Rasmus. You wrote that “There is the possibility of the presence of a common cause that may have affected the various isotope records (representing both CRF and ‘climate’)”. It is worth alerting our readers that this isn’t merely a possibility, but a well established fact! For the Vostok, Antarctica, record shown in Figure 1, we know that the reason 10Be concentrations increase when the temperature indicator decreases is that the 10Be flux has been diluted by lower snow accumulation rates characteristic of colder climate. This has been well established since at least 1989, when Jouzel and others pointed it out in a paper in Quaternary Research. Every study of 10Be since that time has backed this up. For example, the GISP2 ice core record from Greenland similarly shows an approximate doubling of 10Be concentrations during the last glacial period when we know with 100% certainty that accumulation rates of snow had halved, demonstrating that there was no change in the 10Be production rate and therefore no change in the cosmic ray flux. – eric
As background to this topic, a good paper to read is C02 and Climate Change by Crowley and Berner, Science vol. 292 (5518): 870-872 , 4 May 2001. The dispute concerns:
As discussed by Veizer et al. there is a major discrepancy during the mid-Mesozoic (120 to 220 Ma) between cold low-latitude temperatures deduced from the oxygen isotopic composition (Î´18O) of fossils and high levels of CO2 and net radiative forcing. The low-latitude Î´18O data are at variance with other climate data that show high-latitude warming and an absence of large-scale continental glaciation….
The persistent Phanerozoic decorrelation between tropical Î´18O and net radiative forcing demands a more comprehensive explanation….
The point being that these very ancient discrepancies exist but, as noted in the post (follow the “controversial” link) the correlation with CRF over geological time with temperature as measured by proxy data has not been established. Certainly, there is no reason to believe that CO2 as a climate driver has been undermined in any way, especially on shorter time scales.
“… The role of CRF as a driver for climate is indeed contriversial, and this fact is not acknowledged in the paper.”
“Indeed controversial” is academic language; but to politicians, this sounds like ‘praising with faint damnation’ — a politician is apt to assume “is indeed controversial” means “is a hot research area” rather than “was asserted in one paper that used at best controversial methods to reach its claimed conclusion” — eh?
Oh — and check the spelling — “contriversial” looks like either a Freudian typo or an intentional pun. Maybe it’s a legitimate word for contrived results — I’m far out of touch with academic jargon (grin).
[Response:Sorry for my mispelling - should be fixed now... -rasmus]
I would be interested to know what you think of a model by a professor in my department, Bose Nordell. His main point is that all the fossil fuels we use heats up the earth since we are using ‘trapped’ energy.
Thanks for the info people.
Can I point out that ultimately we need to build sustainable systems if we are to consider our survival as a civilisation into the future. These arguments, while worthy and interesting, do not effect the imperative of our current situation. Burning fossil fuels and nuclear power are both limited in duration and polluting and therefore unsustainable. We need to get it right and if there is any question of environmental damage we need to do it now. For info on how you can personally do this easily see http://www.yeswecandoit.org
Hi again and thanks for the editing… but the question is more complex then the answer on that other blog, but I understand if you don’t have time to look in on it.
[Response: I did take a look at the paper and William is correct: This can't be right. As the comment from Covey et al makes clear, he is calculating a sensitivity to surface energy fluxes that is almost 100x larger than standard estimates of the climate sensitivity. This is most likely because his radiative model does not have any atmospheric mixing, and therefore the response to near-ground fluxes is hugely overestimated. The basic comparison should be with the net forcing (around 1.8 W/m2 from GHG, solar, aerosols etc.) and the 0.02 W/m2 from thermal pollution. The latter is negligible. -gavin]
[Response:There is some discussion of the paper, finding its results implausible, on the newsgroup sci.env - William]
The questions on the CRF-climate link are legitimate. Recent sun-cloud connections have a decreasing correlation with CRF, but a good correlation between (low) clouds and solar irradiance, see figure 1 in http://folk.uio.no/jegill/papers/2002GL015646.pdf
Also in the 6 May 2005 Science, there is an article which finds a long-term link between solar intensity (based on 14C variations) and monsoon intensity over the past 9000 years…
Still, while there are several theories, there is no direct proof of what physically drives the sun-climate connection. What is clear, is that the influence is larger than what is mostly included in current models as direct insolation only.
