Unusually, I’m in complete agreement with a recent headline on the Wall Street Journal op-ed page:
“The Climate Science Isn’t Settled”
The article below is the same mix of innuendo and misrepresentation that its author normally writes, but the headline is correct. The WSJ seems to think that the headline is some terribly important pronouncement that in some way undercuts the scientific consensus on climate change but they are simply using an old rhetorical ‘trick’.
The phrase “the science is settled” is associated almost 100% with contrarian comments on climate and is usually a paraphrase of what ‘some scientists’ are supposed to have said. The reality is that it depends very much on what you are talking about and I have never heard any scientist say this in any general context – at a recent meeting I was at, someone claimed that this had been said by the participants and he was roundly shouted down by the assembled experts.
The reason why no scientist has said this is because they know full well that knowledge about science is not binary – science isn’t either settled or not settled. This is a false and misleading dichotomy. Instead, we know things with varying degrees of confidence – for instance, conservation of energy is pretty well accepted, as is the theory of gravity (despite continuing interest in what happens at very small scales or very high energies) , while the exact nature of dark matter is still unclear. The forced binary distinction implicit in the phrase is designed to misleadingly relegate anything about which there is still uncertainty to the category of completely unknown. i.e. that since we don’t know everything, we know nothing.
In the climate field, there are a number of issues which are no longer subject to fundamental debate in the community. The existence of the greenhouse effect, the increase in CO2 (and other GHGs) over the last hundred years and its human cause, and the fact the planet warmed significantly over the 20th Century are not much in doubt. IPCC described these factors as ‘virtually certain’ or ‘unequivocal’. The attribution of the warming over the last 50 years to human activity is also pretty well established – that is ‘highly likely’ and the anticipation that further warming will continue as CO2 levels continue to rise is a well supported conclusion. To the extent that anyone has said that the scientific debate is over, this is what they are referring to. In answer to colloquial questions like “Is anthropogenic warming real?”, the answer is yes with high confidence.
But no scientists would be scientists if they thought there was nothing left to find out. Think of the science as a large building, with foundations reaching back to the 19th Century and a whole edifice of knowledge built upon them. The community spends most of its time trying to add a brick here or a brick there and slowly adding to the construction. The idea that the ‘science is settled’ is equivalent to stating that the building is complete and that nothing further can be added. Obviously that is false – new bricks (and windows and decoration and interior designs) are being added and argued about all the time. However, while the science may not be settled, we can still tell what kind of building we have and what the overall picture looks like. Arguments over whether a single brick should be blue or yellow don’t change the building from a skyscraper to a mud hut.
The IPCC reports should be required reading for anyone who thinks that scientists think that the ‘science is settled’ – the vast array of uncertainties that are discussed and dissected puts that notion to bed immediately. But what we do have are reasons for concern. As Mike Hulme recently wrote:
[S]cience has clearly revealed that humans are influencing global climate and will continue to do so, but we don’t know the full scale of the risks involved, nor how rapidly they will evolve, nor indeed—with clear insight—the relative roles of all the forcing agents involved at different scales.
…
The central battlegrounds on which we need to fight out the policy implications of climate change concern matters of risk management, of valuation, and political ideology. We must move the locus of public argumentation here not because the science has somehow been “done” or “is settled”; science will never be either of these things, although it can offer powerful forms of knowledge not available in other ways. It is a false hope to expect science to dispel the fog of uncertainty so that it finally becomes clear exactly what the future holds and what role humans have in causing it.
Dealing with the future always involves dealing with uncertainty – and this is as true with climate as it is with the economy. Science has led to a great deal of well-supported concern that increasing emissions of CO2 (in particular) are posing a substantial risk to human society. Playing rhetorical games in the face of this, while momentarily satisfying for blog commenters, is no answer at all to the real issues we face.
Philip Llyod (387) and Zachariah (391)
You will find a great debunking here
http://www.economist.com/blogs/democracyinamerica/2009/12/trust_scientists
Gavin, I was wondering if you’ve read this paper. if you did what you think about it. Could this be what affects the tree ring data after 1960?
A relationship between galactic cosmic radiation and tree rings
Sigrid Dengel, Dominik Aeby and John Grace
Institute of Atmospheric and Environmental Science, School of GeoSciences, Crew Building, University of Edinburgh, EH9 3JN, UK
ABSTRACT
• Here, we investigated the interannual variation in the growth rings formed by Sitka spruce (Picea sitchensis) trees in northern Britain (55°N, 3°W) over the period 1961–2005 in an attempt to disentangle the influence of atmospheric variables acting at different times of year.
• Annual growth rings, measured along the north radius of freshly cut (frozen) tree discs and climatological data recorded at an adjacent site were used in the study. Correlations were based on Pearson product–moment correlation coefficients between the annual growth anomaly and these climatic and atmospheric factors.
