Just when we were beginning to think the media had finally learned to tell a hawk from a handsaw when covering global warming (at least when the wind blows southerly), along comes this article ‘In Ancient Fossils, Seeds of a New Debate on Warming’ by the New York Times’ William Broad. This article is far from the standard of excellence in reporting we have come to expect from the Times. We sincerely hope it’s an aberration, and not indicative of the best Mr. Broad has to offer.
Broad’s article deals with the implications of research on climate change over the broad sweep of the Phanerozoic — the past half billion years of Earth history during which fossil animals and plants are found. The past two million years (the Pleistocene and Holocene) are a subdivision of the Phanerozoic, but the focus of the article is on the earlier part of the era. Evidently, what prompts this article is the amount of attention being given to paleoclimate data in the forthcoming AR4 report of the IPCC. The article manages to give the impression that the implications of deep-time paleoclimate haven’t previously been taken into account in thinking about the mechanisms of climate change, whereas in fact this has been a central preoccupation of the field for decades. It’s not even true that this is the first time the IPCC report has made use of paleoclimate data; references to past climates can be found many places in the Third Assessment Report. What is new is that paleoclimate finally gets a chapter of its own (but one that, understandably, concentrates more on the well-documented Pleistocene than on deep time). The worst fault of the article, though, is that it leaves the reader with the impression that there is something in the deep time Phanerozoic climate record that fundamentally challenges the physics linking planetary temperature to CO2. This is utterly false, and deeply misleading. The Phanerozoic does pose puzzles, and there’s something going on there we plainly don’t understand. However, the shortcomings of understanding are not of a nature as to seriously challenge the CO2.-climate connection as it plays out at present and in the next few centuries.
The use of the more recent Pleistocene and Holocene record to directly test climate sensitivity presents severe enough difficulties (discussed, for example, here), but the difficulties of using deep-time Phanerozoic reconstructions for this purpose make the Pleistocene look like childs’ play. The chief difficulty is that our knowledge of what the CO2. levels actually were in the distant past is exceedingly poor. This situation contrasts with the past million years or so, during which we have accurate CO2. reconstructions from ancient air trapped in the Antarctic ice. Obviously, if you don’t know much about how CO2. is changing, you are poorly placed to infer its influence on climate, even if you know the climate perfectly and nothing else is going on besides variation of CO2.. But, neither of these latter two conditions are true either. Our knowledge of climates of the distant past is sketchy at best. Even for the comparatively well-characterized climates of the past 60 million years, there have been substantial recent revisions to the estimates of both tropical (Pearson et al., Nature 2001) and polar (Sluijs et al, Nature 2006) climates. Most importantly, one must recognize that while CO2. and other greenhouse gases are a major determinant of climate, they are far from the only determinant, and the farther back in time one goes, the more one must contend with confounding influences which muddy the picture of causality. For example, over time scales of hundreds of millions of years, continental drift radically affects climate by altering the amount of polar land on which ice sheets can form, and by altering the configuration of ocean basins and the corresponding ocean circulation patterns. This affects the deep-time climate and can obscure the CO2-climate connection (see Donnadieu, Pierrehumbert, Jacob and Fluteau, EPSL 2006), but continental drift plays no role whatsoever in determining climate changes over the next few centuries.
Let’s take a closer look at the question of CO2 variations over deep time. In contrast to the situation for the late Pleistocene, there is no one method for reconstructing CO2 at earlier times which is fully satisfactory. Methods range from looking at carbon isotopes in microfossils to looking at the density of pores on fossil leaves, with many other exotic geochemical tracers (e.g Boron) coming in in recent times. There is also some data for the very early Earth associated with the CO2 conditions under which certain exotic minerals (uraninites and siderites) form. None of the methods is unambiguous, and none provide information about other greenhouse gases that might be playing a role (though there may be some hope to do something abou methane). As an example of the difficulty faced by the field, take a look at the compilation of various estimates of CO2 since the Permian presented in the following figure (From Donnadieu et al, G3, in press; the red squares come from an attempted geochemical model fit to the data. The data set comes from Royer et al. (2004) and is available here).
By the time one gets back to the Permian, the error bars are huge. At earlier times, the estimates are even more problematic. Broad’s article does make reference to a very interesting paper by MIT’s Dan Rothman, writing in PNAS. This paper attempts a peek at the CO2 over the past 500 million years, using a clever and novel reconstruction technique. It is innovative, but far from the last word on the subject. Broad inappropriately cherry-picks Rothman’s statement that there appears to be no clear connection between warm climates and CO2 (except in "recent" times, about which more anon). However, Broad’s article neglects all the caveats in the paper, which clearly point to the real problem being that the reconstructions of CO2 and climate over such time scales are so uncertain that it’s not clear that the data is up to the task of teasing out ssuch a connection.
Even in Rothman’s reconstruction, during the past 50 milllion years — when the data is best and continents are most like the present — the long term cooling trend leading into the Pleistocene is clearly associated with a long term CO2 decline. This is not our main reason to infer that increasing CO2 will warm the climate in the future, but insofar as the data supports CO2 decline as a main culprit in the long slide from the Cretaceous hothouse climates of 60 million years ago to the cold Pleistocene climate, it also lends weight to the notion that as industrial activity busily restores CO2 to levels approaching those of the Cretaceous, climate is likely to turn the climate clock back 60 million years as well. From Broad’s flip dismissal of the CO2-climate connection in the "recent" part of the record, the reader would never guess at the length and particular significance of this period.
And then, too, the tired old beast of Galactic Cosmic Rays (GCR) raises its hoary head in Broad’s article. The GCR issue has been extensively discussed elsewhere on RealClimate (e.g. here and here) On one level the GCR idea is another instance of the problem that Phanerozoic climate variations may have had many causes, giving rise to a false appearance of decorrelation between climate and CO2. Whatever role GCR may have played in deep time climate, the climate of the past century and its attribution to CO2 is a wholly different kettle of fish, since in modern times we have direct observations of GCR and they are not doing anything of a sort that would cause the observed warming — to say nothing of the fact that one would still have to argue away the basic radiative physics which makes CO2 affect the planet’s radiation budget. We repeat: There has been no recent trend in cosmic rays that could conceivably account for the recent warming, even if the GCR proponents were right about the physical mechanism underpinning their theory. This is made abundantly clear in this recently published article. Further, whatever was going on in the past, the present observations do not support the supposed cloud-GCR connection that is supposed to mediate the climate effect. That’s not the end of the story, for there are also severe methodological difficulties in the way the GCR proponents have attributed Phanerozoic change to GCR rather than CO2, and also severe conceptual difficulties in the supposed physical link between clouds and GCR.. Some of these difficulties may ultimately be resolved and allow a more fair test of the possibility that GCR influences played some role in the past. Surely, the play given to Veizer and Shaviv in the context of Broad’s article is an instance of false balance of the worst sort. The possibility that the GCR theory may play some role in deep-time Phanerozoic climate is eminently worthy of further consideration, but the way its major proponents have used the theory in attempts to undermine forecasts of near-term warming is unjustified.
