I believe the idea that galactic cosmic rays (GCR) play a role for the present global warming is unlikely to fade soon, despite a growing number of scientific arguments that normally would falsify a hypothesis and lay it dead (see links here and here). Despite all the arguments against the role of GCR, there was a solicited talk about ‘cosmoclimatology’ at the European Meteorological Society’s (EMS) annual meeting in Toulouse. Henrik Svensmark is further invited by the Norwegian Academy of Science and Letters (NASL) to provide an introduction to their seminar on climate. So why is the GCR-hypothesis still perceived as an interesting explanation?
My impression from the solicited talk, is that the confidence in the GCR hypothesis now rests on two points that were made explicit in the presentation, and that we have not adequately addressed here. So, here they are:
Point I: When I asked Svensmark why he presented a curve describing low cloud-cover from the ISCCP – used for correlation study with GCR (link) – that differed from the curves presented at the ISCCP web site (link), he informed me that he used a corrected version that has been published. Nevertheless, the ‘correction’ of the curve is controversial, and the ISCCP team is clearly not convinced, despite the likelihood of instrumental degradation.
Good practice would then be to present all the curves that cannot be ruled out because of errors. When asked why he didn’t present the other cures too, he said that he only wanted to show the one curve. Not a very convincing answer, and not very reassuring.
Point II involves a ‘remarkable’ correlation, meant to demonstrate a link between high GCR flux and cold conditions. This analysis is based on a comparison between band-pass filtered ice-rafted debris from iceberg drifts (Bond, 2001) and Carbon-14 (a cosmogenic isotope) over the last 12,000 years (e.g. after the most recent ice age).
The relationship between temperature and drifting icebergs, however, is complicated and not so straight forward. Icebergs are formed when chunks of ice break off glaciers and icesheets – a process known as ‘calving’.
On the one hand, icesheets and glaciers grow when the accumulation of precipitation at below freezing temperatures (snow) exceeds the summertime melting. Very low temperatures, tend to be associated with low precipitation, however. One the other hand, iceberg calving does not require very low temperatures (as long as the ice is present), but is favoured by reduced friction at the base of ice caps, resulting in a faster flow towards the sea. Melt water can lubricate the ice sheets and hence affect the ice flow.
Once the icesheets have calved and produced icebergs, they will drift according to the winds and ocean currents. The most influential ocean currents for iceberg drift in the North Atlantic include the East Greenland Current EGC), which follows the east coast of Greenland and flows from northeast to southwest, the West Greenland current (WGC) into the Labrador Sea, and the Labrador current (LC), a coastal current following along the perimeter of the Labrador sea basin in an anti-clockwise fashion.
Many of the cores used to study the ice-rafted debris were from locations away from these currents. It is not clear whether anomalous cold conditions produced more southerly winds and ocean currents. However, many of the core locations are associated with a surface flow from the south in the present climate, so it is possible that the icebergs transported by the EGC, WGC, and LC end up in the North Atlantic current. One explanation is that the icebergs got caught in the warm currents from the south, and melted on their way north, but that does not necessary imply cold conditions in that region, as these warm ocean currents provide a heat transport and the melting of icebergs suggest higher temperatures.
Cold conditions favour the formation of sea-ice, which have very different characteristics to icebergs. Sea-ice forms when the sea surface freezes, and can affect the ocean circulation through their effect on salinity. However, sea-ice does not create debris of rocks and minerals, as the icebergs do when the bottom of the sliding icesheets scrape the rocks.
It is plausible that very cold conditions can produce thick sea-ice that will lock icebergs in place near their sources in the Labrador sea and along the east coast of Greenland, but seasonal variations in the sea-ice may also imply open water in the summer. Nevertheless, very cold conditions may not necessarily favour the production of icebergs, as freezing temperatures will prevent the formation of melt water acting as lubrication and the accumulation of ice is expected to be less due to lower precipitation.
In summary, the ‘remarkable’ correlation does not seem to support the hypothesis that high flux of GCR produces a very cold climate. The question is rather whether the ocean and atmospheric circulation were influenced by the level of solar activity and associated changes in the total solar irradiation (TSI) – without involving GCR. After all, GCR is affected by the level of solar activity through its influence of the inter-planetary magnetic field, and anti-correlated with the sunspots.