• Rather weak correlations between these variables and growth were found. However, there was a consistent and statistically significant relationship between growth of the trees and the flux density of galactic cosmic radiation. Moreover, there was an underlying periodicity in growth, with four minima since 1961, resembling the period cycle of galactic cosmic radiation.
• We discuss the hypotheses that might explain this correlation: the tendency of galactic cosmic radiation to produce cloud condensation nuclei, which in turn increases the diffuse component of solar radiation, and thus increases the photosynthesis of the forest canopy.
http://www3.interscience.wiley.com/journal/122597017/abstract?CRETRY=1&SRETRY=0
I have a couple of questions which I can’t find answers to anywhere and people here seem very knowledgeable.
First, as I understand it, the primary driver in global warming is not the greenhouse gases themselves, but the various feedbacks that amplify the effect of the greenhouse gases themselves. Are these feedbacks determined empirically or theoretically or some combination? What are the relative contributions?
Second, since most of the warming is due to feedbacks and as we have seen, natural variations are in the short term larger than variations due to global warming, why havent’ the feedbacks been triggered by natural perturbations at some time in the past?
Thanks.
449, Gavin comment. Thank you. That helps in the appreciation of the paper that BPL linked to.
459, Brian. Thanks for the link.
Tom Graney asked:”Second, since most of the warming is due to feedbacks and as we have seen, natural variations are in the short term larger than variations due to global warming, why havent’ the feedbacks been triggered by natural perturbations at some time in the past?”
Feedbacks have operated in the past big time. For example, slight increases in solar insolation from orbital changes result in slight warming, which releases some CO2 and raises water vapor, which warms the planet some more, which releases some CO2 and raises water vapor, which raises temperatures, etc.
For your first question, in modern times the increase in warming from increased CO2 and resulting water vapor feedback are roughly equal.
[Freezingly:] Thank you, Gavin, I am aware that concentration is not the same as mass. I was under the impression that the OP thought CO2 had a different scale height from the rest of the atmosphere.
“First, as I understand it, the primary driver in global warming is not the greenhouse gases themselves, but the various feedbacks that amplify the effect of the greenhouse gases themselves. Are these feedbacks determined empirically or theoretically or some combination? What are the relative contributions?”
Read IPCC working group 1 report, http://www.ipcc.ch
Or google “how climate models work”
Note also that evidence for the sensivitiy of climate to CO2 does not depend on models. There is actual evidence, from paleoclimate, that shows if you double CO2, T goes up 3 degrees.
“Second, since most of the warming is due to feedbacks and as we have seen, natural variations are in the short term larger than variations due to global warming, why havent’ the feedbacks been triggered by natural perturbations at some time in the past?”
Ice ages? CO2 in the precambian period? The earth’s climate has been VERY different in the past.
What was the coal, before it was coal?
Gavin – you are losing credibility by not admitting that the facts, circumstances and aura of the emails looks bad – sorry….it’s not playing well with the intelligentsia that are not inside the game….this should not be in dispute with reasonable people – and it doesn’t hurt the general case for AGW, or mean that there is a huge conspiracy – but it’s pretty clear to most everyone who has looked at these things that a dangerous brew of politics and science has produced a bad result – and it needs to be accepted and fixed by the insiders, or the outsiders will fix it in a way that is not to your liking i’m afraid…and they will be justified.
[Response: ‘circumstances’ and ‘auras’ whipped up by the blogosphere may well be designed to look bad, but I try and actually keep track of what the truth is instead. Whether this ‘plays well’ among people that haven’t looked into it is not a determinant of anything much. – gavin]
I have a question about the CO2 lifetime (not particularly relevant to this or other current posts unfortunately).
David Archer and others have argued that “earlier cuts in emissions would have a greater effect in reducing climate change than comparable reductions made later.” This seems a logical conclusion for a time period that is short compared to the long lifetime of CO2.
However, Allan at al (Nature Climate Crunch) argue that it’s the total amount of emissions that matter, and that the resultant warming is not very strongly dependent on the trajectory of the emissions.
These statements seem inconsistent with each other at first sight, or is it due to the different timescales they’re looking at? I.e. for the final equilibrium warming it doesn’t matter when emissions are reduced, but for the intermittent (rate of) warming it does. Is that correct?
Unsettled science
“In the climate field, there are a number of issues which are no longer subject to fundamental debate in the community”
I’ll assume this is a very basic question as I am new to climatolgy.
I’m almost scared to ask it but after watching this video I have to ask it.
http://www.youtube.com/watch?v=F_G_-SdAN04&feature=player_embedded
What temperature record do we have of the last 100 yrs besides that of thermometers in Stephenson screens?
Gavin you said “[Response: Don’t get it. Why does repeating the correction for urban biases that is already in the GISTEMP analysis affect anything? And this has nothing to do with homogenisation issues either. – Gavin]
What I get is that this is raw unadjusted data and the rural sites show no trend over the last 100 yrs. This questions the axiom that temperatures have risen in the last 100yrs. I know you think this is settled hence my question. What temperature record do we have of the last 100 yrs besides that of thermometers in Stephenson screens?