Besides the broad-brush errors discussed above, Mr. Broad commits a number of lesser climatological faux pas, in areas where he really ought to know better. He refers to CO2 as "blocking sunlight" (whereas it’s actually thermal infrared which CO2 affects). He says that CO2 traps heat "in theory." This is a lot like saying that a bowling ball dropped from an airplane will fall to the ground "in theory." There is indeed a theory involved in both cases, but the use of the phrase gives a completely wrong picture of the certainty of the phenomenon. There is no more doubt about the heat-trapping effect of CO2 than there is about the physics that causes a bowling ball to fall. Broad also says that the greenhouse effect of CO2 "plateaus" at high levels. This is a botched attempt to describe the well-known logarithmic radiative forcing of CO2, incorporated in every climate model since the time of Arrhenius. There is no "plateau" where CO2 stops being important. Every time you double CO2, you get another 4 Watts per square meter of radiative forcing, so that the anticipated climate change between present CO2 and doubled CO2 is comparable to that between doubled CO2 and quadrupled CO2. In fact, as one goes to very high CO2 levels (comparable to the Early Earth), the radiative forcing starts to become more, rather than less, sensitive to each further doubling (something that can be inferred from the radiative forcing fits in Caldeira and Kasting’s 1992 paper in Nature).
Let’s not lose sight, however, of the essential conundrum posed by Phanerozoic climate, particularly by the warm climates of the Cretaceous and Eocene. Current climate models do not reproduce the weak pole to equator gradients believed to characterize these climates, and have trouble warming up the polar climates enough to melt ice and eliminate continental winter without frying the tropics more than data seems to permit. Maybe there’s something wrong with the data, or maybe there are currently unknown amplification mechanisms that make the switch from a moderate Holocene type climate to a hothouse more catastrophically sensitive to CO2. This truly must give us pause as we contemplate the experiment of doubling CO2 in the next century. It’s certainly an experiment that would help to resolve some of the mysteries of Phanerozoic climate, but we’d on the whole prefer to see the mysteries resolved by improved studies of past climate instead.
Update: See Tom Yulsman’s commentary on this post and the broader issues.
Ancient Climate Studies Suggest Earth On Fast Track To Global Warming
by Staff Writers
Santa Cruz CA (SPX) Feb 16, 2006
Human activities are releasing greenhouse gases more than 30 times faster than the rate of emissions that triggered a period of extreme global warming in the Earth’s past, according to an expert on ancient climates. …
http://www.terradaily.com/reports/Ancient_Climate_Studies_Suggest_Earth_On_Fast_Track_To_Global_Warming.html
Text also at:
http://groups.yahoo.com/group/ClimateArchive/message/2816
Here’s an extract from Shaviv & Veizer. Note the difference in tone between this speculative description of a possible new mechanism and the Broad article. Note also the dearth of quantification:
Growing evidence, such as the correlations between paleoclimate records and solar and cosmic ray activity indicators (e.g., 10Be, 14C), suggests that extraterrestrial phenomena are responsible for at least some climatic variability on time scales ranging from days to millennia (Friis-Christensen and Lassen, 1991; Tinsley and Deen, 1991; Soon et al., 1996; Svensmark, 1998; Beer et al., 2000; Egorova et al., 2000; Soon et al., 2000; Björck et al., 2001; Bond et al., 2001; Hodell et al., 2001; Kromer et al., 2001; Labitzke and Weber, 2001; Neff et al., 2001; Todd and Kniveton, 2001; Pang and Yau, 2002; Solanki, 2002). These correlations mostly surpass those, if any, for the coeval climate and CO2. Empirical observations indicate that the climate link could be via solar wind modulation of the galactic cosmic ray flux (CRF) (Tinsley and Deen, 1991; Svensmark, 1998; Marsh and Svensmark, 2000; Todd and Kniveton, 2001; Shaviv, 2002a, 2002b) because an increase in solar activity results not only in enhanced thermal energy flux, but also in more intense solar wind that attenuates the CRF reaching Earth. The CRF, in turn, correlates convincingly with the low-altitude cloud cover on time scales from days (Forbush phenomenon) to decades (sun spot cycle). The postulated causation sequence is therefore: brighter sun -> enhanced thermal flux + solar wind ->muted CRF .> less low-level clouds -> less albedo -> warmer climate. Diminished solar activity results in an opposite effect. The apparent departure from this pattern in the 1990s (Solanki, 2002) may prove to be a satellite calibration problem (Marsh and Svensmark, 2003). The CRF “cloud-cover” climate link is also physically feasible because the CRF governs the atmospheric ionization rate (Ney, 1959; Svensmark, 1998), and because recent theoretical and experimental studies (Dickenson, 1975; Harrison and Aplin, 2001; Eichkorn et al., 2002; Yu, 2002; Tinsley and Yu, 2003) relate the CRF to the formation of charged aerosols, which could serve as cloud condensation nuclei (CCN), as demonstrated independently by ground-based and airborne experiments (Harrison and Aplin, 2001; Eichkorn et al., 2002).
Finally, despite the copious referencing for other links in his argument, he gives no evidence that global cloudiness is in fact decreased during sunspot maxima and Forbrush events.
#40 Raypierre comment :
so far there isn’t any viable competing theory. The GCR idea isn’t even close to being quantified well enough to be tested. In that sense, as a theory “it’s not even wrong.”
Of course, I was not thinking to GCR when I posted my comment. More simply, I refer to millenial-scale and geological-scale solar forcing (radiative and orbital) – whose GCR-cloud effect could be a retroaction (but no proof of that for the moment, I agree). I don’t know if and how we can exclude this forcing for Pleistocene T variations you described as mainly CO2-induced.