When taken in the context of the global warming, there are other problematic issues such as the lack of trend in GCR (here and here), stronger warming during nighttime than daytime, large unknowns regarding the physical mechanisms involved in the growth of ultra-small molecule clusters to much larger cloud condensation nuclei (here and here), and questionable data handling and statistical analysis (here). In addition, it is difficult to statistically distinguish between the apparent response to solar forcing in the observations and GCM which do not take GCRs into account (link to a recent paper by Gavin and myself), implying that GCRs are not needed to explain past global temperature trends.
So what makes the GCR-hypothesis so convincing that warrants a solicited talk at the EMS annual meeting and an invited presentation at the NASL? Is the support based on the attention in media, or does it have a scientific basis?
I want a response from the community still supporting the GCR hypothesis, explaining why they find it convincing after all these misgivings. The spirit of science is about discussing different ideas and challenge unconvincing points of view. So far, I feel that many of these issues have gone unheeded outside the climate research community. Perhaps an improved dialogue between various research communities can help resolving these issues – the counter-arguments and GCR hypothesis represent a paradox that should be sorted out if the science is to progress. Either the supporters of the GCR hypothesis should convincingly explain why these misgivings are unfounded or irrelevant, or the GCR hypothesis should be buried. However, I feel that there is a lack of dialogue and willingness to listen, so I think that progress is not likely to happen regarding a commonly accepted solution on the GCR hypothesis.
Update: According to a recent (October 16) news relsease from the International Ice Charting Working Group (IICWG), over 1,200 icebergs drifted into the trans-Atlantic shipping lanes in 2009, making the iceberg season in the North Atlantic the eleventh most severe since the tragic loss of the RMS Titanic in 1912.
P.S. So far in 2009, three articles have been published in the arXhive on GCR and clouds (here, here, here). It is possible that such articles are more accessible to communities other than climate research, and hence enhances the awareness about the controversy surrounding the GCR-hypothesis.
Richard Pauli,
The question of whether GCR influence climate is an interesting and valid area of inquiry. If it were not for the unfortunate fact that our energy infrastructure is carbon based, these efforts would chug along slowly attracting only limited interest and funding. The ABC interests pour gasoline and liquid oxygen on the smouldering ember–which still doesn’t catch fire, because there just isn’t that big an effect.
#77 Thomas – it’s not about climate change true or false, right or wrong, it’s about appetite for risk. Once again I’ll punt greg craven’s approach. I think his analysis is brilliant and not too late I hope. Sure, continue debating the nitty gritty of the science, but the scientifically illiterate that post here would be best served by reading Greg’s book first – even before they tried to learn some science. In fact they will learn what science is about by an honest reading of the book.
“What does the motivation of the deniers matter? Just prove them wrong and leave it at that.”
Problem: they get to decide when they’ve been proven wrong.
This is not easy.
So you have to nail them down on what they consider proof.
Heck, they’re still saying “CO2 ***lags*** climate change!” and “Computer models aren’t Science!”.
Until we have control over time (and a spare earth or three), if we try to prove them wrong before finding out what would prove them wrong, they’ll just say “that’s not proof. GET ME PROOF!!!!”.
Mr Henderson asks:”What does the motivation of the deniers matter? Just prove them wrong and leave it at that.”
You can’t reason someone out of a position that they did not reason themselves into. Psychology is important – why does someone deny reality?
79 Mark,
I’m sure I’m missing something humorous there but I can’t see it.
piston aircraft burn a lot of hydrocarbon fuel.
96,103,105,106:
I think the motivations of the denialists do matter. In my example (btw I have no problem with AGW theory, its just radiative transfer complicated by CFD & weather processes) the second law of thermo principle is falsifiable, the religious based one not so much -especially as we don’t have a spare planet to demonstrate what happens with/without GHGes.
But, if you can expose the reason why ABC is nonnegitiable then you have to chance to do two things:
(1) Maybe, the denialist will realize he is starting from a false presense, and come around.
or
(2) His credibilty will be taken down several notches.