[Response: ocean data, retreating glaciers, changes in phenology (timing of spring blooms, migrations etc.), boreholes… And the trend in the rural stations in CONUS is not zero in any case. – gavin]
A strong bout of natural cooling in 2008
http://www.agu.org/pubs/crossref/2009/2009GL041188.shtml
A precipitous drop in North American temperature in 2008, commingled with a decade-long fall in global mean temperatures, are generating opinions contrary to the inferences drawn from the science of climate change. We use an extensive suite of model simulations and appraise factors contributing to 2008 temperature conditions over North America. We demonstrate that the anthropogenic impact in 2008 was to warm the region’s temperatures, but that it was overwhelmed by a particularly strong bout of naturally-induced cooling resulting from the continent’s sensitivity to widespread coolness of the tropical and northeastern Pacific sea surface temperatures. The implication is that the pace of North American warming is likely to resume in coming years, and that climate is unlikely embarking upon a prolonged cooling.
Citation: Perlwitz, J., M. Hoerling, J. Eischeid, T. Xu, and A. Kumar (2009), A strong bout of natural cooling in 2008, Geophys. Res. Lett., 36, L23706, doi:10.1029/2009GL041188.
RE: Bart #459
Apologies if this isn’t responsive to your question or is poorly expressed, but maybe it will prompt someone else to do better.
I think the difference is whether one is considering the climate (or earth system) response – in which case it doesn’t much matter whether the CO2 is released sooner or later – or the efficacy in meeting policy objectives (in terms of total atmospheric CO2 or change in temperature) – in which case reducing emissions sooner is much more likely to succeed. In the latter context, there is indeed a “time value of carbon.”
See, for instance
Vaughan, Lenton and Shepherd. 2009. Climate change mitigation: trade-offs between delay and strength of action required. Climatic Change. Published online 15 April 2009. DOI 10.1007/s10584-009-9573-7
Abstract: Climate change mitigation via a reduction in the anthropogenic emissions of carbon dioxide (CO2) is the principal requirement for reducing global warming, its impacts, and the degree of adaptation required. We present a simple conceptual model of anthropogenic CO2 emissions to highlight the trade off between delay in commencing mitigation, and the strength of mitigation then required to meet specific
atmospheric CO2 stabilization targets. We calculate the effects of alternative emission profiles on atmospheric CO2 and global temperature change over a millennial timescale using a simple coupled carbon cycle-climate model. For example, if it takes 50 years to transform the energy sector and the maximum rate at which emissions can be reduced is −2.5% year−1, delaying action until 2020 would lead to stabilization at 540 ppm. A further 20 year delay would result in a stabilization level of 730 ppm,
and a delay until 2060 would mean stabilising at over 1,000 ppm. If stabilization targets are met through delayed action, combined with strong rates of mitigation, the emissions profiles result in transient peaks of atmospheric CO2 (and potentially temperature) that exceed the stabilization targets. Stabilization at 450 ppm requires maximum mitigation rates of −3% to −5% year−1, and when delay exceeds 2020,
transient peaks in excess of 550 ppm occur. Consequently tipping points for certain Earth system components may be transgressed. Avoiding dangerous climate change is more easily achievable if global mitigation action commences as soon as possible. Starting mitigation earlier is also more effective than acting more aggressively once mitigation has begun.
Re: Luke 380 and subsequent comments by others
The authors of the Nature study have responded with a letter, published in The Australian yesterday http://blogs.theaustralian.news.com.au/letters/index.php/theaustralian/comments/in_thrall_to_totalitarian_green_science/
Here it is:
IN his opinion piece (“Climate claims fail science test”, Commentary, 9/12) Michael Asten has misrepresented our recent research by suggesting that it casts doubt on the link between atmospheric carbon dioxide and global warming.
Our study, published in the journal Nature, is a reconstruction of atmospheric CO2 levels 33-35 million years ago when the ice cap first appeared on Antarctica. In the paper, we clearly state that the results are in line with expectations from climate model simulations and theory on how the global carbon cycle ought to respond to the growth of an ice cap over very long periods of time.
Asten says that climate after the ice cap grew was similar to the present day, despite higher levels of CO2. He ignores a vast amount of geological data to the contrary and our clear and fully referenced statement that the world at this time was warmer than today, with no evidence for sustained continental ice caps in the northern hemisphere, and possibly West Antarctica, until much later.
There is a general correspondence between periods of warmth in the past and reconstructed CO2 concentrations, but we caution against any attempt to derive a simple narrative linking CO2 and climate on these large timescales. This is because many other factors come in to play including other greenhouse gases, moving continents, shifting ocean currents, dramatic changes in ocean chemistry, vegetation, ice cover, sea level and variations in the Earth’s orbit around the sun.
Carbon dioxide levels are currently rising year-on-year at an alarming and geologically unprecedented rate. Nobody, to our knowledge, is seriously questioning this, or the sound physics that underpins the greenhouse effect.