What is makeing humans extinct will be:
– rising sea levels
– drought
– Heatwaves
– No food
– No clean water
– plaques
– Catastrophic weather events on a daily/weekly base
– war over clean water and food
And based on PETM and similar events which ongoing around 100.000 years there is enough time for humans to becoem extinct.
If not – than this survivors will not have a life we life today it will be underground – no sun and not much living on the earth.
The PETM took a few 1000 years till it ‘arrived’ – the diffrent this time is we putting more greenhouse gasses into the air (exalerating) and faster.
http://en.wikipedia.org/wiki/Paleocene-Eocene_Thermal_Maximum
Also a diffrent chemistry of the air will manipulate species evolution (Oxygen levels).
This has been allready documented on small genoms (fruit flys for a fact, which got a fast birth rate).
[Response: Don’t forget that the biggest change in chemistry will be the acidification of the ocean. This would be a disaster in waiting even if CO2 caused little or no warming. The chances of human extinction seem pretty low to me, though a lot of other species will likely go extinct and there is a lot of bad stuff that could happen short of extinction of the humans. –raypierre]
On the subject of solar activity, just noted the following Raymond Muscheler paper in press at QSR:
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBC-4MBC585-1&_user=125872&_handle=V-WA-A-W-CC-MsSWYVW-UUA-U-AAZZUVYDBW-AAZBZWECBW-ZYBBEDVB-CC-U&_fmt=summary&_coverDate=11%2F13%2F2006&_rdoc=1&_orig=browse&_srch=%23toc%235923%239999%23999999999%2399999!&_cdi=5923&view=c&_acct=C000010240&_version=1&_urlVersion=0&_userid=125872&md5=9f1527622976d0cf6419f18bf5158c89
The abstract reads:
Identification of the causes of past climate change requires detailed knowledge of one of the most important natural factors�solar forcing. Prior to the period of direct solar observations, radionuclide abundances in natural archives provide the best-known proxies for changes in solar activity. Here we present two independent reconstructions of changes in solar activity during the last 1000 yr, which are inferred from 10Be and 14C records. We analyse the tree-ring 14C data (SHCal, IntCal04 from 1000 to 1510 AD and annual data from 1511 to 1950 AD) and four 10Be records from Greenland ice cores (Camp Century, GRIP, Milcent and Dye3) together with two 10Be records from Antarctic ice cores (Dome Concordia and South Pole). In general, the 10Be and 14C records exhibit good agreement that allows us to obtain reliable estimates of past solar magnetic modulation of the radionuclide production rates. Differences between 10Be records from Antarctica and Greenland indicate that climatic changes have influenced the deposition of 10Be during some periods of the last 1000 yr. The radionuclide-based reconstructions of past changes in solar activity do not always agree with the sunspot record, which indicates that the coupling between those proxies is not as close as has been sometimes assumed. The tree-ring 14C record and 10Be from Antarctica indicate that recent solar activity is high but not exceptional with respect to the last 1000 yr.
Raypierre: You say: “I can tell you how CO2 causes warming and how much, and what factors tend to cause it to change.”
Raypierre, so can I! But I am still a little unclear on your hypothesis. Are you saying that other radiative forcings besides CO2 have not been significant contributors to climate change throughout the Phanerozoic? Are you also saying that aerosols are not significant to the present climate? I think you do not intend to answer in the affirmitive to either of these questions.
As far as ascribing significance to aerosols in the geologic past, I was simply envoking uniformitarianism. The physics operates today, so it must have operated in the past. Do you disagree with the physics or uniformitarianism? I think neither.
Raypierre, you go on to say: “Note, too, that even if we knew nothing about earlier Phanerozoic climate there’s plenty of cause in basic verifiable physics and the recent climate observations vs. theory to tell us that CO2 is (almost) certain to cause substantial future warming.”
Since we both agree that Stephan-Boltzmann is a physical law, will you not enlighten the readers by telling us more about the reasons you are not *completely* certain? Are you really that agnostic about the physics?
You also say: “You’re going to have trouble getting soot from forest fires before land plants had evolved. It’s one thing to parrot a laundry list of vague possibilities.”
And you also hung this on me: “If I may paraphrase your stance, it’s “Let’s just burn all the coal and pray for a miracle.”
But I never said either. You were being broadly misleading. Please do not try and win the argument by hooking stupid ideas to me. You seemed rather angry.
Raypierre, I think we probably agree on more than you think, but a reader from the general public might understandably be confused.
[Response: I’ll repeat my challenge in another way: The work of Berner and others has shown how to explain certain major features of the Phanerozoic climate, assuming that sensitivity to radiative forcing is similar to that in standard climate models. The direction of the remaining mismatch, if anything, points toward climate being more susceptible to major changes than standard models predict. This class of theories doesn’t by any means explain all features of Phanerozoic climate, but can you come even THAT close with any quantified model that has low sensitivity to CO2? Remember that if you are invoking any hypothetical stabilizing feedback mechanism (e.g. Lindzen’s Iris) for consistency you have to apply that stabilization to all radiative forcings on an even footing. That comment applies to volcanic aerosol forcing, as well as hypothetical cloud forcing from GCR (if the proponents of that theory ever manage to get halfway reliable quantifications of the forcing).
As for “praying for a miracle,” what else would you call it if you’re going to argue for not worrying about CO2 emissions on the basis of some possible stabilizing feedback which might possibly be revealed someday by the Phanerozoic studies, but for which there is currently no evidence whatsoever (and which indeed would contradict most of the rest we know about climate physics)? And if you’re sincerely worried about the possibility that the public might get “confused” you ought to look closer to home, and specifically at the AAPG’s endorsement of Crichton’s “journalism.” –raypierre]
RE: #56 – Also, he downsized your “soot and volcanic ash” into “soot.” Of course there was volcanic ash across the Phanerozoic.
The number of possible forcings over geologic time is indeed bewildering. I have long been hoping for attention to be paid to this issue, just for curiosity’s sake.
I am glad to see a compilation of CO2 concentrations since the Permian. I was wondering about various CO2 regulating effects. For instance, the Hercynian mega-cycle would potentially yield a CO2 drawdown similar to that proposed for mechanical weathering related to Tertiary mountain building (how sure is the Tertiary drawdown attributed to this cause btw.?). Similarly, the later Cimmerian mega-cycle.
