Global Warming and Chaos Theory

[McHeathen]

There has been much controversy concerning Global Warming: sun spot activity, only heat radiation at 15 microns being trapped by CO2, vast amounts of greenhouse gases going intot he atmosphere from exploding volcanos and the general cyclical nature of climate change have attempted to explain the insignificance on human interaction on the environment as having a significant effect on GM.

I came across documentary which made reference to how 'Chaos Theory' explained the significant effect of human interaction on climate change. Can someone give some elaboration on this?

 

[Bored Wombat]

There has been much controversy concerning Global Warming: sun spot activity, only heat radiation at 15 microns being trapped by CO2, vast amounts of greenhouse gases going into the atmosphere from exploding volcanoes and the general cyclical nature of climate change have attempted to explain the insignificance on human interaction on the environment as having a significant effect on GM.

I came across documentary which made reference to how 'Chaos Theory' explained the significant effect of human interaction on climate change. Can someone give some elaboration on this?

I don't think that there has been much controversy concerning global warming from within the scientific community.

Sunspot activity does affect the climate but variations in solar irradiance are probably less than 10% of the change in radiative forcing due to the anthropogenic part of the greenhouse effect.

There are a few absorption bands of CO₂ that make it a greenhouse gas.

Volcanoes produce a very small fraction of the CO₂ compared to anthropogenic sources.

The since the middle of last century this warming is mostly (or entirely) anthropogenic. It is not cyclic.


However, I imagine that chaos theory wrt climate change is because the climate system exhibits sensitive dependence on initial condition. This means that if someone in Australia paints their house roof dark green, then the thermal eddies created there can have a significant effect on the Atlantic Hurricanes two years later. Impossible to predict, and although it probably is a change in climate, it is not really "climate change" by which is generally meant the effect on climate of anthropogenic global warming and its effects.

 

[Andre]

I don't think that there has been much controversy concerning global warming from within the scientific community.

And I don't think that this is a very accurate representation of the reality. For instance the Assessment Reports of the IPCC have not been peer reviewed in the classical way, because the editors were free to accept or reject comments from the reviewers. The summaries for policy makers was not reviewed by the specialists but only by government representatives and showed a somewhat different picture than the chapters.

Therefore the specialists decided to write their own Independent Summary for Policy Makers, which was reviewed by peers:

http://www.uoguelph.ca/~rmckitri/research/ispm.html

Having somewhat http://www.uoguelph.ca/~rmckitri/research/ISPM.pdf than the general party lines:

The Earth’s climate is an extremely complex system and we must not understate the difficulties involved in analyzing it. Despite the many data limitations and uncertainties, knowledge of the climate system continues to advance based on improved and expanding data sets and improved understanding of meteorological and oceanographic mechanisms.

The climate in most places has undergone minor changes over the past 200 years, and the land-based surface temperature record of the past 100 years exhibits warming trends in many places. Measurement problems, including uneven sampling, missing data and local land-use changes, make interpretation of these trends difficult. Other, more stable data sets, such as satellite, radiosonde and ocean temperatures yield smaller warming trends. The actual climate change in many locations has been relatively small and within the range of known natural variability. There is no compelling evidence that dangerous or unprecedented changes are underway.

The available data over the past century can be interpreted within the framework of a variety of hypotheses as to cause and mechanisms for the measured changes. The hypothesis that greenhouse gas emissions have produced or are capable of producing a significant warming of the Earth’s climate since the start of the industrial era is credible, and merits continued attention. However, the hypothesis cannot be proven by formal theoretical arguments, and the available data allow the hypothesis to be credibly disputed.

Arguments for the hypothesis rely on computer simulations, which can never be decisive as supporting evidence. The computer models in use are not, by necessity, direct calculations of all basic physics but rely upon empirical approximations for many of the smaller scale processes of the oceans and atmosphere. They are tuned to produce a credible simulation of current global climate statistics, but this does not guarantee reliability in future climate regimes. And there are enough degrees of freedom in tunable models that simulations cannot serve as supporting evidence for anyone tuning scheme, such as that associated with a strong effect from greenhouse gases.

There is no evidence provided by the IPCC in its Fourth Assessment Report that the uncertainty can be formally resolved from first principles, statistical hypothesis testing or modeling exercises. Consequently, there will remain an unavoidable element of uncertainty as to the extent that humans are contributing to future climate change, and indeed whether or not such change is a good or bad thing.

 

[Bored Wombat]

And I don't think that this is a very accurate representation of the reality.

On the other hand, in the scientific literature there is very little denialism.

The American Meteorological Society (6), the American Geophysical Union (7), and the American Association for the Advancement of Science (AAAS) all have issued statements in recent years concluding that the evidence for human modification of climate is compelling (8).

The drafting of such reports and statements involves many opportunities for comment, criticism, and revision, and it is not likely that they would diverge greatly from the opinions of the societies' members. Nevertheless, they might downplay legitimate dissenting opinions. That hypothesis was tested by analyzing 928 abstracts, published in refereed scientific journals between 1993 and 2003, and listed in the ISI database with the keywords "climate change" (9).

The 928 papers were divided into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, paleoclimate analysis, and rejection of the consensus position. Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position. (http://www.sciencemag.org/cgi/content/full/306/5702/1686" , Oreskes, Science (2004)

Actually there has been a comprehensive list of scientific societies of international standing, including the Joint Science Academies of Australia, Belgium, Brazil, Canada, the Caribbean, China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, Mexico, New Zealand, Sweden, and the United Kingdom.

Plus:
International Council of Academies of Engineering and Technological Sciences
European Academy of Sciences and Arts
Network of African Science Academies
National Research Council (US)
European Science Foundation
American Association for the Advancement of Science
Federation of American Scientists
World Meteorological Organization
American Meteorological Society
Royal Meteorological Society (UK)
Australian Meteorological and Oceanographic Society
Canadian Meteorological and Oceanographic Society
Canadian Foundation for Climate and Atmospheric Sciences
International Union for Quaternary Research
American Quaternary Association
Stratigraphy Commission of the Geological Society of London
International Union of Geodesy and Geophysics
International Union of Geological Sciences
European Geosciences Union
Canadian Federation of Earth Sciences
Geological Society of America
American Geophysical Union
American Astronomical Society
American Institute of Physics
American Physical Society
American Chemical Society
Engineers Australia (The Institution of Engineers Australia)
Federal Climate Change Science Program (US)
American Statistical Association

And as with the published papers:

With the July 2007 release of the revised statement by the American Association of Petroleum Geologists, no remaining scientific body of national or international standing is known to reject the basic findings of human influence on recent climate.