We would like to take this opportunity to add our voices to the strong and steady message that the world scientific community is delivering to the Copenhagen negotiators—the greenhouse problem is real, imminent and potentially devastating for the planet, its life and human civilisation. Fortunately it is still not too late to avert the catastrophe.
Paul Pearson, Cardiff University
Gavin Foster, National Oceanographic Centre, Southampton
Bridget Wade, Texas A&M University
Any resemblance between http://www.huffingtonpost.com/david-horton/dui—denying-under-influ_b_389887.html and any persons living or dead on any thread on any blog anywhere in the world is purely a coincidence. Possibly.
“Second, since most of the warming is due to feedbacks and as we have seen, natural variations are in the short term larger than variations due to global warming, why havent’ the feedbacks been triggered by natural perturbations at some time in the past?”
Where is the evidence for your premise that “most of the warming is due to feedbacks”? Thus far, the feedback theory is an exercise in hand waving to explain away the inconvenient fact that in the past the rise in temperature preceded the rise in CO2 concentrations.
There is the very well developed discipline of System Identification that can detect the signature of such feedback mechanisms from empirical data. Positive feedback systems are characterized by complex-pole pairs that cause spectral peaking of the natural variation noise. No such peaking can be found in the Vostok data and in fact system analysis indicates the climate system is remarkably stable and dominated by regulatory (negative feedback) effect with a time constant on the order of 100 KA. This fact alone makes the climatologists’ claim that they can detect a centennial trend amongst the natural variation and huge regulatory reserve akin to the notion that one could discern the rise in sea level from spitting in the ocean.
I can’t be the only one who has done such a rudimentary analysis. The fact that no papers have been published indicates perhaps that the alarmists prefer to wave their hands and hope no one will notice.
Tom Graney, First, you must understand that the feedbacks we are talking about are in no way unique to CO2 or even greenhouse mechanisms. It is merely the recognition that when you add a watt of energy to the system the system will experience changes that amplify or diminish the thermal effect. For example, warmer temperatures mean more water vapor in the atmosphere, and water vapor is a greenhouse gas. Some of the feedbacks can be calculated analytically. Others, such as cloud effects are more uncertain. The net effect, which can be understood in terms of, for example, the CO2 sensitivity, is well constrained empirically. More than 10 separate lines of evidence that all favor a CO2 sensitivity of 3 degrees per doubling of CO2 concentration, and all of these rule out (at ~90% CL or better) a sensitivity of 2 degrees or less. In fact, if the current models are wrong, it’s far more likely that sensitivity is higher than 3 degrees per doubling rather than lower.
There are also potential feedbacks that could greatly increase warming, such as release of methane and CO2 from thawing permafrost. These are not considered in current warming estimates.
Gavin,
In your November 23 posting you said:
““Redefine the peer-reviewed literature!” . Nobody actually gets to do that, and both papers discussed in that comment – McKitrick and Michaels (2004) and Kalnay and Cai (2003) were both cited and discussed in Chapter 3 the IPCC AR4 report. As an aside, neither has stood the test of time.”
I can’t find any mention of those papers in that report, nor are the authors referenced at the end.
Perhaps I overlooked/misunderstood something. Would you be kind enough to give the page number(s)?
And please, can we all tone down the ugly language?
Thanks,
Paul Sinclair
Austin, Texas
“And please, can we all tone down the ugly language?
If by ugly you mean “hostile”, then you can take that up squarely with the side who has decided that accusing scientists of fraud, stealing private emails, sending hate mail, and now issuing death threats, is the way to get things done.
These are vicious people we’re dealing with, as is now abundantly clear.
Paul Sinclair: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf
Pages 244-245.
J Patterson, all you need is to shoot your phasers into the dilithium crystals, thereby realigning their positronic lattice to the warp engine manifold matrix…
Paul Sinclair quotes from the post by Gavin:
… then states:
Paul, they are referenced on the same page in the same column, at the beginning of separate paragraphs.
Please see:
… and:
Paul Sinclair 13 December 2009 at 12:09 PM
Chapter 2 maybe?
PS to my comment on paragraphs in ar4-wg1-chapter3.pdf above in response to Paul Sinclair…
It is “Chapter 3 Observations: Surface and Atmospheric Climate Change” available at:
IPCC Fourth Assessment Report (AR4)
Climate Change 2007: The Physical Science Basis
http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_wg1_report_the_physical_science_basis.htm
Paul Sinclair, the papers are discussed in section 3.2.2.2 on pp. 244-5 of the AR4 WG1 report, Chapter 3 “Observations: Surface and Atmospheric Climate Change” (big PDF). And referenced in the bibliography. Maybe you were looking at the synthesis report, or something?
J. Patterson (465) — Actually, it is not that stable. Try Ray Pierrehumbert’s
http://geosci.uchicago.edu/~rtp1/ClimateBook/ClimateBook.html
for starters.