On exotic forcings, how much effect do 1st/2nd order eustatic sea level changes have? Presumably significant changes in the percentage of Earth’s surface covered by water must have an influence, and when these are due to variable spreading ridge production and ocean basin volumes, then presumably this effect is largely independent of CO2? concentrations.
If this is covered in any of the papers referenced, my excuses. I’ll download them tomorrow.
Re #56: Bryan, I would say it was more impatience than anger. Ray’s point, which you continue to refuse to recognize, is that the argument that anthropogenic CO2 is the predominant influence on the present warming is based on physics and quantified observations. Your assertions, on the other hand, are pure handwaving. Do you imagine that numerous climate scientists haven’t examined each of the factors to which you refer? If you disagree with their conclusions (which are based on the numerous references given on this site), it’s time for you to start putting up some *numbers* to support your case. Absent that, I suggest that it would be more constructive for you to ask questions than to continue making baseless assertions. Note that you’re trying to carry on this argument with someone who (among other things) writes textbooks on climate physics.
I notice that you wrote elsewhere:
“In my view, as geologists, if we want to seriously enter this debate, we must do so not only on the grounds of historical geology, but also on the ground that the debate it is currently being waged, atmospheric physics (Wien’s Displacement Law, Stefan Boltzman Law, the First Law of Thermodynamics, fluid dynamics, ocean heat storage and transfer, etc. etc.). How can we as a society ethically offer up opinions on the validity of anthropogenic climate forcings (and that is mostly about the physics), without having at least some level of basic knowledge? We need to quit pretending that this thing is nothing more than a great political conspiracy, and if we can, challenge it on the basis of solid science (observational and theoretical), not just arm waving. As petroleum geologists, we superbly understand the history of climate change as recorded in the rock record. Painfully however, we really do not understand much about the physics (incredibly complex and numerous coupled interactions of multiple laws) governing these changes. Since we adhear to uniformitarianism (present is key to past), maybe we should break down and begin learning something new about the present.
“I would offer an analogy: If we are arguing with a reservoir engineer as to whether or not there are enough reserves left to justify the development well we are proposing, it helps us if we know some fundamentals of basic reservoir engieering. We become much more persuasive if we can show the engineer that we have already calculated the reserves using his beloved equations. Try this sometimes. It works!”
Reasonable advice both from and to a petroleum geologist, IMHO. You could start with re-reading the extensive replies to your comment #5 above.
Finally, regarding your accusation that Ray must be “agnostic” about the physics since he ascribes a degree of uncertainty to predictions of additional warming due to CO2, it seems very strange that someone with even a modicum of scientific training would be confused on this point.
#54 Raypierre comment :
“Don’t forget that the biggest change in chemistry will be the acidification of the ocean. This would be a disaster in waiting even if CO2 caused little or no warming. The chances of human extinction seem pretty low to me, though a lot of other species will likely go extinct and there is a lot of bad stuff that could happen short of extinction of the humans.”
Again, I disagree with such a pessimistic and one-sided view. As far as I know, biological modelisation of planktonic response to acidification (low. 0,1 to 0,4 pH from now to 2100) is still in its infancy. Forams and coccoliths have a rather high rate of reproduction – a not-so-bad adaptative profile – and these species have survived to many abrupt climate changes of the past million years. Preliminary lab. experiences cannot be accepted as realistic simulations : Riebesell et 2000, for example, upwarded ambient atmosphere of a coccoliths monuculture to 800 ppm CO2 in 9 days !! That’s not conclusive for real-word adaptive behavior of theses micro-organisms over the forthcoming nine decades.
I don’t say : there is no problem. But rather : let’s be cautious and avoid the catastrophic claims, or the credibility of science will be seriously weakened.
Re #59: Steve, you said: “Ray’s point, which you continue to refuse to recognize, is that the argument that anthropogenic CO2 is the predominant influence on the present warming is based on physics and quantified observations.”
Steve, I largely agree with Ray (defer to his expertise) on that point. What has given you the idea that I have not recognized his point? I quarrel with RC over giving the public the perception that the community has all of the important climate issues resolved. Yes, there have been many advances in recent years, but the poor model performance in replicating some important climate metrics point to possible potholes which are not being clearly communicated to the public and policy makers. Maybe these are why Ray is not *completely* sure. My argument is that the climate science community should not cease (by force of tyranny of the majority) to think critically about many of these forcings and feedbacks which still are poorly understood. Maybe they are, but I am not seeing the papers.
> Acidification
Check the more recent work citing that article with Google Scholar, including newer work by Riebesell.
http://web.awi-bremerhaven.de/Publications/Ros2004a.pdf.
And much else on acidification is news.
The ratio of species changes dramatically, that’s the issue. This isn’t about extinction of specific primary producer species, it’s about which ones predominate and which ones become more susceptible to viruses and bacteria as calcite becomes soluble in surface sea water in about 2100.
Oceanography: Sick seas
Jacqueline Ruttimann
SUMMARY: The rising level of carbon dioxide in the atmosphere is making the world’s oceans more acidic. Jacqueline Ruttimann reports on the potentially catastrophic effect …
Nature 442, 978 – 980 (31 Aug 2006)
Atmos. Chem. Phys. Discuss., 6, 7075�7091, 2006
http://www.atmos-chem-phys-discuss.net/6/7075/2006/
Carbonate precipitation in brine � the trigger for tropospheric ozone depletion events
R. Sander1, J. Burrows2, and L. Kaleschke2,*
http://www.copernicus.org/EGU/acp/acpd/6/7075/acpd-6-7075_p.pdf
Suppose we had been observing global cooling instead of global warming. What remedies would have been proposed? “Use all the oil you can!” “Buy really fuel-inefficient cars!” “Don’t use any renewable sources of energy if you can avoid it!”
The human race has always been inclined to blame itself for whatever troubles that arise, and offerings to the gods have always been a part of the solution, may they be in form of slaughtered lambs or giant wind-powered generators. This is the main source of my personal scepticism of any theories of impending climatic doom.
And, if you live in Scandinavia, as I do, retreating glaciers are indeed an ominous sign – but advancing ones are even worse.
Re #49, 50
Raypierre – balderdash? – your comment about my post #49.
First, I didn’t say anything about CO2 in my post and I don’t doubt it is a major factor in global warming.
Second, you then go on to cite the Last Glacial Maximum as evidence of something, more or less helping me make my point that you can’t just cite the past to predict the future.