Further, in more recent times, there is a very close CO2-temperature relationship in the Vostok (and other) ice cores. But there is a lag of CO2 after temperature of some 600 years during deglaciations, and several thousands of years during the onset of new ice ages. While the overlap during deglaciations is large (which makes it near impossible to make any estimates of relative forcings), during the start of the last ice age, there was no overlap: CO2 started to decrease (some 40-50 ppmv) when the temperature was already near it’s minimum. See: http://www.ferdinand-engelbeen.be/klimaat/co2_temp_ice.html
A later correction by Vimeux e.a. (last page/graph for Vostok) of the deuterium/temperature trend did change the amplitude of the temperature variation, but not the timing. The long lag of CO2 is probably not the result of timing errors between ice age and gas age in the ice core, as methane more closely follows the temperature record (for the timing, see also the discussion at UKweatherworld).
This means that a change of 40-50 ppmv of CO2 has no measurable effect on temperature… That doesn’t mean that there is no effect at all, but it is smaller than implemented in current models.
If one looks at all recent pre-industrial time scales, one sees either a lagged overlap between CO2 and temperature or a lag where CO2 follows temperature. That was the case for the 8.2 ka event (stomata data), the Taylor Dome for last millenium (temperature data not present anymore) and even during recent times: CO2 increase variations follow sea surface temperatures (El NiÃ±o) superimposed over the industrial trend…
[Response: Ferdinand, in your response to one of our earlier posts, you said something about the Law Dome data having "disappeared from the internet". In this post you say the same about Taylor Dome. I suspect you mean Law Dome, but in any case I would be surprised if data from one of the National Data Center's is no longer available. Can you clarify? What data sources are supposedly no longer supplying the data? - eric ]
Thanx for taking time, I’m a bit out of my field here… I’m an “environmental” engineer specializing in geochemistry… but I try to read al the news on climate changes and GHG since it really interests me
and btw, this work by Nordel is done on his spare time and by students, he has not had any resourses for research yet…
I’ve read the paper by Bo Nordell and it is junk. Here is as summary I wrote in sci.environment after having read it:
“The difference between the surface of the Earth and space is 33 degrees.
Geothermal heat produces about 0.07 W/m^2 heat. and if this causes 33
degrees heating the climate sensitivity must be 470 K/W/m^2. Thermal
pollution is 0.02 W/m^2 and will thus give a heating of 0.02*470= 9 K.
The mathematics he uses reduces this by a factor of 3, but essentially
this is his argument.”
To Nordell the sun seems to be just a small inconvenience, not the source of the greenhouse effect.
The paper does in a way fit in this thread. Just like astrophysicists starting to study climate tends to blame everything on the sun, Bo Nordell who works on extracting heat from boreholes see everything in that perspective.
[Response:Thanks Thomas. I've written a bit more about this here, which will point you to replies to Nordell just published in the same journal, if you haven't seen them already - William]
Yes, I agree with many of your remarks. The bulk of the evidence points toward CO2 as an amplifying feedback, not a driver during the Ice Ages. Caution is warranted for even longer time scales.
However, the constructed CO2/temperature graph (Geocarb III/Paleomap) in your first link is highly suspect; the graph reconstruction is much too precise and does not reflect large uncertainties in the data. Look at the results at CO2 as a primary driver of Phanerozoic climate for example, especially figures 1 and 2 (GSA Today, March 2004). I can only conclude that the graph was constructed to score some political point.
As I said, there are certainly CO2/Climate discrepancies in the Phanerozoic data. Given the enormous uncertainties (for continental configurations, ocean currents, amount of volcanism, etc) in reconstructing these records, it would be suspicious and surprising if there were not such mismatches. Reconstructing ancient carbon cycles is really hard to do and once again climate models using the best available proxy data are our best bet. Most scientists working on this do conclude, however, that there is a reasonable 1st order approxmation between CO2 and climate.