(from http://en.wikipedia.org/wiki/Scient...hange#Statements_by_dissenting_organizations")

For instance the Assessment Reports of the IPCC have not been peer reviewed in the classical way, because the editors were free to accept or reject comments from the reviewers.

That's been true of the last two assessment reports ... a concession made to time.
The first two the wording was slogged out at open meetings, with S Fred Singer standing up in the public gallery at every sentence and giving a long speech that everyone there knew was rubbish. (Presumably including himself).

The summaries for policy makers was not reviewed by the specialists but only by government representatives...

That's not quite true. The second draft is the one that the government representatives get to review. By that time is has already been reviewed reasonably exhaustively by specialists.

...and showed a somewhat different picture than the chapters.

However that is true. Government delegations always attempt to water down the danger, and the necessity for action. The most vociferous government delegations at the IPCC have traditionally been USA, China, Saudi Arabia and Kuwait. The worlds biggest consumer of fossil fuels per capita, the world's biggest consumer of fossil fuels, the world's biggest exporter of fossil fuels, and another economy dependent fully on the export of fossil fuels.

And so there is a valid criticism of the IPCC that the reports are too weak. And it is true that anything that is not very clearly true, and with all the research coming down with similar findings, are generally left out at the political review stage. Or not included because of the awareness that they will be chucked by the political review.

But as long as the are read with the understanding that they describe a best case scenario, the IPCC reports are informative to the intended audience ... laymen and politicians. Experts already know from the published research what is going on, and that there is little doubt.

Therefore the specialists decided to write their own Independent Summary for Policy Makers, which was reviewed by peers:

http://www.uoguelph.ca/~rmckitri/research/ispm.html

Ross M^cKitrick is an economist with known contrarian views on Global Warming, and a particularly enduring bee in his bonnet about northern hemisphere temperature reconstructions.

If he and nine of hid cronies wrote a document to challenge the one written by the IPCC's hundreds of authors and thousands of reviewers, I am not surprised that it has received less attention than the IPCC's one.

 

[LURCH]

In Chaos Therory, the Butterfly Effect states that very small intputs to a system can have disproportionately large effects. This is a way of trying to explain how the tiny influence of man can change the enitre atmosphere of Earth.

BTW; most of the surveys I've seen show the scientific community split about 60/40.

 

[Bored Wombat]

BTW; most of the surveys I've seen show the scientific community split about 60/40.

The denialist community are pretty effective at stacking surveys, especially after the damage to their credibility that the Oreskes literature review made plain.

If the split is over whether the current warming is likely to be mostly anthropogenic, and the scientific community is the climate science community, if the split is not about 99.9/0.1, then there's a selection bias, or a crap survey bias.

Because that's about the proportions of the published work.

And there's no disagreement from scientific organisations of any standing.

 

[Evo]

\And there's no disagreement from scientific organisations of any standing.

WRONG.

I suggest you read the EPA's official stance on Climate Change.

The official US EPA stance on what "is likely" is

In short, a growing number of scientific analyses indicate, but cannot prove, that rising levels of greenhouse gases in the atmosphere are contributing to climate change (as theory predicts).

http://www.epa.gov/climatechange/science/stateofknowledge.html

Also, I hope that you are aware that the IPCC hid the first part of their "report" from the public. The final report was not a consensus and they blocked any scientist that questioned what they were doing or provided evidence to the contrary.

IPCC Fourth Assessment Report Papers: Working Group I, The Physical Science Basis of Climate Change, 2005-2007; Expert Review Comments on First-Order Draft, Chapter 1. ESPP IPCCAR4WG1, which was previously withheld from the public until they were sued for the information under the "Freedom of Information Act".

The previously withheld report can be viewed here - http://pds.lib.harvard.edu/pds/view/7794905?n=2&imagesize=1200&jp2Res=.25 Where you can see how the IPCC "picked" the data they wished to present.

If you want to read some good posts on Climate Change, I suggest you search on Vanesch's posts and read them and you can respond to them here. If you don't, I will be glad to post them all here for you.

 

[vanesch]

The denialist community are pretty effective at stacking surveys, especially after the damage to their credibility that the Oreskes literature review made plain.

There are two kinds of "denialists": there are those who think that they can prove that there is no AGW, and then there are those that think that the scientific certainty displayed about AGW is exaggerated as of now. I belong to the second category, because I adhere to Feynman's statement concerning scientific research (paraphrased quote): "If you don't do everything which is in your power to prove yourself wrong, if you don't take every idea that could show you wrong seriously, then you are fooling yourself in science".

Well, if it does "damage to your credibility" to try to point out some weak points in the argument (and believe me, there are several of them!), then you are infringing on Feynman's statement.

Now, I know that the typical answer to that one is: yes, but someone who questions, say, relativity, or Newtonian mechanics, that's a crackpot, no ? Or someone questioning evolution, that's a religious fool, no ? That is because theories like relativity or Newtonian mechanics or evolution have a huge amount of unquestionable data behind them. You can take down tens or hundreds of those, and you still have solid proof, gathered over time. This is simply not (yet) true for the scientific case of AGW. There are elements, true. Each of those elements has however, some weakness to it. It is not overwhelming. It takes time to turn a speculative theory in a scientific certainty, and during this time, one should adhere to Feynman's advice.
The "solid AGW proof" of a few years ago turned out to have to be modified in such a way that it lost its convincing power (say, hockeystick, say, temperature/CO2 delay in paleodata,...). Refusing to take Feynman's advice, refusing to consider seriously the questioning of the solidity of the proof (you say it yourself, 99,9% of publications are not critical towards the AGW theory) at this point, is falling into the trap Feynman is pointing out, and is btw a sociological phenomenon known as groupthink. It happened in other domains (say, string theory :-).

Of course, nature doesn't care about how people do their science. AGW could well be there. I'm only pointing out that the scientific attitude towards it isn't healthy. One has the idea that one is "scientific" if one endorses the credo, and that one "damages one's credibility" if one asks critical questions. Once this happens, one has left the domain of scientific inquiry, and one is entering the domain of "building a case". I really wonder whether most climate scientists pushing AGW are "trying to prove themselves wrong" or are rather trying to "prove AGW".

And there's no disagreement from scientific organisations of any standing.

That's exactly what Feynman warned about.

 

[Bored Wombat]

WRONG.

I suggest you read the EPA's official stance on Climate Change.

The official US EPA stance on what "is likely" is

http://www.epa.gov/climatechange/science/stateofknowledge.html

No, that's exactly what I was saying, only a bit stronger.