J. Patterson: Thus far, the feedback theory is an exercise in hand waving to explain away the inconvenient fact that in the past the rise in temperature preceded the rise in CO2 concentrations.
BPL:
1. Feedbacks are empirically observed, especially the largest one, the water-vapor feedback.
2. Temperature does indeed precede CO2 in a natural deglaciation. It did not in the PETM, nor is it doing so now. For more depth, try here:
http://BartonPaulLevenson.com/Lag.html
J. patterson (465).”there is a very well developed discipline of System Identification that can detect the signature of such feedback mechanisms from empirical data.”
Can you please provide references to(preferably)peer reviewed literature, which details a relationship between the theory mentioned, to the theory and historical data regarding co-2 feed-back and temperature. I do not know of your background in the climatology field, and therefore I would appreciate other supporting information relating to your statements in this post. Thanks, Doug
A lot of “the science hasn’t settled debate” comes from the image the general public may have about climate data which is not released, confirmed in their view by statements like “to hide the decline”. The public opinion is that science has something to hide, and this amplifies the thought that something shouldn’t be told because it is not true. Deniers always want to read a confirmation. But even if it were true that data is hidden then it is usually harmless. Perhaps it helps to explain this with the following classroom experiment.
Suppose that I explained Ohm’s law in a classroom but that I refuse to disclose my data. Would that cause Ohm’s law to be invalid or my research be fraudulent or maybe simply wrong? What could you do to verify Ohm’s law? The answer is, you get a multimeter, a power supply and a potentiometer and you carry out the exercise to verify Ohm’s law yourself. Eventually also a skeptic will find the answer, or his critical neighbor will. Since everyone is able to do this experiment there is no further debate, because, the results are duplicable. Ohm’s law is therefor assumed to be valid and everybody is happy despite the fact that data is not disclosed.
With temperature reconstructions of the Earth’s past climate it is in essence the same discussion. There are independent methods, papers, etc etc. Garvin has a lot of useful links showing that people are pretty well in agreement here. I don’t mind the cheats like McIntyre in this debate, because, they have been proven wrong too often.
Yet unique is that the global warming deniers can make a lot of noise these days, and that they can create a virtual world where the general public is lured into into the idea that you have to pay more taxes and eventually that you maybe can’t drive in a car or fly in an airplane anymore.
Ernst, Do you require the data relating to the discovery of the Top quark as well? How about the observation of a Bose-Einstein condensate? Would you have any idea what to do with the data if you had it? Climate science has actually been out ahead of the curve as far as making the data public. Remember that the Internet has only been around for about 15 years as far as the public is concerned. Climate scientists have already released mountains of data, and what have the denialists done with it? Bupkis.
I would worry about evidence more than I would worry about whether every last scrap of data is available to every moron with a laptop.
J. Patterson: Thus far, the feedback theory is an exercise in hand waving to explain away the inconvenient fact that in the past the rise in temperature preceded the rise in CO2 concentrations.
BPL:
1. Feedbacks are empirically observed, especially the largest one, the water-vapor feedback.
How is this relevant? The issue at hand is the CO2 amplification factor, about which there is far more uncertainty than is being acknowledged here.
2. Temperature does indeed precede CO2 in a natural deglaciation.
It does so for the entirety of the Vostok time record.
It did not in the PETM,
Are you claiming CO2 caused the PETM?
nor is it doing so now. For more depth, try here:
Depth? Your reference is a poster child for the just-so story handing waving I referred to.
“D. Metcalfe”: Can you please provide references to(preferably)peer reviewed literature, which details a relationship between the theory mentioned, to the theory and historical data regarding co-2 feed-back and temperature.
Sys Id is a generic set of algorithms and analysis tools for building and/or verifying models of dynamic systems (including coupled non-linear systems). One would not write a paper one its relationship to climatology anymore than one would write about the relationship of statistical analysis to same. If your interested in the topic of System Identification in general, I suggest a google search.
I can find no peer reviewed journal papers on the application of these well known techniques to the study of climate dynamics, hence my closing remark.
“I do not know of your background in the climatology field, and therefore I would appreciate other supporting information relating to your statements in this post. Thanks, Doug”
I’m not a climatologists. My relevant background is in the development of algorithms for the rapid identification and equalization of communication channel dynamics under varying atmospheric and ionospheric conditions. I
Unsettled science appears floating as dross:
“Leading scientists, including a Nobel Prize-winner, have rounded on studies used by climate sceptics to show that global warming is a natural phenomenon connected with sunspots, rather than the result of the man-made emissions of carbon dioxide.
The researchers – all experts in climate or solar science – have told The Independent that the scientific evidence continually cited by sceptics to promote the idea of sunspots being the cause of global warming is deeply flawed.
Studies published in 1991 and 1998 claimed to establish a link between global temperatures and solar activity – sunspots – and continue to be cited by climate sceptics, including those who attended an “alternative” climate conference in Copenhagen last week.