The reason this matters, is proving them wrong with detailed analysis/argumentation is beyond the capability of the large bulk of the target audience, they simply cannot judge based upon the quality of the science. Your odds of winning a popular debate with scientific truth alone is small.
Is the continued interest perhaps a somewhat benign version of the manufactured controversy that newspapers were/are accused of?
Making sure there is some alternative viewpoint considered.
In order that an alternative idea not appear to be “shut out” some accommodation is being made???
Hi,
I have a question that keeps bugging me. I often read that the average global temp has risen by 0.6 degrees C since 1850. So, that makes 0.04 C/decade or 0.004 C/year on average. My question is how were these temperatures measured before modern digital equipment? Surely prior to the 1960 or 70’s the accuracy of the equipment used would have been at least +/- 0.1 C for each reading? Thanks in advance.
#104 Mark
I agree
On one site a guy asked for one example that shows Co2 is a greenhouse gas and he would change his mind. I sent him to a youtube item. And he said but that is not the same concentration that’s in the atmosphere, show me one example of temperature rising with the levels of Co2 in our atmosphere. I said the earth atmosphere has that, and temperature is rising… and he said that doesn’t prove anything…
If an individual is sold on a believe (psychology is important) then you really do need to address the premise of that psychology to unravel the twisted mechanism that leads one astray. It seems moving the goal posts on a question is always valid in the mind of some.
I think that by and large, the scientists active in the field are sincere in what they believe, and that counts for contrarian scientists as well. What may play a role for some of them is what I call professional deformation (as BPL also noted in comment 2): Everybody has a tendency to think along familiar lines. Moreover, once you have made a name for yourself in proposing a certain theory, it’s hard to step away from it. There’s a certain attraction in being the underdog, which, in extreme cases, leads some to think of themselves as (supporting) the new Galileo. And, as I pointed out in a previous comment, the correlations (if taken at face value) are seen by many as a sign that there is something to it, though we don’t know what and how much yet.
The ABC process (anything but CO2) is probably more important for the non-scientific followers of contrarian hypotheses, but also in that segment there are a good few who are sincerely confused of where the bulk of evidence is pointing towards.
“My question is how were these temperatures measured before modern digital equipment?”
http://inventors.about.com/library/inventors/blthermometer.htm
“Galileo Galilei invented a rudimentary water thermometer in 1593 which, for the first time, allowed temperature variations to be measured. In 1714, Gabriel Fahrenheit invented the first mercury thermometer, the modern thermometer.”
Why do you need a digital thermometer to take the temperature?
“(btw I have no problem with AGW theory, its just radiative transfer complicated by CFD & weather processes) ”
btw, if that’s all the problem you have, then forget the complications.
You’d have to have a very unlikely amelioration to get all these complications wrong so that
a) it looks like you’re boned on a business as usual scenario
b) but they will come back and make it all A-Ok.
How likely is that?
In this case, the uncertainties mean that you’re as likely to underestimate the problem as overestimate it.
MacDoc, 109, you are so right!
I think this is exactly it! And I am 100% one of these people. I don’t like reading in the papers the same AGW theorie again and again…even if it is the most likely. The problem is: if this theory is correct, it means urgent action. For urgent action you need a consensus. And then it becomes political. And then you cannot see anything else in the newspapers. But we (at least I) NEED to see the other points of view. We need to breathe. It is as simple as that.
To make a simple comparison, I don’t like when too many good things are told about one single person, because I believe nobody is a angel. And it leads to the cult of personality.
The same thing for climate science. I don’t like this consensus. It is a “cult of a science”. We NEED contradiction! Just to breathe.
Jake,
Even with big error bars on an individual measurement, the more readings you have, the more tightly you can pin down the average. See the definition of “standard deviation” in a statistics text.
#104 Mark “So you have to nail them down on what they consider proof.”