They say that it is very likely that "Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations".

I know that it is not certain that most of the warming is anthropogenic, but they the EPA does say that it is certain that CO2 is a greenhouse gas, and that it's concentrations have been increased by human activity.

The only question that remains is what is the climate sensitivity to a rise in CO2 from 280ppm to 385ppm?

Well to a doubling it is about 3°C, so it's about 1.4°C for that rise. It may be a lot less, but there is a greater chance that it is a lot more. (If you look at the posterior probability density function for climate sensitivity from this paper: http://www.climate.unibe.ch/~stocker/papers/tomassini07jc1.pdf)

I think even outside minimal estimates of climates sensitivity are 1.5°C per doubling, which is still 0.7°C, which is still most of the warming, but it may not yet be all manifest, so possibly half of the warming is natural. We are talking not very likely though.

Also, I hope that you are aware that the IPCC hid the first part of their "report" from the public. The final report was not a consensus and they blocked any scientist that questioned what they were doing or provided evidence to the contrary.

IPCC Fourth Assessment Report Papers: Working Group I, The Physical Science Basis of Climate Change, 2005-2007; Expert Review Comments on First-Order Draft, Chapter 1. ESPP IPCCAR4WG1, which was previously withheld from the public until they were sued for the information under the "Freedom of Information Act".

The previously withheld report can be viewed here - http://pds.lib.harvard.edu/pds/view/7794905?n=2&imagesize=1200&jp2Res=.25 Where you can see how the IPCC "picked" the data they wished to present.

If you want to read some good posts on Climate Change, I suggest you search on Vanesch's posts and read them and you can respond to them here. If you don't, I will be glad to post them all here for you.

A perusal of the first few pages of comments and responses didn't indicate a bias to me. Did it to you?

It looks as though the IPCC position could have been much stronger, but for space constraints. The first comment in particular, that it should be included that we are returning the CO2 levels to ones that occurred when there was no ice sheet on Antarctica would have been pretty hard hitting in some quarters.

 

[Bored Wombat]

I belong to the second category, because I adhere to Feynman's statement concerning scientific research (paraphrased quote): "If you don't do everything which is in your power to prove yourself wrong, if you don't take every idea that could show you wrong seriously, then you are fooling yourself in science".

There are a lot more than one climatologist in the world. Even if there are a few who you claim are "fooling themselves in science", then there are plenty who would happliy take a Nobel prise by showing that the greenhouse effect doesn't actually work or that the warming that is temporally and spatially distributed in a way that is highly suggestive of the greenhouse effect, is from some other source.

Well, if it does "damage to your credibility" to try to point out some weak points in the argument (and believe me, there are several of them!), then you are infringing on Feynman's statement.

The "solid AGW proof" of a few years ago turned out to have to be modified in such a way that it lost its convincing power (say, hockeystick, say, temperature/CO2 delay in paleodata,...).

The impression one gets from the IPCC reports is that the case for AGW is in fact much stronger than it was in the late 90s.

And your two examples make me wonder what you've been reading. Not peer reviewed scholarly research, I suspect.

There have been a dozen northern hemisphere temperature reconstructions since Mann et al. 1998. And they are all "hockey sticks":

(from figure 6.10 of the IPCC 2007 working group I report).

The temperature/CO2 delay in paleodata is not at all problematic for AGW. It is known that the ice ages are regular, so they had to be set off by Malankovic cycles, or at least something regular. That an ice age gives way rapidly to a interglacial shows that CO2 is positively feeding back into the global temperature.

In fact careful analysis of paleoclimatic reconstructions of temperature and CO₂ concentrations lead to historical climate sensitivity estimates to a doubling of CO₂ not unlike current estimates. (which shows how much the behaviour is in line with expectations). Here are four examples of such papers off the top of my head; I'm sure a full literature review would confirm that paeloclimatic reconstructions are not problematic to AGW.

1) Efficiently[/PLAIN] Constraining Climate Sensitivity with Ensembles
of Paleoclimate Simulations Annan et al. SOLA (2005)
We attempt to validate the resulting
ensembles against out-of-sample data by comparing
their hindcasts of the Last Glacial Maximum (LGM) to
paleoclimate proxy data, and demonstrate through this
that our ensembles of simulations are probably biased
towards too high a sensitivity. Within the framework of
our single-model ensemble experiment, we show that
climate sensitivity of much greater than 6°C is hard to
reconcile with the paleoclimate record, and that of
greater than 8°C seems virtually impossible. Our
estimate for the most likely climate sensitivity is in the
region of 4.5°C.

2) Climate sensitivity estimated from ensemble simulations of glacial climate Schneider von Deimling et al. Climate Dynamics (2006)
Based on our inferred close
relationship between past and future temperature evolution,
our study suggests that paleo-climatic data can
help to reduce uncertainty in future climate projections.
Our inferred uncertainty range for climate sensitivity,
constrained by paleo-data, is 1.2–4.3°C and thus almost
identical to the IPCC estimate.

3) http://www.usclivar.org/Pubs/Hegerl042006.pdf Hegerl et al. Nature (2006)
Here we demonstrate that such
observational estimates of climate sensitivity can be tightened if
reconstructions of Northern Hemisphere temperature over the
past several centuries are considered. We use large-ensemble
energy balance modelling and simulate the temperature
response to past solar, volcanic and greenhouse gas forcing to
determine which climate sensitivities yield simulations that are
in agreement with proxy reconstructions. After accounting for
the uncertainty in reconstructions and estimates of past external
forcing, we find an independent estimate of climate sensitivity
that is very similar to those from instrumental data. If the latter
are combined with the result from all proxy reconstructions,
then the 5–95 per cent range shrinks to 1.5–6.2 K, thus substantially
reducing the probability of very high climate
sensitivity.

4) Climate sensitivity constrained by CO₂ concentrations over the past 420 million years Royer et al. Nature (2007)
We conclude that a climate sensitivity greater than
1.5 6C has probably been a robust feature of the Earth’s climate
system over the past 420 million years, regardless of temporal
scaling.

I'm only pointing out that the scientific attitude towards it isn't healthy. One has the idea that one is "scientific" if one endorses the credo, and that one "damages one's credibility" if one asks critical questions.

I don't see that that is happening. Investigations into climate sensitivity are common, follow a wide range to methods, and estimates way outside the accepted range have been published in high profile journals.

The fact that CO2 is a greenhouse gas and that human activity has increased its concentration are not questioned, but there are known.

