident) excesses – and a vast majority of them turned out to be flukes. When more data were accumulated, these excesses just went away. Such things inevitably occur all the time.
Because people keep on looking for new effects, they inevitably encounter flukes that look like a new effect but the effect actually doesn't exist. A priori, a new effect is always a pretty unlikely thing so if you look at the history of particle physics, most of the 2-sigma deviations were really flukes – results of coincidences that shouldn't have been paid any attention to.
Particle physicists start to seriously look at deviations when they reach something like the 3-sigma level or 99.7%. The conventional threshold of discovery is 5 sigmas which means approximately 99.9999% certainty.
But imagine that in the 6th IPCC report, the shamans replace their guesswork by a calculation of the confidence level based on some empirical data; and that the confidence level will increase to 99.9999% so that it becomes convincing. There will still be one problem:
The claim that we 95% believe to be right is completely innocent, unspectacular, and mostly inconsequential.
To see what I mean, look at the proposition that is known with the not-really-calculated 95% not-really-certainty:
Human activities - chiefly the burning of fossil fuels - are the main cause of warming since the 1950s.What does it exactly mean? Since the 1950s, i.e. in the last 60 years, the 5-year-averaged temperatures jumped by something like 0.5 °C. The "holy" proposition above doesn't even say that the human activities are responsible for more than one-half of this figure i.e. for more than 0.25 °C – which is a completely negligible and practically undetectable temperature change, anyway.
Instead, the vague proposition above only says that the human activities are the "main cause" which probably means that the magnitude of the contribution from human activities is the largest ones, exceeding every other single contribution (it's being implicitly assumed in the proposition above that the contributions may be "naturally" and "objectively" separated to piles, which is also nonsense, but let's assume that they can).
But if this is the right interpretation, the human contributions could have been just 0.1 °C (perhaps with the minus sign) and its absolute value was just larger than the absolute value of the ten subleading sub-0.1 °C contributions from natural processes. All of them happened to add up to 0.5 °C.
So the proposition that we "know" with the 95% certainty (where the figure 95% was guessed by shamans) is compatible with the assumption that the human activities changed the temperature by a practically undetectable amount in the last 60 years – in fact, this interpretation is still likely if we assume the basic quoted proposition to be right.
Just try to combine all the vices in your mind: the confidence level is a guesswork, it is extremely low, and the "known" proposition doesn't really imply anything you could possibly care about.
How could a rational person spend a single dollar on a campaign that is primarily motivated by the proposition, one that suffers from the three basic lethal diseases? The answer is, of course, that no rational person is paying any real attention to this campaign.
Let me offer you a particle physics counterpart of the situation.
In one of the LHC searches for the microscopic black holes, someone finds a small bump that may be interpreted as the production of several small black holes by the LHC. He can't really calculate that it is a 2-sigma excess because no well-defined channel produces such an excess. But he combines his and his colleagues' feeling about many graphs and they say that in some combination penetrating all of their research, they see an excess that is comparable to a 2-sigma excess so that they are 95% certain that the LHC has produced a small black hole.
However, the hypothesis that the black hole of this mass is produced doesn't really agree with all the other data – which seem to falsify it. So they invent that the black holes produced by the LHC may be non-standard. In fact, they don't Hawking-evaporate. And because they don't evaporate, they may be produced in the rest frame and devour the Earth.
Fine, so these scientists and their friends urge the Earth to stop the LHC, X-ray machines, and every other device in the world where particles are accelerated to higher energies because there's a risk that the destructive black hole they have discovered with 95% certainty will destroy life on Earth along with the planet itself. This scenario doesn't really follow from the proposition they have "not quite proven" to be 95% certain but a danger doesn't follow from the proposition in the IPCC case, either. Hundreds of billions of dollars have to be paid every year to fight against the danger pointed out by the brave 2-sigma particle physicists.
Do you see how crazy it is? It sounds as a joke, a really stupid one. This would not be remotely possible in particle physics. A psychiatrist would be immediately ordered for the particle physics experimenters who would offer this story. However, the IPCC is doing the exactly isomorphic thing. No one has isolated them in an asylum yet and there even exist people who take this stuff seriously.
We don't live in a scientific world.
Off-topic: ghettos in the U.S.
Below is a picture of Greater Boston; see the background map to compare (switch).
CTRL/click above to open a zoomed in image in a new tab.
Boston and Cambridge are so multi-culti and they're embedded in the would-be uniform American melting pot. Still, they are composed of ghettos. One pixel is one person from the 2010 census. Can you find the Chinatown? Yup, it's the red place in the vertical center. Can you guess where the blacks and hispanics (green and yellow) live relatively to the Chinatown? Yes, it's in the South Boston.
Get to this zoomable map that can show you the whole U.S. and every town and region in it. Via Pig.