Third, as for the basic physics, can it tell me when I can start building my beach house on some farm land I’m thinking of buying in South Georgia?
Regarding Post #50, the link goes to a graph covering millions of years. I guess we could find another graph covering billions of years that wouldn’t even show Earth on it. That would be a real big change, right?
Take a look at the last twelve thousand years – http://en.wikipedia.org/wiki/Image:Holocene_Temperature_Variations.png
Re 60+
What if the natural “balanced” climate cycle would bring an iceage?
But due to AGW its not happening – and its just slowering the effect of AGW?
And more importend on the bottomline what helps such hypotetical statement in such a debate?
We should try avoiding any unnatural interference with systems which a) can lead to extinct of the human species – b) Can not be calculated with currrent data/know-how and computer capacity – c) Can bring our planet into a state which is considerate unbalanced in relation to present and past states(climate).
We have the know how today to sustain this “paradies like” planet – under the circumstances and what is on stacks we should act yesterday rather than later.
Cheers
Re #61: Bryan, up in #7 you wrote: “What would also be misleading would be giving policy makers and the public an impression that we now understand all of the complex, non-linear interactions between all the forcings and feedbacks significantly well to forecast future climate with skill across multi-decadal time. Just because Stefan-Boltzmann and Wein are beyond dispute, the best geological evidence available (most of the last 25% of earths history) tells us that CO2 is not the only game in town. It is the very tricky interaction of CO2 with a number of the other forcings that is really the question. To give one example, the role of aerosols and their associated feedbacks is still incompletely understood, but we know to some extent there is a cooling effect. There might be high aerosols and high CO2 (both can be natural and or man-made), and maybe a cooler than expected climate. What about the feedbacks associated with both? How do they all interact?”
A “cooler than expected climate”!? I’d call that a fundamental disagreement (noting that you were referring to future climate rather than to the Phanerozoic, although it appears you were trying to refer to some sort of evidence from the Phanerozoic). There is a big distinction between saying the science is incomplete and that there is a degree of uncertainty about the timing and extent of future warming and saying, as you do, that the uncertainty is large enough to allow for the present warming trend to reverse into cooling. It isn’t.
With respect to your reference to climate models being unable to forecast climate with skill on a multi-decadal basis, I suppose one can define terms to make that a true statement (and rumor has it that there’s even a whole blog devoted to that purpose), but having done so it is dishonest to try to backtrack such a conclusion into questioning what can be known from the physics and observations. Recall that a century ago Arrhenius got an answer (for warming due to climate sensitivity to increased CO2) in the right ballpark without any model as such. It might be useful for you to have a look at this RC post
#62
Yes. I quote the abstract of a more recent paper of Riebesell (2004) :
Abstract Rising atmospheric CO2 and deliberate CO2 sequestration in the ocean change seawater carbonate chemistry in a similar way, lowering seawater pH, carbonate ion concentration and carbonate saturation state and increasing dissolved CO2 concentration. These changes affect marine plankton in various ways. On the organismal level, a moderate increase in CO2 facilitates photosynthetic carbon fixation of some phytoplankton groups. It also enhances the release of dissolved carbohydrates, most notably during the decline of nutrient-limited phytoplankton blooms. A decrease in the carbonate saturation state represses biogenic calcification of the predominant marine calcifying organisms, foraminifera and coccolithophorids. On the ecosystem level these responses influence phytoplankton species composition and succession, favouring algal species which predominantly rely on CO2 utilization. Increased phytoplankton exudation promotes particle aggregation and marine snow formation, enhancing the vertical flux of biogenic material. A decrease in calcification may affect the competitive advantage of calcifying organisms, with possible impacts on their distribution and abundance. On the biogeochemical level, biological responses to CO2 enrichment and the related changes in carbonate chemistry can strongly alter the cycling of carbon and other bio-active elements in the ocean. Both decreasing calcification and enhanced carbon overproduction due to release of extracellular carbohydrates have the potential to increase the CO2 storage capacity of the ocean. Although the significance of such biological responses to CO2 enrichment becomes increasingly evident, our ability to make reliable predictions of their future developments and to quantify their potential ecological and biogeochemical impacts is still in its infancy.
The conclusion is important, and it was the sense of my reply to Raypierre’s excessive alarmism. An other recent work show that pluridecadal variability of 0,1 to 0,3 pH is common in Pacific coral reefs (Pelejero 2005). So life is life, its evolution and adaptation to local conditions is a very complex matter – for this issue, what do we know exactly about functional genomics of calcification in plankton and coral species?
I agree with you that modifications in relative populations dynamics (rather than global extinction) is a most probable consequence of rapid environmental changes predicted for the 21st century.
Re #64: Climate science has already met the necessary standard. Continuing to ask for more evidence after that point has been reached is, well, balderdash.
>Acidification
Links to several other research articles on plankton, acidification, and ocean circulation I won’t repeat here, that I posted at Stoat earlier:
http://scienceblogs.com/stoat/2006/11/a_bit_more_gnawing_on_the_ster.php#comment-258486
This is not iffy stuff, it’s basic acid-base chemistry, according to the scientists reporting it.
http://www.isse.ucar.edu/florida/index.html
There’s a whole lot of recent info available, this just one example.
http://www.ipsl.jussieu.fr/~jomce/acidification/
published in Nature on September 29, 2005 reports that ocean acidification could result in corrosive chemical conditions that would be reached much sooner than previously thought.
Within 50 to 100 years, there could be severe consequences for marine calcifying organisms, which build their external skeletal material out of calcium carbonate, the basic building block of limestone.
Most threatened are cold-water calcifying organisms, including sea urchins, cold-water corals, coralline algae, and plankton known as pteropods–winged snails that swim through surface waters.
[illustrations]
Chemical Saturation State:
Projections for the “chemical state” of the surface ocean for years 2000 (top) and 2099 (bottom) given as the median of 10 ocean models. The magenta colored line (seen only in 2099) separates saturated waters (orange colors) from undersaturated waters (blue colors).
Re 54> What is makeing humans extinct will be:
– rising sea levels
– drought
– Heatwaves
– No food
– No clean water
– plaques
– Catastrophic weather events on a daily/weekly base
– war over clean water and food
It is difficult to understand how sea level rising at mm or even cm rates per year will drown many people.
Drought (presumably resulting in no food) – I believe most peer reviewed studies actually predict total greater food growing capacity in a warmer world.