 

[vanesch]

There have been a dozen northern hemisphere temperature reconstructions since Mann et al. 1998. And they are all "hockey sticks":

(from figure 6.10 of the IPCC 2007 working group I report).

Let us concentrate exactly (we're using indeed the same data :-) on this "hockey stick".

Compare it to the initial hockey stick on p 3 of
http://www.ipcc.ch/pdf/climate-changes-2001/scientific-basis/scientific-spm-en.pdf

the summary for policy makers in 2001.

Now, admit that there is a world of difference in the convincing power that we are *on an exceptional and dramatic temperature rise* which was the aim of that plot (with well-choosen coloring too) in the last century - a rise that was OBVIOUSLY an order of magnitude larger than what had happened in the last 1000 year.

When you look at the data of the proxies in the 2007 plot, no such *obvious* dramatic rise is present. Nor the values, nor the rise is an order of magnitude above what "seems normal". If this plot had been there in the 2001 report, it wouldn't have alarmed many people. I know that there has been a statistical analysis (you use "torturing the data until they confess" if the data aren't obviously indicating what you want - I know this, I do this sometimes too) that shows that the null hypothesis "the rise in the last 100 years is not greater than any rise in the previous 1000 years" can be rejected with a limited confidence, but admit that it is far from being as dramatic and obvious as it was in the "proof beyond doubt" in the 2001 report.
There is another error in the presentation of the 2007 plot. That is the visual confusion (using well-chosen coloring) of the proxy data and the actual measurements. Clearly, the proxy data are not 100% the same as the actual measurements (the solid black curve doesn't coincide perfectly with the proxies). That means that there is a dynamical system in between both, which can be for instance, a low pass filter. Well, you shouldn't compare data with different dynamical properties if the aim is to show a difference in dynamics (rise in this case). You shouldn't compare actual measurements which show a quick rise, with proxies which don't show such a quick rise, not now, and probably not in the past. Because if those proxies temper quick rise NOW, (low pass filtering), then they might have done so too in the past. So you cannot conclude then that the rise is faster now than back then.

Even better: shift the instrument data and the smooth grey curve back about 1000 years. You'd find about equal agreement. Was there an accute climate catastrophe around the year 1000 ?

Now, tell me, where is this critical analysis present in the current report ?

Leave away the current data (which are not the same as the proxies), and show only the proxies. Do you think that this still has the "hockey stick" conviction power ? You only see a smooth rising before 1000 AD, then a dip and indeed a slightly stronger rise in the last century. NOTHING TO DO with the dramatic effect displayed in the 2001 report. Where is the scientific honesty here ?

 

[Andre]

Let us concentrate exactly (we're using indeed the same data :-) on this "hockey stick".

Important is the observation that the blade of these hockeystick is glued upon it and that the proxies are not following which basically already refutes the robustness of these proxies.

But there is more, Mann et al 2008 admit that the adbundantly used and recycled tree ring proxies are basically flawed by showing the difference in skill in fig 2:

See also here the glued on blade, not following the proxies (still containing tree rings) and hence refuting the same.

See also that the CRU temperatures is a distinct outlier, temperatures were not al all through the roof at the end of the former century; on the contrary.

This is what it should have looked like:

So indeed one might challenge scientific honesty.

 

[vanesch]

The fact that CO2 is a greenhouse gas and that human activity has increased its concentration are not questioned, but there are known.

Well, again, there is no tight proof (although there is suggestive evidence) for this. What is usually taken as the evidence that the rise in CO2 is human-caused ?

1) there is the correlation between the human consumption of fossil fuels and of its concentration in the atmosphere

2) there is the correlation between the decrease of oxygen in the atmosphere and the rise in CO2

3) there is the isotopic composition of CO2 in the atmosphere, which shows that it has a rising component that most probably comes from fossil fuels (lower C-14 content).

However, although this is of course suggestive evidence, this is no proof at all. In order to show this, let us take on a purely imaginary situation. Imagine that the cause-effect relation is different: that a rise in temperature CAUSES a rise in equilibrium atmospheric CO2. I'm not saying that this is the case, or that I have the slightest bit of evidence for this. I'm just indicating a working hypothesis to show the PROOF false. Imagine, as a gedanken experiment, that it is temperature that sets CO2 levels, and not vice versa. Also, one can acknowledge that humanity did indeed produce a lot of CO2 from fossil fuels.

If the temperature were constant and it drives the CO2 equilibrium value, then the equilibrium values of CO2 would remain constant. That means then that there is somewhere a mechanism that takes up or releases CO2 if this amount is changed somehow by an external process. Now, if you burn a lot of fossil fuels, you are going to put much more CO2 in the atmosphere, and the regulatory mechanism will "sink" an equal amount. However, the amount of fossil-fuel related CO2 (tracable with isotope analysis) will then of course rise in the atmosphere: most CO2 will be from fossil-fuel origin, but its LEVEL will be determined by the causal system driven by temperature.
Also, because burning fossil fuels consumes O2, one would see a decrease in O2 on par with the consumption of fossil fuels, and hence with the immediate production of CO2. If the regulatory mechanism driven by temperature has some inertia, one would indeed see, upon a rise in fossil fuel burning, an immediate CO2 rise, and an immediate O2 decrease ; but the CO2 level would then be steered by the control mechanism to its equilibrium value.

Now, imagine that the temperature rises for some or other reason. Now the equilibrium set value of CO2 will rise too. And what would we observe then ? We would observe:
1) a rising equilibrium value of CO2 in the atmosphere
2) a correlation between the CO2 increase in the atmosphere and the O2 decrease in the atmosphere
3) an isotopic composition which indicates that an increasing fraction of the CO2 content in the atmosphere is from fossil fuel origin.

In other words, this gedanken experiment, with its working hypothesis that temperature drives CO2 equilibrium values, is entirely in agreement with observations. That's no proof of course. It is only a proof that these 3 observations DON'T PROVE any causal relationship between rising CO2 levels in the atmosphere and human CO2 production by fossil fuel burning, given that they are also compatible with a model in which this is not assumed.

Again, don't understand me wrong: I didn't say that I proved that human CO2 production is NOT responsible for the rise in CO2 in the atmosphere. I only indicated that the arguments that are advanced as PROOF of this, are not a proof (although, I admit, suggestive), because they can be compatible with a working hypothesis which is the inverse of the to be proven statement.

If you want an analogy, consider that you are on the seaside. It is rising tide but you don't know what a rising tide is. You see somebody poor heavy water in the sea, you see the sealevel rise, and you accuse him of rising the level of the sea. For that, you do an isotopic analysis, and you show that there is more heavy water than usual present in the water that is rising at the shore. You also see that when he poors in a lot of water, the water level rises a bit faster, and when he poors in slower, the water rises a bit slower (on a background of steady rising). From this, you conclude that the guy is making the sealevel rise.