However, problems with the data used to establish the correlation have been identified by other experts and the flaws are now widely accepted by the scientific community, even though the studies continue to be used to support the idea that global warming is “natural”.”
More:
http://www.independent.co.uk/environment/climate-change/sunspots-do-not-cause-climate-change-say-scientists-1839867.html
http://www.independent.co.uk/environment/climate-change/sun-sets-on-sceptics-case-against-climate-change-1839875.html
Variability of El Niño/Southern Oscillation activity at millennial timescales during the Holocene epoch
Christopher M. Moy, Geoffrey O. Seltzer, Donald T. Rodbell & David M. Anderson
http://www.nature.com/nature/journal/v420/n6912/full/nature01194.html
is short; I found the paper of definite interest regarding the persistence of ENSO but also its slow evolution.
J. Patterson, in particular just now, ought to take note of this work.
Hi, I’m wondering if anyone can tell me about climate researchers or departments who have focussed their efforts mainly on attempting to falsify the theory of anthropogenic global warming. Falsification is an inherent part of the scientific process, so it strikes me that I’ve heard very little about the role this process has played in climate modelling. The attempt to falsify is in itself always a valuable endeavour, as useful information is gained along the way, which often proves valuable in honing the theory. Many thanks, Catherine.
Um, regarding some of the ‘ugly language’ and strong feelings towards skeptics – you gotta understand that many skeptics feel very, very let down, deceived, and bitterly disappointed by what they see as ‘scientists’ who have sold out their fundamental principles for the sake of proving a point. Gentler skeptics will admit they don’t think the CRU was deliberately evil, just misled… but still, there are a lot of people around right now who are hurting because they feel what has happened has damaged science in general. Getting all hurt and bitter in return isn’t going to help anything. If the work that’s been done has merit, then the truth will win out at the end of the day, but to do that, the CRU folk and AGW proponents generally must must be willing to engage, many times if necessary and in detail, with those who dispute the science. Only time will work out these differences. Both sides claim they uphold the truth and both sides engage in politicised language and rhetorical tricks.
“In the climate field, there are a number of issues which are no longer subject to fundamental debate in the community. The existence of the greenhouse effect, the increase in CO2 (and other GHGs) over the last hundred years and its human cause, and the fact the planet warmed significantly over the 20th Century are not much in doubt. IPCC described these factors as ‘virtually certain’ or ‘unequivocal’. The attribution of the warming over the last 50 years to human activity is also pretty well established – that is ‘highly likely’ and the anticipation that further warming will continue as CO2 levels continue to rise is a well supported conclusion. To the extent that anyone has said that the scientific debate is over, this is what they are referring to. In answer to colloquial questions like “Is anthropogenic warming real?”, the answer is yes with high confidence.”
I have a couple of questions:
1) How can anthropogenic warming be considered highly likely when there is no control group against which to compare empirical data?
2) What percentage of the Earth’s atmosphere is CO2 ideally? Today?
3) Have CO2 levels ever been higher? Lower?
4) What percentage of the world’s CO2 output is anthropogenic? Natural?
5) Is there any possibility that these changes are just the Earth and the solar system going through natural fluctuations?
Any answers to these questions would be greatly appreciated — I am writing a paper on the global warming debate in which I am supposed to argue BOTH sides — Thanks!
Gavin: #438
“The full email is a much clearer read than McIntyre’s cherry-picking. – gavin]”
Okay, so I’m reading the email to see how the meaning of “hide the decline” is changed by taking the whole context. I haven’t discovered that yet, but I’m still reading. In the meantime, I thought that this section by Briffa was more than a little revealing. Thanks for the link.
Briffa:
“>I know there is pressure to present a
>nice tidy story as regards ‘apparent unprecedented warming in a thousand
>years or more in the proxy data’ but in reality the situation is not quite
>so simple. We don’t have a lot of proxies that come right up to date and
>those that do (at least a significant number of tree proxies ) some
>unexpected changes in response that do not match the recent warming. I do
>not think it wise that this issue be ignored in the chapter.
> For the record, I do believe that the proxy data do show unusually
>warm conditions in recent decades. I am not sure that this unusual warming
>is so clear in the summer responsive data. I believe that the recent warmth
>was probably matched about 1000 years ago. I do not believe that global
>mean annual temperatures have simply cooled progressively over thousands of
>years as Mike appears to and I contend that that there is strong evidence
>for major changes in climate over the Holocene (not Milankovich) that
>require explanation and that could represent part of the current or future
>background variability of our climate. ”
I also noted that in your (Gavin’s) debate with Christy you seem to have given up on the “unprecedented” nature of 20th Century warming somewhat. Instead, choosing to drive the simpler idea that it is warming and that it is caused by man made CO2.
Gavin
I do have one more question.
lets say that a “Little Ice Age Event” is a period when the Earth’s climate enters a period of cooling (strong enough to cause severe Winter freezing of a Thames like river), remains in this phase for about 100 years and then enters a period of strong warming. Whatever the cause of this event it could not be attributed to man’s industrial emissions.