Heatwaves, no clean water, plaques, war – Those problems are most likely to be solved by a prosperous economy with access to energy, and would likely be made worse by devoting excessive resources to reducing GHG emissions.
Catastrophic weather events on a daily/weekly base – Is there any credible study indicating a sufficient increase in catastrophic weather events to threaten the lives of a significant portion of the world’s population?
Notwithstanding the respectable qualifications of the contributors to RealClimate, I think the credibility of the site is at serious odds with its objectives: I quote, â??RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists. We aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary..â??. However, everywhere on this site I do not observe a balanced view. The aim of this web site looks more like â??â?¦We aim to provide a quick response to stories challenging the greenhouse global warming theory because we believe it is a scientific fact and we will counter with anything we can find that supports our view and our confidence that our climate models are infallible.â?? Why donâ??t you present an objective view of this important issue?
As you dismiss yet another article, again resorting to unnecessarily insulting and arrogant language, perhaps you can explain why the climate of earth 125,000 years ago was warm enough to enable the growth of coral in a temperate latitude off the coast of south west Australia? The evidence for this is a fossilised coral reef sitting 3 to 4 metres above the present sea level. It is estimated to be 125,000 years old. The location (around 33 degrees latitude) is well south of present coral waters.
Re 70> This is not iffy stuff, it’s basic acid-base chemistry…reports that ocean acidification could result in corrosive chemical conditions…
If this is ‘basic acid-base chemistry’, why not honestly say the ocean may become less basic. Is anyone predicting a pH < 7.0? What pH is predicted?
You could click on some of the links and find the answer to your question, along with far more information that I want to retype for you. And you’d have found it yourself, always best.
Re #72: Robert, the period you refer to is the Eemian, which was known to be about 2C warmer (in places) and to have sea level about 6m higher than present. Since the current southern extent of tropical coral is no more than 400km north of the latitude you mention, the presence of that reef doen’t seem remarkable. As to why the Eemian was warmer than the present, at least in some regions, see here.
Regarding the site, please bear in mind that anthropogenic global warming is a scientific fact and that there is no obligation to make room for contrary views if those views are incorrect.
Re 71
U missed something – who talks about drowning?
This happens from many factors forced by rising sea levels. Such as water becomes salted from sea water – the complete economic gets unbalanced and species extinct( Yes new comes to – but into an unbalanced cycle). People are forced to move – leaving all they got – if this happens to millions – maybe u can try to imagine.
And what means “most peer reviews studies”? Do you can provide a link – i doubt it.
Drought brought us many results eg. less food yes – also forces people to move – also killing economics – destroying jobs – Just checkout http://de.wikipedia.org/wiki/Aralsee the image is kinda self explaining.
Also plaques come up from this – also geological events (Sahara winds).
1.
You total messing here around with diffrent events.
2.
You also give ur personal individual few of things which is total wrong.
Your conclusion shows how much u not into renewable energy efforts – see next point.
3.
I think this site gets spamed by paid trolls latly.
4.
To clear ur messy statement do the following.
Point ur browser to google – than click on news – than enter “heatwave”. This brings up news from this year heatwaves which u obvisiously missed out – maybe u are 1 of the few who have no access to american television?
And the image i provided is a bad example its caused by humans – yes because they changed the water fluctuation in these areas.
Cheers
> Acidifcation
Again, basic chemistry is one thing, real life (or developmental and evolutionary biology) another. My purpose is not to say that acidification of oceanic water have no predictable effect, but that predictions are far less simplistic than global extinction spectra. I remind conclusion of Royal Societies rapport (2005), section 3.8 :
On the effects on calcification: It is expected that calcifying organisms will find it more difficult to produce and maintain their shells and hard structures. However, the lack of a clear understanding of the mechanisms of calcification and its metabolic or structural function means that it is difficult, at present, to reliably predict the full consequences of CO2-induced ocean acidification on the physiological and ecological fitness of calcifying organisms.
If we go back to the subject of Raypierre paper here, the problem deals with popularization of climate topics. The more alarmist you are on objectively indecise matters, the less credible you are (for these matters and also for others), because your readers suspect you are animated by a strong prejudice. As we say in French : tout ce qui est excessif est insignifiant.
Hi, just curious again… have this paper bean discussed?
http://www.cato.org/pub_display.php?pub_id=6622
Charles Muller (#64)
The paper you cite (Pelejero 2005) does not go as far as you think it does. It discusses the response of one species of coral in one reef. It does not discount the seriousness of the acidification problem.
Read Pelejero’s own take on the problem
http://www.cosis.net/abstracts/EGU05/04277/EGU05-J-04277.pdf
The Pelejero 2005 is in Science, but its available in a non-subscription version
http://pangea.stanford.edu/research/Oceans/GES205/Pelejero_Science_Preindustrial%20to%20Modern%20Interdecadal%20Variability.pdf
Re #79: Bear in mind that Pat Michaels, the author of this paper, is rather notorious for being in the pay of the U.S. coal industry. It’s rapidly becoming a better idea to simply ignore such things rather than grant them the credibility associated with a refutation.
Unsurprisingly, a quick scan of the linked document shows that he’s up to his old tricks. To list one very obvious example, at the bottom of page five he writes:
“Recently, Overpeck et al. projected a massive melting of Greenland and Antarctica’s ice sheets, resulting in a sea-level rise of 12-18 feet. This is the same sea level that occurred in the last interglacial, about 130,000 years ago. Overpeck et al. made this projection because their model for 2100 gives higher arctic temperatures than in the last interglacial; sea levels rose that much during the interglacial. Nowhere do Overpeck et al. mention that all the available models require thousands of years of warming to melt most of Greenland’s ice and that it must take even longer in Antarctica. A run of three emissions scenarios used for the next 100 years with 18 climate models yields a mean sea-level rise from Greenland of .06 inch per year around 2100. As noted above, all models project that Antarctica gains ice in a warming world.”
So what’s wrong with this statement? See this previous RC post for the details, but the upshot is that at the time Michaels wrote that passage he was well aware that leading modelers (most prominently Jim Hansen and Richard Alley) have determined that the simple melting slab view of melting that’s included in the models Michaels referenced does not reflect reality, and that the dynamic melting that has been observed in the real world will cause a far more rapid collapse of the ice.