Again, don't understand me wrong. I'm not saying that there is no CO2 rise because of human fossil fuel consumption, that this doesn't lead to AGW, and so on. This is very well possible, and even plausible. But to say that it has been scientifically established requires one to envision ALL POSSIBLE WAYS IN WHICH THIS COULD NOT BE TRUE, and then exclude them one by one, so that only one remains. I DON'T SEE THIS BEING DONE. I rather see a lot of suggestive stuff, but no critical analysis of how all this could not be indicating what it is "supposed to indicate". And that, in my book, is bad science.

 

[Andre]

But the first thing in greenhouse effect is understanding how it works.

The global warming hypothesis assumes that the difference between basic Earth black body temperature and actual atmospheric temperature is caused by radiative properties of the greenhouse gases, of which water vapor is the most important, basically nullifying all other mechanisms. In reality it is convection and latent heat transport, which heats the atmosphere from the surface at daylight, while there is no comparable mechanism at night to cool it again. So this mechanism is one way only. This can be demonstrated when comparing day and night lapse rates in the atmosphere, where the difference between day and night is greatest at the Earth surface

http://mtp.jpl.nasa.gov/missions/texaqs/austin_poster/Image11.gif

http://mtp.jpl.nasa.gov/missions/texaqs/austin_poster/MTP_Austin_Paper.htm

Caption:
The figure to the right uses PNNL radiosonde data to show the diurnal variation of temperature profiles for August 31, 2000, at La Marque. The UTC launch times were 0501 (pink), 0758 (red), 1106 (light blue), 1401 (green), 1700 (white), 2000 (yellow) and 2300 (grey). It is clear that ground-level nighttime inversion vanishes between 1401 and 1700 UTC, and reappears after 2300 UTC. Since all but one Electra take off was before 1600 UTC, and all but two landings were after 2300 UTC, it is unlikely that the Electra would have encountered any inversions.

Hence the upper levels hardly cool at night as the only cooling mechanism is ... greenhouse effect, radiation out. And at those levels, with strongly reduced water vapor, radiation escapes to outer space much easier. This effect appears to be neglected in the IPCC endorsed literature and if you don't account for it in the models, you're basically stuck to the GIGO principle.

It is all in this thread, discussing the Chilingar et al 2008 study.

https://www.physicsforums.com/showthread.php?t=252066

In this mechanism the concentration of greenhouse gasses for temperature is strongly reduced. More greenhouse warming simply increases the convection rate, removing the excess heat again from the surface.

 

[jostpuur]

If you look at those graphs, you see that the direct measurements of temperatures, and other indirect measurements based on tree rings and all that, agree very well during approximately the time 1850-1980. So if the measurements agree on such long interval, and then the reliable direct measurements show dramatic rise in the latest years near 2000, isn't the whole graph genuinely honest and alarming hockey stick then?

 

[Andre]

If you look at those graphs, you see that the direct measurements of temperatures, and other indirect measurements based on tree rings and all that, agree very well during approximately the time 1850-1980. So if the measurements agree on such long interval, and then the reliable direct measurements show dramatic rise in the latest years near 2000, isn't the whole graph genuinely honest and alarming hockey stick then?

But they do not! Look at the big gap between the measured temperatures and the reconstruction, with and without blade of the hockeystick at the very end. Moreovere the red CRU temperatures hitting the roof at >0.9 degrees is very dishonest Just check the real numbers.

 

[jostpuur]

I see the gap at the very end, near 2000, but I was pointing out that the measurements agree earlier during somewhat long interval 1850-1980. Of course it is puzzling that there seems to be disagreement in the end, but the reconstructions look like reliable for little bit longer intervals. And on the other hand the direct measurements are reliable for short intervals too. So when you put this together, the entire hockey stick looks pretty reliable.

 

[Andre]

... I'm not saying that there is no CO2 rise because of human fossil fuel consumption, that this doesn't lead to AGW, and so on. This is very well possible, and even plausible. But to say that it has been scientifically established requires one to envision ALL POSSIBLE WAYS IN WHICH THIS COULD NOT BE TRUE, and then exclude them one by one, so that only one remains. I DON'T SEE THIS BEING DONE.

The problem with that is if you try for instance albedo and temperature like here, you suddenly find a plausible correlation/causation without any CO2:

on the other hand if you'd test paleo temperature reconstructions based on CO2 (Van Hoof et al 2008) versus other reconstructions like here the match is rather underwhelming:

See the problem Jostpuur?

 

[vanesch]

If you look at those graphs, you see that the direct measurements of temperatures, and other indirect measurements based on tree rings and all that, agree very well during approximately the time 1850-1980. So if the measurements agree on such long interval, and then the reliable direct measurements show dramatic rise in the latest years near 2000, isn't the whole graph genuinely honest and alarming hockey stick then?

The graph (especially the 2001 graph) wanted to display that the dramatic rise in 1990-2000 was exceptional, and wanted to show that never in the last 1000 years, the *level* as well as the *slope* was reached in an obvious and "order of magnitude" way.

The problem is that if this rise is not reproduced in the proxies, then that means that the proxies (for instance through a low-pass filtering effect) don't follow such quick rises, but smoothen them out. And that means that if there have been such "glitches" in the past, we probably won't see them either. So the very fact that the big rise in 1990-2000 wasn't seen in the proxies means that they don't show such quick rises. It isn't a surprise then that they didn't show them in the past, and hence the fact that they don't show them in the past is no proof anymore that they didn't happen, as we have under our very nose an example of when there was a quick rise in the actual temperature and no obvious signal in the proxies. If there had been a similar glitch around the year 1000, the proxies would have reacted as they are reacting now, and wouldn't have followed the temperature glitch. So we don't see it. That's no proof that there hasn't been any.

That the proxies correspond on some time scale with the temperature shouldn't surprise us either, as proxies need to be calibrated. So you need to take some patch in time to set equal measured temperatures and proxy data.

Finally concerning the *level* of the temperatures, contrary to the 2001 plot which indicated a proxy which did show uniform lower temperatures than recently, you clearly see now that different proxies don't agree and that we are completely within the "noise".

 

[Bored Wombat]

Let us concentrate exactly (we're using indeed the same data :-) on this "hockey stick".