Do the climate computer models produce these events and if so, is the frequency at which they appear roughly consistent across the different models.
Hank: #461
“We demonstrate that the anthropogenic impact in 2008 was to warm the region’s temperatures, but that it was overwhelmed by a particularly strong bout of naturally-induced cooling resulting from the continent’s sensitivity to widespread coolness of the tropical and northeastern Pacific sea surface temperatures. The implication is that the pace of North American warming is likely to resume in coming years, and that climate is unlikely embarking upon a prolonged cooling.”
2008 was cool because of a La Nina. Fair enough. 2009 will be warm because of an El Nino. But think about this Hank. In the 11 years since the 1998 El Nino we should have added about .22C to the base temperature. So 2009 should be working off a higher platform with it’s El Nino that 1998 was. But it still can’t exceed 1998. All in all, the two individual years don’t matter that much. The trend line from 1998 to 2008 was slightly down. The trend line from 1998 to 2009 will probably be slightly up. But in both cases, they are still close to flat – and in both cases they are not anywhere close to the .22C rise that we would expect to see in 11 years. Please don’t just give me another link, Hank. And please don’t talk about other elements of natural variation if you cannot identify them. I won’t buy the argument that the time period is too short because of natural variation unless you can tell me what natural variation overrode CO2.
“I can find no peer reviewed journal papers on the application of these well known techniques to the study of climate dynamics, hence my closing remark.”
Ah, you’re trying Jedi tricks again!
“These are not the answers you’re looking for…”
J. Patterson, What you are failing to take into account is the fact that we have very good measurements of temperature over the past ~130 years, while resolution is more limited in the ice core data. It is rather doubtful that Sys. Id. could discern the feedbacks given the noise in the data. There are about 10 separate lines of evidence constraining CO2 sensitivity. All favor a value around 3 degrees per doubling. All preclude a sensitivity below 2 degrees per doubling. Thus, while there are some uncertainties in individual feedbacks, the net result is well measured.
JP: the feedback theory is an exercise in hand waving to explain away the inconvenient fact that in the past the rise in temperature preceded the rise in CO2 concentrations.
BPL:
1. Feedbacks are empirically observed, especially the largest one, the water-vapor feedback.
How is this relevant?
Because “empirically observed” is not compatible with “hand waving.”
BPL: 2. Temperature does indeed precede CO2 in a natural deglaciation…nor is it doing so now. For more depth, try here:
JP: Depth? Your reference is a poster child for the just-so story handing waving I referred to.
BPL: Can’t you read? Ln CO2 is highly correlated to temperatures IN THE SAME YEAR for 1880-2007. That’s hardly an 800-year time lag, now is it? And in a natural deglaciation, the CO2 bloody well comes from the ocean giving it up when its solubility changes. And now it’s bloody well coming from fossil fuels, as we know very well from the radioisotope signature. Your whole “temperature precedes CO2” thing is WRONG. That’s not hand-waving, pal, that’s reality. Deal with it.
scarlson – I’m not going to answer your questions, but you can answer them yourself. Click “Start here” at the top of the page. Read that, then if you have questions, come back.
Catherine Jameson – What type of engagement are you looking for that RC doesn’t provide?
Did it occur to you that the folks at CRU did nothing wrong?
Your question of ‘falisfy’ is a weird one. I’m not aware of any scientist, in any field, who works on ‘falsifying’ other scientists work. Can you suggest anyone who is trying to ‘falisfy’ the HIV=AIDS issue, or gravity, or Einstein?
What we do is attempt to improve our understanding of our field. This means testing our assumptions. So when a climate scientist takes new data, and makes a new recontruction (or model) (s)he is trying not to support, or falsify, an idea, but test it.
All models test our understanding of climate. All reconstructions do. If the model or reconstruction disagrees with current theory, either the experiement is wrong, or the theory is wrong. You then work out why.
Finally, do you have any idea how much a climate model that WORKED and could disprove climate change would be worth? Millions? Billions? A trillion?
Comment by scarlson — 14 December 2009 @ 1:22 AM
None of those are questions without answers you can find on your own with a few minutes of effort. They’re all extremely basic. To succeed in your academic endeavor you’ll need to figure out how to do simple research, so best to practice that skill now. Here’s a good place to start, if you want to practice using AGW as monkey-bars:
http://www.aip.org/history/climate/
scarlson:
1) How can anthropogenic warming be considered highly likely when there is no control group against which to compare empirical data?
BPL: Because the physical theory makes predictions which observations have borne out. Many different climates have existed and we have good data on a lot of them; any one can be your reference point.
2) What percentage of the Earth’s atmosphere is CO2 ideally? Today?
BPL: There is no “ideal” level. However, human agriculture and the human economy all arose when CO2 was about 280 parts per million by volume. Today it is 388 ppmv.
3) Have CO2 levels ever been higher? Lower?