In a sense this is Greg Craven’s approach. You, as skeptic or warmer are challenged to set up your own criteria for what will convince you that AGW is happening or not happening, respectively. You are also challenged to set up your own “credibility spectrum”, from more credible to less credible, and fill in the various sources of information (for AGW real or not) on that spectrum – sources such as the IPCC, professional scientific societies, business groups, the military, blogs, individuals, petitions, etc. Then you decide, using your own crediblity spectrum, whether to bet “take no significant action now” (because future catastrophic climate change if we don’t take action now is an unreasonable probability) or “take significant action now” (because if we continue CO2 emissions future catastrophic climate change is a reasonable probability). This circumvents the need to even consider the “odds of winning a popular debate with scientific truth alone” (Thomas #108). Time is short, governments are back-tracking as Copenhagen approaches and it’s looking like the winning bet will be “take no significant action now”. And by that I mean that CDM has been a failure and no sense that anything more significant will replace it. Commitment must be to a level of CO2, not some possible future temperature rise – Jim Hansen says 350ppm max, that means carbon sequestration to remove CO2. I’m voting 350 and I have applied Greg’s process to reach that conclusion – anyone else here prepared to show their hand? No use winning the debate and losing the battle.
Mark #95
“… the height of contrail formation was calculated on 1950’s planes …”
Indeed. The height of contrail formation was crucial to the successful recording of the attempt at the World Air Speed record by Peter Twiss in the Fairey Delta 2 in 1956. Twiss’s account in his book ‘Faster than the Sun’ makes a fascinating read.
Jake, you are confusing “digital” with “accurate”. By the mid 1800s, 0.1 degree accuracy was certainly obtainable with good laboratory equipment. Coverage was a more serious issue. However, there are independent lines of evidence (e.g. phenological studies, melting of glaciers and ice caps, etc.) that support a rise of about that magnitude.
107 Eli,
And jets don’t?
BTW, “prima facie” means, roughly, “at first glance” or “on the face of it.” It doesn’t imply certainty or obvious truth. A “prima facie” case is simply one that’s worth looking into.
I belive Svensmark is looking into it.
Jeffrey, but at first glance, or on the face of it, GCRs aren’t causing any significant warming.
So, again, why the continued interest?
“But we (at least I) NEED to see the other points of view. We need to breathe. It is as simple as that.”
Do you need to see the other points of view on ritual mutilation of women? Do you need to see the other points of view on murder?
Do you need to see the other points of view of the earth’s shape?
a) there are some things that are just verboten by any civilised society that wants to continue to exist
b) there are some things where the other points of view are so bad, they’re not even wrong
“So, again, why the continued interest?”
I suspect it’s a hobbyhorse idea for him. Like something out of Tristam Shandy.
He’s imagining the same kind of mechanism for GCRs as do the people who contrive perpetual motion machines or who can fly in their dreams.
There’s a mocking poster which shows a correlation between global warming and the number of pirates. Since there’s a demonstrable mechanism involved with GHGs and warming, the poster is simply a dumb joke. However, it’s apt for Svensmark. He can see all manner of correlations, but there’s nothing that can parlay the tiny energy behind GCRs into global warming.
re #121/123
I think these statements are true:
1. Yes it’s worth looking into the CRF-cloud nucleation-climate hypothesis
2. No there isn’t any compelling evidence for a CRF climate relationship.
3. There is very little doubt that there has been negligible CRF contribution to the very marked warming of the last 30-odd years.
4. Yes there is some somewhat tantalizing evidence that there might be a CRF-cloud effect but this is so far based on small bits of observation of apparent correlation (e.g. solar cycle 22 with the ISCCP-IR product), which didn’t hold up to subsequent observations (e.g. CRF – cloudiness become discorrelated through cycle 23 and in any case the correlations are poorer with the more reliable ISCCP-IR/vis product), and further a significant body of work now indicates that the apparent CRF-cloud correlations through cycle 22 are actually correlated with the irradiance (TSI) component of the solar cycle (rather than the CRF component). There are also some tantalizing possible effects observed in some rare Forbush events, but the reproducibility is so far questionable and causality not established.
5. There is no compelling evidence whatsoever for any CRF contribution to earth surface temperature change throughout the last 1000 years, the climate variation of which can be understood pretty well in terms of known internal and external forcings.
6. There is no compelling evidence whatsoever for a CRF-climate link throughout the entire Phanerozoic period. In fact much of the climate variation during these vast periods (500 MYA) can be understood in terms of greenhouse gas levels, the steady increase in the solar constant, continental land mass rearrangements, plant evolution, and various internal and extraterrestrial catastrophes (tectonic events and impacts)….