Compare it to the initial hockey stick on p 3 of
http://www.ipcc.ch/pdf/climate-changes-2001/scientific-basis/scientific-spm-en.pdf

the summary for policy makers in 2001.

Now, admit that there is a world of difference in the convincing power that we are *on an exceptional and dramatic temperature rise* which was the aim of that plot (with well-choosen coloring too) in the last century - a rise that was OBVIOUSLY an order of magnitude larger than what had happened in the last 1000 year.

Certainly the emphasis of the average estimate rather than the range of error does more to create that impression, but the reconstructions are all largely similar.

An average line on this graph would do the same thing.

There is another error in the presentation of the 2007 plot. That is the visual confusion (using well-chosen coloring) of the proxy data and the actual measurements. Clearly, the proxy data are not 100% the same as the actual measurements (the solid black curve doesn't coincide perfectly with the proxies). That means that there is a dynamical system in between both, which can be for instance, a low pass filter.

More likely a more limited global coverage.

Even better: shift the instrument data and the smooth grey curve back about 1000 years. You'd find about equal agreement.

Not if you let your eye average the temperatures a little. There are four proxies up by the Mann et al. curve, and only two down by the D’Arrigo et al. curve. You'd guess a 0.2°C of warming occurred then. Whereas now we have four times that.

Leave away the current data (which are not the same as the proxies), and show only the proxies. Do you think that this still has the "hockey stick" conviction power ? You only see a smooth rising before 1000 AD, then a dip and indeed a slightly stronger rise in the last century. NOTHING TO DO with the dramatic effect displayed in the 2001 report. Where is the scientific honesty here ?

I think the data is pretty similar.

 

[Bored Wombat]

Important is the observation that the blade of these hockeystick is glued upon it and that the proxies are not following which basically already refutes the robustness of these proxies.

Has there been a scholarly response to the paper to that effect?
I see that the recent climate change has been sudden, and that the proxies don't tend to extend into the modern era.

But there is more, Mann et al 2008 admit that the adbundantly used and recycled tree ring proxies are basically flawed by showing the difference in skill in fig 2:

Sorry, I can't find that admission. Where is it?

 

[Bored Wombat]

The global warming hypothesis assumes that the difference between basic Earth black body temperature and actual atmospheric temperature is caused by radiative properties of the greenhouse gases, of which water vapor is the most important, basically nullifying all other mechanisms.

If it doesn't nullify all other mechanisms, but works additionally to them, then there would still be an effect on climate if greenhouse gasses are increased in atmospheric concentration.

And the four paleohistorical papers estimating past climate sensitivity above do show that historically at least there has been a climate sensitivity of about 3°C per doubling of CO₂.

Surely if convection were nullifying the greenhouse effect now it would have also done it in the past?

 

[vanesch]

I think the data is pretty similar.

It is not just about the data, it is about the presentation, which has been set up graphically to "make the point".

And just taking averages doesn't do the thing, exactly for the reasons I explained. Let us not forget that the aim of that plot is NOT to show that there has been a recent rise - we wouldn't need proxies for that, it is in the instrumental data. Yes, there has been a temperature rise of the last few decades.

The point the plot wanted to make, and its visual representation did so extremely well in the 2001 plot, was that this rise was *exceptional* and hadn't occurred (or any similar change hadn't occured) in the last 1000 years or so, and even longer. It also wanted to make another point, that the value of the current temperature was also *much* higher than any value reached in the last 1000 years.

However, what we clearly see is that the proxies don't follow the quick rise now - even though they are probably "tuned" to do so, as proxies need to be calibrated, and hence have some part of the current instrumental data record used in their calibration to determine absolute value and sensitivity to variations.
One shouldn't therefor be surprised that *all proxies* more or less coincide over a lapse of instrumental record: it has been used for their calibration ! That explains 1) their good correlation to the instrumental record from 1850 - 1950 and 2) the smallness of their variability over that period: they just re-emit their calibration. It is already a problem that they don't reconstruct the quick instrumental rise in the last decades. So they already don't represent correctly "short term dynamics".
Their divergence in the past then indicates the differences in dynamics and the lack of 100% correlation with temperature. This is not necessarily statistical noise which averages out to 0. So taking averages doesn't provide you necessarily with a *less biased* estimator, and certainly not with a *dynamically more accurate* estimator.

Imagine that their correlation with temperature and with its dynamics is relatively poor. If you have several of those, with different correlations, and you average them out, chances are that you will find a more or less constant value. You might have even degraded the correlation with temperature. You might not have a thermometer at all. The "good" correspondence in 1850 - 1950 simply comes then by forcing the calibration: they all reproduce their calibration curve.

This is why the visual representation of the 2007 data, WITHOUT the instrument record, gives you the most faithful reconstruction of temperature through these proxies: one gets an idea of the accuracy of the proxy measurements, and one gets an idea of the overall dynamics. Well, if you do that, there's nothing that *clearly* indicates an *exceptional* rise in the last few decades, and an *exceptional level*. Of course, there is a rise, and of course temperatures are high, but the overall impression is that they reach about the same level as 1000 years ago, and that between that period and now, there have been periods of cooling, and of heating, very comparable to what happens now.

Those data, and their honest representation (without the instrumental data) don't convince anybody that something very alarming is going on right now, and if you see something else in that, then I don't know what you see. If these were interest rates of different banks, would you panic right now ? More to the point, doesn't the current situation, described with the proxies, ressemble the situation just before 1000 ?

In other words, the proxy data don't *prove* that no such rise has taken place in the past, or that the current levels are exceptionally higher. They *simply don't contain that information*.

 

[Bored Wombat]

Well, again, there is no tight proof (although there is suggestive evidence) for this. What is usually taken as the evidence that the rise in CO2 is human-caused ?

1) there is the correlation between the human consumption of fossil fuels and of its concentration in the atmosphere

Yes. About half of the CO₂ released by fossil fuels combustion remains in the atmosphere.

The bulk of the remainder is dissolved in the oceans, and it's movement there can be traced. (Because it has different Isotope rations from the background, and everything since 16th July 1945 had higher radioisotopes).

2) there is the correlation between the decrease of oxygen in the atmosphere and the rise in CO2

Yes. Anticorrelation. Showing that the extra CO₂ is from the combustion of something. Perhaps forests.

3) there is the isotopic composition of CO2 in the atmosphere, which shows that it has a rising component that most probably comes from fossil fuels (lower C-14 content).

Yes, also lower C-13 content, showing it is from organic origin. Together with the lower C-14 content we have it locked to fossil fuels.

This is direct evidence that can be compared with the (strong) circumstantial evidence that we have released more than enough CO2 into the atmosphere to affect the change in atmospheric concentration.