Finally, as all this relates to the post concerning the work of Veizer: no Phanerozoic correlation (let alone attribution) has been established with respect to CRF/GCR. If this premise is not established, nothing further can be said about what’s going on now during our unsupervised perilous experiment with Earth’s climate. It appears that CO2 levels have not been this high since the Eocene. And as Rasmus shows, it is straightforward to demonstate that CFR is not the cause of industrial age warming.
[Response: Readers interested in the question of CO2 lag/lead vs. temperature should read J. Severinghaus's post, one of the first ones up on RealClimate, here. --eric]
Indeed it was Law Dome, not the Taylor Dome… I had written that from memory, but as my memory is not anymore what it was 40 years ago…
What I meant was a graph on the Internet, showing the Law Dome ice core CO2 variations, lagging the temperature variations with some 50 years (with ~10 ppmv/K, similar to the factor found over the Vostok ice core trends). But all graphs now only show the CO2 variations and the NOAA databank only contains the CO2 data. I haven’t found the temperature data anyway, which might be of interest to see the CO2-temperature lag, while it seems that the temperature data were calculated (see: IPCC: “Recent series obtained at Law Dome, another coastal site of East Antarctica, show instead a cold reversal preceding the Younger Dryas as in other Antarctic records”. But it is possible that the graph was a mix of CO2 data from Law Dome and temperature data from a different site/proxy.
Btw, there is a lot of discussion between stomata researchers and ice core researchers nowadays. Stomata data show a much larger variation of CO2 in the last millenium (besides higher values in general), in part caused by the smoothing effect of relative slow closing air bubbles in ice cores…
What really disappeared from the NOAA database is the temperature reconstruction of China, which I had downloaded from there. Similar trends for China can be found in stalagmite data graph # 3…
Just wanted to check. This paper was peer reviewed? Cause the mistakes you describe are ones you would expect peer review to catch. I guess it depends on which peers do the reviewing and how much time they spend.
[Response: We were wondering about this as well. As it turns out, the two reviewers of the journal are named in the acknowledgement, and they are both not climatologists. (Unusual that they did not do an anonymous review, and interesting what the author thanks them for.) That explains why those errors were not caught. But it raises the question why the journal chose to have a highly controversial (to say the least) paper on climate change reviewed only by non-climatologists. Imagine someone writing a paper claiming smoking is not harmful, reproducing unscientific PR material from sources close to the tobacco industry, and the paper not even being reviewed by a cancer expert but by a dentist and a vet! In my view, this is fully analogous to what happened here. -stefan]
I will try to show that CRF explanation for the recent global warming is easy to rule out
and comment #12 states that
…it is straightforward to demonstate that CRF is not the cause of industrial age warming.
These are incorrect statements. What you present are some issues that a CRF theory (maybe) has to explain. That is something completely different than showing that it is easy to rule out.
[Response:I show that there is no proof supporting the notion that CRF is responsible for the most recent global warming. On the background of our physical understanding and the empirical data - i.e. the lack of trend in the CRF record (as well as other solar proxies such as 10.7 cm flux) - the notion is inconsistent with our understanding of how the world works. The hypothesis proposed by Svensmark and others is that the CRF affects the ionisation of aerosols and the number of cloud condensation nuclei (CCN) , which again affects the fraction of low clouds and the planetary albedo. This implies that the CRF levels must have systematically decreased over time, causing a long-term decrease in the low cloud fraction and hence a long-term reduction in the planetary albedo, that again would be responsible for the warming. This explanation is definitely at odds with the empirical data, and according to Carl Popper, falsified. Could there be other explanations for climate change, involving CRF? Perhaps, but new hypothereses must be postulated before they can be tested. Thus, we can only falsify known hypotheses and it's impossible to test the unknown. -rasmus]
Comment by Mats Holmstrom — 23 May 2005 @ 12:15 PM
RE #9, that CO2 may be lagging (or caused by) warming should not give anyone solace. We know that GHGs, including CO2, naturally keep earth warming, so it is reasonable to expect additions of GHGs into the atmosphere would increase that warming even without evidence & we do have increasing levels of evidence. Now, if warming also causes increased CO2, then we may be talking about a positive feedback loop in which the warming spirals upwards, which amplifies the warming effect of whatever CO2 we humans contribute to the atmosphere.