7. If we’re serious about understanding the contributions to very marked 20th century and contemporary warming, and the likely consequences of continued massive enhancement of atmospheric greenhouse gas levels, the CRF hypothesis is of little interest or relevance.
And the key point for this general discussion:
7. A very small number of CRF advocates entirely ignore or misrepresent the rather abundant science on this subject and present a false view of the science that elevates a potential phenomenon with a marginal evidence base as if it were a well established contribution to climate variation including mid-late 20th century and contemporary warming. This is done not only under the rather understandable psychology in which scientists may make strong personal investment in poorly evidenced hypotheses, but in this cases encompasses various degrees of dishonesty (i.e. it’s difficult to conclude that the scientific misrepresentations are not made knowingly).
124 Jeffrey,
I assume you mean Church Of The Flying Spaghetti Monster?
“There’s a mocking poster which shows a correlation between global warming and the number of pirates. Since there’s a demonstrable mechanism involved with GHGs and warming, the poster is simply a dumb joke.”
ARE YOU MOCKING HIS NOODLY APPENDAGE????
Well, next time you open a can of chopped tomatoes and it squirts over the floor, you will know His Wrath at last!
Bart #112
I’ve read your fine piece about aerosols and climate here on Real climate (15 april 2009). So I thought I’d take the opportunity to ask if, in your opinion, Svensmarks newest paper adds any relevant knowledge in that context? If the answer is no, then my next question is if there’s anything, whatsoever, of interest in that paper.
Chris #125
That was a pretty good summary (though I wouldn’t agree on all points)!
As you’ve maybe noticed I’m new at this blog. I have to say that I’m quite surprised by the language used here! This guy Mark equals AGW-skepticism with murder and mutilation of woman. Is that for real?
[Response: Don’t be ridiculous. You made a general philosophical point in support of your anti-AGW position which Mark showed (reducto ad absurdum) was bogus. It is a comment about your logic, not your science (such as it is). No more on this particular red herring please. – gavin]
Of course I can skip every post by Mark and read only those with some quality, like Chris, Bart V etc. Not a big deal, but I’m still confused. What are the moderators doing? Isn’t this supposed to be site for scientific discussions?
Some relevance to this discussion in a recent paper in atmospheric chemistry and discussions:
“Atmospheric data over a solar cycle: no connection between galactic cosmic rays”
and new particle formation, see:
http://www.atmos-chem-phys-discuss.net/9/21525/2009/acpd-9-21525-2009.pdf
The open interactive discussion will probably be both lively and interesting…
” Of course I can skip every post by Mark and read only those with some quality, like Chris, Bart V etc. Not a big deal, but I’m still confused.”
Now how does this square with his earlier statement:
“But we (at least I) NEED to see the other points of view. We need to breathe. It is as simple as that.”
Are not posts by mark not another point of view? Has Bengt stopped breathing, as simple as that?
PS this is one reason to take things WAAAAAY over the line. Bengt has decided after all, there ARE things that aren’t worth considering.
Like the demands to see others POV even if they are unscientific or even anti-scientific.
#59 Eli,
Yes, correct, Svensmark has been tossed out – although he is a coauthor of
http://www.atmos-chem-phys-discuss.net/9/18235/2009/acpd-9-18235-2009.pdf
Also, a number of authors of the paper referred to by Theo (#130) are involved in CLOUD.
Has any plausible reason been given by Svensmark for why we’re looking at low level clouds, and not also high altitude clouds?
In my comment above, “atmospheric chemistry and discussions” should have read “atmospheric chemistry and _physics_ discussions”, of course…
Thanks Adder (post #132)…that’s encouraging.
It seems like there are some serious scientists involved in the CLOUD experiments (e.g. Lockwood; Harrison), and good for whoever it was that brought together this expertise. My initial impression was that a substantial amount of cash (my tax Euros!) had been winkled out of the EU 7th Framework Programme under slightly dubious pretences, but I’m much more confident that the data will be assessed and interpreted properly now.