However, although this is of course suggestive evidence, this is no proof at all.

Well, we know where the CO₂ came from.

The reason it remains in the atmosphere is about the capacity and kinetics of the world's oceans and terrestrial biosphere to sink it.

And the oceanic one is probably inversely proportional to temperature. As ice ages ends, it seems as if about 800 years after the warming begins, the oceans start outgassing CO₂. So in about 2700AD, they're going to have another positive feedback kick in, and they're not going to have our main sink for CO₂.

And we have seen that the CO2 levels started coming up before 1900, but temperatures didn't rise until after that, so I think we know what the atmospheric CO₂ concentration has initially been more dependent on the emission of CO₂ into the atmosphere than an increase in temperature.

But the oceanic sink for CO₂ is under much study, and seems to be at about 1/3rd of it's long term capacity, and it showing signs of slowing slowing (proportionally speaking ... it is still absorbing more than ever linearly speaking, but emissions are increasing faster than that). And it is temperature (and wind) dependent. But despite the nature of the world's carbon sinks, we know what the source is ... the combustion of fossil fuels.

 

[Bored Wombat]

The problem with that is if you try for instance albedo and temperature like here, you suddenly find a plausible correlation/causation without any CO2:

We do know that CO2 is a greenhouse gas. So we have causation there as well. Albedo will certainly make a difference as well. But that does not discount the last 100 years of optics.

 

[Bored Wombat]

The problem is that if this rise is not reproduced in the proxies, then that means that the proxies (for instance through a low-pass filtering effect) don't follow such quick rises, but smoothen them out.

We know that not to be the case, because we know from proxy data the the warming at the end of the Younger Dryas (11550 calendar years BP) was quicker than the warming we see now.

So rapid climate change more rapid than current can be inferred from proxy data.

 

[jostpuur]

The graph (especially the 2001 graph) wanted to display that the dramatic rise in 1990-2000 was exceptional, and wanted to show that never in the last 1000 years, the *level* as well as the *slope* was reached in an obvious and "order of magnitude" way.

The problem is that if this rise is not reproduced in the proxies, then that means that the proxies (for instance through a low-pass filtering effect) don't follow such quick rises, but smoothen them out. And that means that if there have been such "glitches" in the past, we probably won't see them either.

Assuming that what you say here is correct, I have two comments:

One: While this point is valid, this point didn't quite become clear in the Andre's post where he showed the hockey stick with direct measurements removed, and spoke about scientific honesty. It looked like he was setting the resent temperature rise under question, which is quite different from saying that reconstructions would have smoothened out possible spikes already earlier.

Two: While the possible existence of earlier spikes cannot be denied by using the temperature reconstructions, on the other hand, the resent temperature rise has been modeled by taking into account the man made greenhouse emissions. So isn't it then quite unlikely, that the resent temperature rise would be only a one natural spike among the many other spikes that we don't see?

In other words, the proxy data don't *prove* that no such rise has taken place in the past, or that the current levels are exceptionally higher. They *simply don't contain that information*.

But are you trying to say, that convincingly alarming information wouldn't exist?

 

[Bored Wombat]

However, what we clearly see is that the proxies don't follow the quick rise now - even though they are probably "tuned" to do so, as proxies need to be calibrated, and hence have some part of the current instrumental data record used in their calibration to determine absolute value and sensitivity to variations.

How do you know that we're not just seeing the modern edge of the proxy data?
That is what I assumed from the graph.

 

[vanesch]

Yes. About half of the CO₂ released by fossil fuels combustion remains in the atmosphere.

The bulk of the remainder is dissolved in the oceans, and it's movement there can be traced. (Because it has different Isotope rations from the background, and everything since 16th July 1945 had higher radioisotopes).


Yes. Anticorrelation. Showing that the extra CO₂ is from the combustion of something. Perhaps forests.


Yes, also lower C-13 content, showing it is from organic origin. Together with the lower C-14 content we have it locked to fossil fuels.

This is direct evidence that can be compared with the (strong) circumstantial evidence that we have released more than enough CO2 into the atmosphere to affect the change in atmospheric concentration.

I acknowledged that. I only pointed out that there is a difference between the ORIGIN of the actual CO2 in the atmosphere (partly from fossil, no doubt), and its LEVEL, which can be set or not by a regulation mechanism. The two have nothing to do with each other (see my simplistic analogy with heavy water and the tide rise).

Another example: is it because most of my pocket change comes from the local supermarket that they are the ones who determine how much money I have ?

Well, we know where the CO₂ came from.

Yup. I didn't dispute that.

The reason it remains in the atmosphere is about the capacity and kinetics of the world's oceans and terrestrial biosphere to sink it.

THAT is the real "level setter". This has nothing to do with what is the origin of (part of) atmospheric CO2 - which is undeniably from fossil fuels.

So if you want to infer that the atmospheric CO2 LEVEL is changing by a specific external source (fossil fuel burning), then you have to demonstrate that the regulatory mechanism is OVERWHELMED by this source. THAT would be an indication. But as you say yourself, this is not clear at all. This is possible, but this has not been demonstrated beyond doubt - and the actual arguments here are not even presented as the real arguments. Instead, as "proof", is presented something which discusses the ORIGIN, but not the LEVEL.

Especially because all proportions taken into account, the amount of fossil-fuel CO2 is small compared to the entire inventory of CO2 in the circuit (as the amount of heavy water poored in was small as compared to the amount of water in the sea).

And the oceanic one is probably inversely proportional to temperature. As ice ages ends, it seems as if about 800 years after the warming begins, the oceans start outgassing CO₂. So in about 2700AD, they're going to have another positive feedback kick in, and they're not going to have our main sink for CO₂.

Or, it might be that it is TEMPERATURE that drives the CO2 level, and not vice versa. If it is temperature which determines CO2 level, then any external CO2 source (which remains small compared to the total inventory of CO2 in the circuit). In that case, it is not "feedback", but just "following the set level", and the temperature might, or might not, be mainly steered by CO2 content.

And we have seen that the CO2 levels started coming up before 1900, but temperatures didn't rise until after that, so I think we know what the atmospheric CO₂ concentration has initially been more dependent on the emission of CO₂ into the atmosphere than an increase in temperature.

And then there are paleo data where the time correlation is the opposite (temperature rises first, and then CO2 follows - although this was first presented the other way around).

Hey, human computing power also started rising before temperature rose. Is computing power therefor a drive of global temperature.

A correlation is not a causal link per se. It could be, but it could also not be.