#80
Joseph, I agree with you, and never said acidification is not a (potentially) serious problem. Pelejero et al. did find decadal 0,1 to 0,3 pH variations in Flinders reef over the past three centuries, without noticeable modifications of growth for the concerned porites. That was just an example of a local adaptation to local variations (and a reminder of the amplitude of such variations for a south Pacific coral reef). But sure, a lowering of 0,2 to 0,4 oceanic pH over the next century will exert a strong selective pressure on calicfication species.
#81
Thanks for the point Steve, the document have started to “flow” around in Sweden.
Re “Again, I disagree with such a pessimistic and one-sided view. As far as I know, biological modelisation of planktonic response to acidification (low. 0,1 to 0,4 pH from now to 2100) is still in its infancy. Forams and coccoliths have a rather high rate of reproduction – a not-so-bad adaptative profile – and these species have survived to many abrupt climate changes of the past million years. Preliminary lab. experiences cannot be accepted as realistic simulations : Riebesell et 2000, for example, upwarded ambient atmosphere of a coccoliths monuculture to 800 ppm CO2 in 9 days !! That’s not conclusive for real-word adaptive behavior of theses micro-organisms over the forthcoming nine decades.”
On the other hand, coral reefs are dying from acidification all over the world, and they were centers of ocean biological activity. The ocean is in danger from acidification even if natural selection will help some survivors adapt to it. Don’t forget how natural selection works — time and death.
Re “Suppose we had been observing global cooling instead of global warming. What remedies would have been proposed? “Use all the oil you can!” “Buy really fuel-inefficient cars!” “Don’t use any renewable sources of energy if you can avoid it!”
The human race has always been inclined to blame itself for whatever troubles that arise, and offerings to the gods have always been a part of the solution, may they be in form of slaughtered lambs or giant wind-powered generators. This is the main source of my personal scepticism of any theories of impending climatic doom.
And, if you live in Scandinavia, as I do, retreating glaciers are indeed an ominous sign – but advancing ones are even worse.”
Along those lines, what if we had been threatened by a Martian invasion?
There is a difference between magical thinking and drawing conclusions from empirical evidence and experiment. You are wrong to ascribe scientists’ conclusions on global warming to the former.
Re “Drought (presumably resulting in no food) – I believe most peer reviewed studies actually predict total greater food growing capacity in a warmer world.”
Where did you get that idea? As far as I know it’s completely wrong.
If you take the most basic model of all — the area available on a sphere like the Earth — global warming moves agricultural belts toward the poles, which makes them smaller.
#84 : “On the other hand, coral reefs are dying from acidification all over the world, and they were centers of ocean biological activity.”
I disagree. Again, we should be precise in our assertion. Have a look on Royal Societey 2005 report : Acidification is NOT a past and present stress for coral reefs “all over the word” – even for cold-water corals which will be the more concerned by the phenomenon on short term (Lophelia sp. notably). Main actual threats on coral reefs are warming-induced bleaching (catastrophic El Nino 98), human pollutions in lagoons and coastal areas, parasitic invaders (algae, etc.). But acidification per se is not still a problem for reefs and the recent trend is rather clearly positive for some large-studied genus like Porites (for example Buddemeier 2004 : “Calcification rates of large heads of the massive coral Porites increased rather than decreased over the latter half of the 20th century”. On Porites : Bessat 2001, Lough 2000, etc.).It’s difficult to draw global conclusions because of the numerous factors involved in each local conditions. All the more so that even the most extensive surveys do not cover all the coral area and biodiversity. But for that I know, coral reefs do not presently die of the 0,1 pH acidification since pre-industrial times. It does not mean that a 0,4 pH centennal drop is not a serious concern for all calcifying organisms: it is ! In my sense, avoiding premature and catastrophic claims, amplifying research efforts is a the better way to deal with it – except if you have a political agenda and want to impress imaginations for rapid collective decisions. But it’s no more science.
Re #87: I think Charles is correct that the damage to coral reefs that has been seen in the last decade or so is from warming (possibly with an additional effect from acidification, but likely that would be hard to tease out of the data at this relatively early stage) , noting that the tropical seas have warmed more than the global average. It seems entirely plausible that some coral species will do a little better in water that is a bit warmer or a bit more acid, but even more plausible that it will be a different story if they are put into a temperature and acidity range that is well outside of the one in which they evolved.
In the just past issue of the New Yorker (probably still available today), Elizabeth Kolbert has a long article on ocean acidification. I wasn’t able to read the whole thing, but it appears to have a lot of up-to-date material from interviews of many of the leading researchers.
Re #87: Charles, I recall several years ago a popular hypothesis which linked some of the decline of Carribean corals to dust being transported from Africa due to drought and landuse changes there. Can you update me on whether the dust hypothesis ever caught hold?
Perhaps I missed something, but Bill Broad may have been blind-sided by gun-for-hire “scientists” (paid by the black-gold naysayers) who deride anthropogenic climate change because it interferes with business. Thus, his take may have been flavored with doubt, although that does not justify the tone of the story. Tuesdays forray into even more questionable impact “science” without sufficient skepticism or caveats (this was based on an abstract to AGU) does not bode well for readers of Science Times or policy makers who read it.
Agreed, George. That’s why I was hoping he’d come here or otherwise tell us what his sources and references were for what he wrote. The man’s been fooled before, for example he coauthored the primary “nerve gas factory” story used to rush an attack into Iraq. Oops.
[Response: I’m rather disappointed in Broad. I sent him an email pointing out this article and discussion and all I got from him was the response “Thanks for writing. Saw it.” I hope he’s at least reading this discussion, even if he doesn’t seem to care enough to explain how he went so wrong, or even acknowledge the shortcomings of his article. –raypierre]
He does correct errors. Here’s his page:
http://topics.nytimes.com/top/reference/timestopics/people/b/william_j_broad/index.html?inline=nyt-per
re: global warming and agriculture
The farmer plants by the kind of weather he had the year before. Energy in the atmosphere increases variability. So, whether a farmer’s area is colder or warmer, wetter or drier, the extra energy in the atmosphere is going to increase the variability in weather that the farmer can expect.
Re: In reply to comment 52: “Finally despite copious referencing for other links in his [Their. The paper quoted was by Shaviv & Veizer], he gives no evidence that global cloudiness is in fact decreased during sunspot maximum and Forbrush events.”