I still have my doubts whether the experiments will have very much to say about CRF-cloud responses in the real (outdoors!) world, but I have no problem in being proven wrong.
… and perhaps it doesn’t matter so much that Dr. Kirkby seems to have a fundamental problem with [edit] depiction of the background climatology that bears on this subject….
Jake (110) — Lots of thermometers were used and statistics applied to the resulting numbers. More gives a better estimate than just a few.
The clear difference between Svensmark, Lindzen et al. and the dominant CO_2 AGW theory is that the CO_2 theory has been thoroughly tested after its initial tenuous start in the 19th century before we had quantum physics and large-scale computers on which to model planet-scale physical systems. If you look at the timeline of the establishment of the CO_2 theory, it took the best part of 150 years to move from speculation to an established theory. It has been thoroughly tested in numerous models and thousands of publications. The GCR hypothesis will most likely end up like any other hypothesis in science that goes nowhere because the evidence doesn’t support it. The only reason Svensmark is attracting more attention than any other crackpot alternative to a mainstream theory is he offers hope to those who oppose change. If you really want an extreme case, look no further than Bjorn Lomborg (remember him?) who had published exactly 1 academic paper in a totally unrelated field (political science) and somehow was considered sufficiently expert in an extremely complex field to debunk the whole thing. When people are keen to grasp at a straw, they don’t check how well the straw has been made or who made it.
#124, -6 & -7–There may be an “inadvertent experiment” going on. If recent news stories from the Indian Ocean are accurate, the number of pirates has recently shown an uptick above the 17 shown on the classic “spaghetti” graph. This should induce global cooling if sustained, no?
(Does anybody have info on the “pirate/climate equilibrium equation?” There has to be a way to quantify pirate sensitivity.)
Umm, I probably don’t really need to clarify this, but I meant sensitivity of climate to the pirate forcing, not sensitivity of the pirates themselves. (That is of course still awaiting reliable measurement, but is certainly negligible for most boundary conditions.)
Why the continuing interest in a natural explanation for climate change? Because that is the conventional wisdom which must be disproved, in accord with the scientific method, before the challenging hypothesis can authoritatively replace it. The more interesting question is why the resistance by AGW adherents? Perhaps because the challenger has precociously inverted the burden of proof, proclaiming victory by consensus and demanding disproof of the challenge? The IPCC’s admission of primitive understanding of cloud behaviour is evidence enough of a premature declaration of settled AGW science.
110 Jake
Hi Jake. I struggle with the same issue (can we really know the global temperature has risen .6 degrees using what we have for temperature records from 1850 until now). I’ve had only one course in statistics in college and unless I make the effort to get a deeper understanding of the power of using statistical analysis to come to this conclusion, I will have to remain a bystander watching the discussion play out.
I have been developing software for the past 20 years and have a hard time accepting that use of the tools of the statistician can overcome gigo (Garbage in Garbage out) but that doesn’t mean that it isn’t so (not meaning that the data is garbage in general but for the purpose of drawing conclusions to a tenth of a degree …). I think there are a lot of us in this boat. We’re not part of the fossil fuel industry (I’m working in the clinical trials industry – doing records management, not statistical analysis), and it’s not a matter of having some internal bias one way or the other. It’s just we don’t have the understanding of the power that statistical tools have so can’t make the leap to fully trust them and the conclusions drawn that rely on them.
I apologize if I’ve drawn you into my boat incorrectly. You may be a master of statistics for all I know but your post kind of hit the nail on the head for me, drawing out a rare post from me. I’ve made a few posts here and did receive very helpful info from the folks at this site (I read here almost daily). I don’t feel too comfortable posting much though because expressing any doubt as in the above, can draw some pretty ugly replies (which have had what is probably the desired result, I don’t post much). I had thought this was just tolerated by RealClimate as normal part of the blogosphere but the inline note from Gavin in post 129 suggests that it may be advocated.
Good luck to us both in our search for the truth.
Might find this interesting… There are a lot of documents like this out there that kind of give a feel for how some of the early data was collected.
http://climate.umn.edu/pdf/Fisk_thesis.pdf
Tad
“I have been developing software for the past 20 years and have a hard time accepting that use of the tools of the statistician can overcome gigo (Garbage in Garbage out)”
There’s no need.