BPL: They were much higher early in Earth’s history, which was crucial to life getting started. The most recent low point was 180 ppmv at the last glacial maximum, 18,000 years ago.
4) What percentage of the world’s CO2 output is anthropogenic? Natural?
BPL: Very little is anthropogenic, but the natural sources are roughly in balance with the natural sinks. The anthropogenic input is what causes the overflow. As a result, 28% of the CO2 currently in the air around us is artificial.
5) Is there any possibility that these changes are just the Earth and the solar system going through natural fluctuations?
BPL: Possible but incredibly unlikely. For more on the sun, check here:
http://BartonPaulLevenson.com/Sun.html
phil c (488) — Easy enough to reproduce LIA by a combination of volcanoes and various solar phenomena. However, do not dismiss potential anthropogenic influences as well:
http://en.wikipedia.org/wiki/Little_Ice_Age#Anthropogenic_influences
> Tilo Reber
> … don’t talk about other elements of natural
> variation if you cannot identify them. I won’t buy
> the argument that the time period is too short because
> of natural variation unless you can tell me what
> natural variation overrode CO2.
Almost all of them, of course; you know this. It’s a weak signal — but it’s a steadily increasing one, along with a great many that go up and down rather than change steadily.
For any youngster just coming to the subject though:
the greenhouse signal is a very small one that takes decades to emerge from the background noise.
http://www.jstor.org/pss/1515382
http://www.springerlink.com/content/m624g15430941707/
Look at the change from summer to winter or even from day to day; most natural variables are far stronger than the greenhouse effect from CO2 increase.
But the natural variables don’t change steadily in one direction on a time scale of decades; something like Milankovich forcing or changes in the solar cycle are far slower; seasonal changes are far faster. But they average out, while anthropogenic greenhouse gas steadily increases.
http://www.seed.slb.com/subcontent.aspx?id=4120
http://web.mit.edu/jsterman/www/Understanding_public.html
Black Soot Might Be Main Culprit of Melting Himalayas:
http://www.livescience.com/environment/091214-black-carbon-himalaya-glacier.html
Hank: #497
“Almost all of them, of course;”
Thanks for the hand waving Hank. You have confirmed what I said. Neither you nor anyone else among the warmers knows what elements of natural variation have caused the flat trend since 1998. That is exactly why it’s significant. Telling the AGW signature from the background noise over the course of a decade should be very posssible if you know what those elements are and what they have done during that decade. You can say ENSO or PDO produces a larger signal than CO2, but then you would have to show that ENSO or PDO have produced a larger signal over the past decade. Since they didn’t – indeed, since there were more El Nino’s than La Ninas and since ENSO compensated data sets don’t help you, you can’t blame it on that element of natural variation. Same applies to all the other elements of natural variation. You only have two possible options Hank, either our flat trend is flat because there are elements of natuaral variation at work that we don’t understand, or it’s flat because climate sensitivity is much lower than the IPCC claims.
Nonsense, Tilo, and you’ve been round this circle before. I’m an ordinary reader on a blog, and the fact that I can’t assign weights to all natural forcings proves nothing except that I’m not everyone you need to talk to. Expand your horizons, read something from people who actually know what they’re talking about here. I test what I read to decide who I can trust.
You, I can’t, you just proclaim what you believe but you don’t do the arithmetic.
Simple high school explanation: we know natural variability from history and as with _any_ statistical question, once we know how variable the natural world is, we can find out how many samples (in the case of annual temperatures, how many years) we need before we can say we have a probability of knowing whether there is a trend different from zero.
Ten years ain’t in the ballpark, dude. All I need to know is how variable conditions have been in the past and a little from Statistics 101. You don’t have it.
Reading helps. I don’t know anything else to suggest, other than waiting. Oh, you might make a large bet on what you believe; try Stoat, I think he’s keeping track and may know someone who would give you the odds you believe you deserve. I’d like to watch that.
http://home.badc.rl.ac.uk/lawrence/blog/2005/04/08/another_excellent_summary_of_climate_modelling
If you don’t read the work all I can suggest is you look at the pictures. Reading will help you more tho’.
Stoat: http://scienceblogs.com/stoat/2007/05/the_significance_of_5_year_tre.php
Five-, ten-, and fifteen-year trends:
http://scienceblogs.com/stoat/upload/2007/05/5-year-trends.png
Atmoz: http://atmoz.org/blog/2008/01/29/on-the-insignificance-of-a-5-year-temperature-trend/
Thirteen-year trends:
http://atmoz.org/img/avg_length13.jpg
Thirty-year trends:
http://atmoz.org/img/avg_length30.jpg
More:
http://thingsbreak.wordpress.com/2009/09/10/of-moles-and-whacking-climate-models-didnt-predict-this-lack-of-warming/
http://moregrumbinescience.blogspot.com/2009/07/what-cooling-trend.html
“It is yet another reminder that short term variations, namely weather, can be large. It isn’t climate.”