The following paper “Empirical evidence for a nonlinear effect of galactic cosmic rays on clouds” by, R. Harrison and D. Stephenson, provides evidence that global cloudiness is in fact decreased during sunspot maximum and Forbrush events.
http://www.met.rdg.ac.uk/cag/publications/2006/harrison2006.pdf
“During sudden transient reduction in cosmic rays (e.g. Forbush events), simultaneous decreases occur in the diffuse fraction. The diffuse radiation changes, are therefore, unambiguously due to cosmic rays. Although the statistically significant non-linear cosmic ray effect is small, it will have a considerably larger effect on longer timescale climate variation when day-to-day variability averages out.” [See note end of this comment.]
“This study has found a small yet statistically significant effect of cosmic rays on daily cloudiness that supports the global results from satellite data (Marsh & Svensmark 2000). The method used is independent of the satellite results, and uses date from different sites extending over a longer period.”
Notes & Comments:
1) Harrison and Stephensonâ??s paper discusses GCR modulation effects which are minor as the earth’s magnetic field is currently at a 100kyr maximum. In the next comment, a paper is quoted that provides evidence that the earth’s magnetic field suddenly increases on a 100kyr cycle and that this change and other observed changes in the geomagnetic field (not insolation cycles), is a trigger for glacial terminations and other major changes in the geoclimatic record. The next paper provides an explanation for the 100 kyr eccentricity paradox.
2)Note GCR modulation effects are less when the earth’s magnetic field is high and/or when the sun is at a maximum in its magnetic cycle.
The comment ” the tired old beast of Galactic Cosmic Rays (GCR) raises its hoary head…” [and] “There has been no recent trend in cosmic rays that could conceivably account for the recent warming…” discounts or perhaps completely ignores recent data and analysis that provides support for the hypothesis that GCR modulation is a first order climate forcing function.
What is the evidence that GCR modulation effects on cloud cover have had a major affect on the earth’s climate in the past? How will GCR modulation affect climate in the future?
http://arxiv.org/pdf/physics/0407005
The paper “The Glacial Cycles and Cosmic Rays” by J.Kirkby, A. Mangini, and R. Muller (2004) examines changes in the geomagnetic field, that are concurrent with major planetary temperature changes. Due to GCR modulation effects on clouds, it is hypothesized that a stronger geomagnetic field results in warmer temperatures and a weaker field, colder temperatures. The authors examine deep sea sediments and find as have others that the geomagnetic field peaks at 100 kyr intervals. Further the authors find at termination II (Warming that led to the Eimen interglacial) that the records show that the warming started when insolation was at a minimum. They also find that the termination II warming and other warming events coincide with periodic geomagnetic field maximums.
“In this paper we propose the glacial cycles, rather than being driven by insolation cycles as in the present standard model, are initially driven by cosmic ray changes, probably through their effects on clouds.”
“Recent measurements suggest that long-term records of variation of Earth’s magnetic field – in both strength and magnetic inclination – show orbital frequencies -… The 800 kyr record known as Sint-800 is reported to show no such cycles; however we will present a new analysis here that shows such cycles are in fact present in this record.”
“We present a new spectral analysis of cosmic ray flux recorded in the BE10 content of deep ocean sediments, which shows the present of orbital cycles. Further we present additional results based on the BE10 record and on precisely-dated speleothems that reinforce the causality problem with the Milankovitch model and support our conclusion that cosmic rays appear to be driving the glacial cycles.”
“The worst fault of the article, though, is that it leaves the reader with the impression that there is something in the deep time Phanerozoic climate record that fundamentally challenges the physics linking planetary temperature to CO2. This is utterly false, and deeply misleading.”
Well statistically CO2 is linked to planetary temperature more as an effect not substantially as a cause. So this is a very strange thing to say.
[Response: This is garbage. Where are you getting your information? So tell me your brilliant theory explaining how the high CO2 in the atmosphere of Venus today is a consequence of some other factor which is maintaining the high Venus temperature. Publish it and you’ll be an instant scientific superstar. Your comments seem to be just trolling rather than any earnest attempt at contributing to the discussion, and there are limits to how long you’ll be allowed to just post noise. –raypierre]
Hi, raypierre. Instead of commenting on a single throw-away statement, I would rather get an opinion on the two papers referenced by William Astley. Reading them, I get the impression of a far greater correlation of cosmic radiation and climate than I had been led to believe. The suggestion that glacial cycles are driven by the inclination of the Earth’s orbit around the sun rather than eccentricity is interesting. Is it a coincidence they both have the same period? And all three glacial cycles show up in the ice age record, and eccentricity amplifies some of these cycles, so I have a hard time dispensing with eccentricity.
However, I do not see how much relevance this has to the present climate. The shortest cycle they identify is 100 Ky. And I would like to know just how large this “small but statistically significant” effect is in meaningful units such as watts per square meter.
#87 Bryan, I suppose you refer to Shinn and Griffin hypothesis (transport of pathogens from African dust to Carribean corals). Sorry, I’ve no particular information about these reefs, which are threatened by a lot of factors (including diseases, but also hurricanes, overfishing and pollution). The most recent publication I find around the African dust hypothesis is
Weir-Brush, J.R., V.H. Garrison, G.W. Smith and E.A. Shinn. 2004. The relationship between Gorgonian coral (Cnidaria: Gorgonacea) diseases and African dust storms. Aerobiologia 20: 119-126
Re #97
Let me second the call for Raypierre to do something more than pounce on the #96 post that carelessly used the word planetary when probably Earth was intended.
I’ve never seen a convincing explanation of how temperatures can begin decreasing when CO2 levels are high as they are at the end of each interglacial. Or, is it that for some reason CO2 levels begin decreasing on their own and that is what brings down temperatures â�� some unknown, mysterious regulator of CO2?
About the inclination theory, the inclination of the Earth’s orbit around the Sun has changed over a 100k year cycle for the last million years or so. When there is less inclination, the Earth is cooler. When there is more inclination, the Earth is warmer. Is this just an odd coincidence or is there some link between Earth’s temperature and the inclination. Muller originally proposed that there might be space dust in the orbital plane that came into the atmosphere to cool the planet during times of low inclination. That theory so far hasn’t panned out. So this GCR connection is a second attempt to find a link.
The relevance to the present is that our orbital inclination has been declining since around the start of the Holocene.
Re #97, Blair Dowden, and #99, Jim Cross — I believe these topics have been rather thoroughly gone over on at least two previous threads. I recommend finding and reading those.