DON’T PUT GARBAGE IN.
GIGO is then not a problem.
Why do people always assume that GIGO is impossible to avoid? Is it because those who deny AGW have nothing but garbage to put in? Maybe you should consider whether your attitude is a garbage out problem…
“Because that is the conventional wisdom which must be disproved, in accord with the scientific method, before the challenging hypothesis can authoritatively replace it.”
Here’s a Garbage In problem.
Why must conventional wisdom be disproved?
What if conventional wisdom is in this case correct?
And surely if you MUST disprove conventional wisdom, it would behoove you to find something BETTER at explaining the real world than the conventional wisdom you wish to replace.
After all, you wouldn’t try to displace the conventional wisdom that the sun is the source of all our heat with a theory that it is actually The Interstellar Spaghetti Monster, would you?
Well, maybe YOU would…
Jake, Tad,
If you’re seriously interested: try reading P. Brohan et al., “Uncertainty estimates in regional and global observed temperature changes: A new data set from 1850”, Journal of Geophysical Research 111 (June 24, 2006): D12106. Even if your grasp of statistics is as shaky as mine, you should be able to get a rough idea of how it’s done.
Kevin, #138.
However, you notice that the Som ali Pirates only recently came into mainstream press. Around 2000-2002, IIRC.
And as any denialist will tell you, the temperatures have been flat since then…
Proof Positive of the Organza Effect!
Bengt A (128),
I guess you’re referring to his paper on Forbush decreases (FD)? I have only skimmed it, but it is contradicted by other studies where no link with FD’s was found. A 7 day lag time as Svensmark proposed/found seems rather long to me; I wouldn’t expect a decrease in nucleation to affect CWC 7 days later. At first sight, it looks like a valuable contribution to the literature, as a polite reviewer would call it, but it doesn’t change the broad validity of Chris’s summary (125), nor would I have changed my post back in April because of it.
Tharanga (133), you asked “Has any plausible reason been given by Svensmark for why we’re looking at low level clouds, and not also high altitude clouds?”
See e.g. https://www.realclimate.org/index.php/archives/2009/04/aerosol-effects-and-climate-part-ii-the-role-of-nucleation-and-cosmic-rays/:
Based on his model for ion induced nucleation, Yu found that at low altitude, the number of particles produced is most sensitive to changes in cosmic ray intensity. At first sight, this may be a surprising result in light of the increasing cosmic ray intensity with increasing altitude. The reason is that high aloft, the limiting factor for particle formation is the availability of sulfuric acid rather than ions. Above a certain GCR intensity, increasing ionization further could even lead to a decrease in ion induced nucleation, because the lifetime of ion clusters is reduced (due to increased recombination of positive and negative ions). In contrast, at low altitude particle formation may be limited by the ionization rate (under certain circumstances), and an increase in ionization leads to an increase in nucleation.
John Millet (139),
Your depiction of what is the null and what the alternative hypothesis may have been valid a century or perhaps even a couple of decades ago, but it is not anymore. When the accumulated evidence for what once was the alternative hypothesis (the Earth is round; GHG cause global warming) is convincing enough for the vast majority of scientists in the field, it becomes the new null hypothesis. AGW is well past this point. That’s how science progresses. See also http://ourchangingclimate.wordpress.com/2008/06/14/how-do-we-know-theres-a-consensus-and-why-does-it-matter/
tharanga:
Sure. He found a correlation there (after fudging the data a bit), whereas he couldn’t find one with high or mid-level clouds. Despite the fact that the GCR flux is obviously greater at greater altitudes.
John Millett,
Horse puckey! There are mountains of evidence favoring anthropogenic causation, and there is precisely zilch favoring GCR or any other natural explanation. It’s science. Don’t like the consensus theory? Find some evidence that contradicts it. Thus far, the denialists efforts in this regard have ranged from woeful to mendacious.
Tad Boyd,
WRONG!! Stats isn’t about overcoming GIGO, it’s about separating what isn’t garbage from the garbage. Visit Tamino’s blog. He’s got an excellent post on Kullback-Liebler Information up. You can learn this stuff.