Comment by Lynn Vincentnathan — 26 May 2005 @ 5:34 AM
Lynn, there is no doubt that CO2 is a greenhouse gas and the extra addition by humans will give an extra warming. The discussion is about how much that will be, or the difference between a benign warming and a disaster.
Therefore it is of interest to know what the influence of temperature on CO2 and vv. was in pre-industrial times. What we have seen – until now – is that CO2 always lags temperature changes, never leads, be it that there are large overlaps in most cases and sometimes synchronism. And that a change of 40-50 ppmv CO2 had no measurable influence on temperature (during the onset of the last glaciation), while several models imply that CO2 was responsible for halve of the change in temperature (or halve of the 8 degr.C for 80 ppmv increase in CO2 at the onset of the last deglaciation). But as CO2 acts the same for both ways (cooling and warming), either current climate models overestimate the (historical) role of CO2, or the measurements need some correction.
Dave, thanks for the links (especially the Berner one). They reveal the close relation between CO2 and temperature (within the error margins of all the proxies), but don’t solve the height of the influence of one to the other. Methane may be a different story, as that induces water at (near stratospheric) heights.
Eric, I had no possibility to react on Severinghaus’ point that Cuffey and Vimeux have solved the lag of CO2 after the temperature drop during the last glaciation, because the discussion was already closed. In fact, Cuffey and Vimeux did not solve the lag, they only corrected the temperature derived from deuterium/hydrogen ratio, which gives a more sinusoidal curve for temperature changes (and a better correlation between CO2 and temperature), but it didn’t change the timing: CO2 starts to decline, some 1000 years after the temperature reached it’s minimum.
[Response:If it were indeed true that CO2 always lags temperature changes, never leads (which I don't believe) then what you would have proved is that past analoges are of limited value to assessing the present warming, because in this case we do know that the forcing if from GHG's, since we know the CO2 increase is anthro - William]
Dear colleagues, I believe it would be only fair to add the folloving to the “critique” of Veizer as his response:
It would be a relatively easy task to compile a lengthy list of model deficiencies and failings, but because I appreciate the fact that progress in science is incremental, I prefer not to do it. It is my firm belief that the climate debate will ultimately be decided by the merits of the most logical case, not by the demerits of the alternatives or by personalisation of the discourse and advocacy. I only ask that those researchers that wish to arrive at their own judgement of what is it that I am really saying can do so by reading the entire article in its context (available under supplementary material). Please note that is my personal preference to confine any further discourse to scientific ways and means.
[Response:I totally agree that outcome of any scientific debate should not be done by demetits or personalisation of discourse and advocacy. I have tried to make it clear that this post was a critique of the paper and the hypothesis of a Celestial driver, not a personal criticism. But at the same time, it's important to keep in mind that science is a ground on which trial and error over time leads to progress, and it would be wrong to discount wrong hypotheses all together as completely worthless - they do also play a role in this setting by providing a kind of 'dynamic force' and keep the debates going. Even protagonists of ideas that over time turn out to be wrong deserve some credit in my opinion. If I kept the post completely anonymous, wouldn't I rob you of this credit? Besides, giving proper reference is important so other scholars know exactly what I'm talking about. But in the end, it's the combination of empirical evidence and logical reasoning that must decide between conflicting explanations. The reader would definitely benefit from having access to the entire article, and thanks (to Veizer and editor of Geoscience Canada) for making your entire paper available for the RealClimate readers! (you may need to scroll down the page in order to find it) -rasmus]
GCR’s, Clouds, and Climate, Oh My!
If you were at a BBQ with a group of atmospheric scientists, and wanted to raise some hackles, there are several subjects that are notoriously easy to get people riled up… …Talk of Hockey Sticks, Inhofe, Crichton, Coulter, and you’re …