But the oceanic sink for CO₂ is under much study, and seems to be at about 1/3rd of it's long term capacity, and it showing signs of slowing slowing (proportionally speaking ... it is still absorbing more than ever linearly speaking, but emissions are increasing faster than that). And it is temperature (and wind) dependent. But despite the nature of the world's carbon sinks, we know what the source is ... the combustion of fossil fuels.

Yes, this is still under study.

Again, I'm NOT arguing that there is no AGW, and that human-caused fossil fuel combustion has nothing to do with it. Far from it. Actually I'm a long-term nuclear power proponent and it is one of my main reasons. But with all I have read, I find more reasons to doubt the scientific certainty that is displayed more than anything else.

What I am objecting to in this whole business is that the ARGUMENTATION IS ALL WRONG. About all arguments presented as scientific proof beyond reasonable doubt are LOGICALLY ERRONEOUS or factually misrepresented. What scares me is that these ELEMENTARY objections - I'm not a climate scientist - are not even adressed, and that nobody in the entire community points this out - as if it were wrong to be critical towards the credo.

 

[vanesch]

How do you know that we're not just seeing the modern edge of the proxy data?
That is what I assumed from the graph.

But I'm not the one claiming "scientific proof". This is my whole argument. Scientific proof means: "we've eliminated beyond doubt all other reasonable explanations". So where is your PROOF that we are seeing the modern edge of proxy data, and that *there doesn't exist any other reasonable explanation* for it ? THEN you have a case. Now, you only have suggestive evidence. Which I acknowledge.

 

[vanesch]

We do know that CO2 is a greenhouse gas. So we have causation there as well. Albedo will certainly make a difference as well. But that does not discount the last 100 years of optics.

We don't know what is the *real effect* of CO2. There is circular reasoning here. Of course I don't doubt that CO2, in a stationary atmosphere, has a radiative heating effect. That's given by MODTRAN for instance, and its effect is small. All the rest: effects on convection, on water vapor, on land response, on ocean currents, on whatever, are complicated problems, and it is not clear what the total effect is. So the "physical/chemical" effect of CO2, as a greenhouse gas, is, in very idealized circumstances, limited to the about 0.5 - 1 degree for a doubling, given by MODTRAN.

And then the reasoning becomes circular: 1) BECAUSE we see a correlation, recently, between rising CO2 levels and temperature, this must be caused by CO2, so this is then: observation --> strong greenhouse gas effect and 2) because CO2 is a strong greenhouse gas, this proves that the correlation observed is a causal effect.

But this has nothing to do with the small greenhouse effect of CO2 in an idealised atmosphere as shown by MODTRAN. You can't at the same use observations to prove that CO2 is a strong greenhouse gas (under the assumption that there is a causal link), and then use that conclusion to show that there was a causal link. In other words, you take as a premise, the conclusion you want to reach, and then, no wonder, you arrive at some elements that confirm your hypothesis.

 

[Bored Wombat]

Another example: is it because most of my pocket change comes from the local supermarket that they are the ones who determine how much money I have?

That analogy is inappropriate, because there are only 3 sources or sinks of fossil fuels. Human activity, the oceans, and the terrestrial biosphere. The source of the atmospheric increase is from fossil fuels.

There's no equivalent of your investments or salary in this system.

THAT is the real "level setter". This has nothing to do with what is the origin of (part of) atmospheric CO₂ - which is undeniably from fossil fuels.

Well, as you say you have no evidence for that.

Whereas we know that in the past for approximately current temperatures, CO2 concentratiions should be about 300 or 320ppm, not 385ppm:

http://www.ncdc.noaa.gov/paleo/pubs/luethi2008/fig2.jpg

So we know that it is not caused by temperature.

Especially because all proportions taken into account, the amount of fossil-fuel CO2 is small compared to the entire inventory of CO2 in the circuit

But it is large compared to the increase in atmospheric concentration.

And then there are paleo data where the time correlation is the opposite (temperature rises first, and then CO2 follows

Right. So we know that the current warming is not like the ends of past ice ages, because the CO₂ has moved first.

Which fits with our other understandings, because Homo Neanderthalensis didn't have coal mines.

- although this was first presented the other way around).

You claim that this was known and held back from publication? I recall a paper talking very tentatively about it. It seemed to me that it was published as soon as it was noticed. Of course the age of the air in an ice core (from which the atmospheric CO₂ concentration is measured) is younger than the age of the ice (from which local temperature at the time of freezing is inferred), so they had reason to state it tentatively.

From what do you claim that this finding was held back?

Hey, human computing power also started rising before temperature rose. Is computing power therefor a drive of global temperature.

A correlation is not a causal link per se. It could be, but it could also not be.

That is true, but in this case the causal link is known and understood. It is the greenhouse effect.

 

[vanesch]

One: While this point is valid, this point didn't quite become clear in the Andre's post where he showed the hockey stick with direct measurements removed, and spoke about scientific honesty. It looked like he was setting the resent temperature rise under question, which is quite different from saying that reconstructions would have smoothened out possible spikes already earlier.

I'm not Andre :-) Andre thinks that there is no AGW. I'm agnostic about AGW, I'm only indicating that what is presented - especially by the IPCC - is not scientifically rigorous as Feynman would have liked it, in that one would have tried to show oneself wrong. On the contrary, the IPCC is built up as an argument for AGW, not as a critical scientific analysis. I surely find much material presented by the IPCC very suggestive, but one should then be aware that it was presented TO MAKE A CASE, and not as a scientific analysis. Nevertheless, it is always presented as if it were the ultimate scientific analysis that PROVES AGW beyond doubt, and anyone being critical towards it is almost seen as a crackpot (or a heretic?).

This is like listening to the lawyer or listening to the judge. The lawyer builds a case. The judge tries to see the truth. When the lawyer is confused with the judge, truth is lost.

I'm just trying to see the holes in the lawyer's argument - as a judge would do.

Two: While the possible existence of earlier spikes cannot be denied by using the temperature reconstructions, on the other hand, the resent temperature rise has been modeled by taking into account the man made greenhouse emissions. So isn't it then quite unlikely, that the resent temperature rise would be only a one natural spike among the many other spikes that we don't see?

Yes, and those models are built exactly upon effects by CO2 as taken from these data. That's the circular reasoning I pointed towards in another post here.

But are you trying to say, that convincingly alarming information wouldn't exist?

I think there is more than enough SUGGESTIVE information to be indicative that the hypothesis of AGW is a plausibility, and given its potential disastrous effects, I think that until we find out more, we should take this into account in our policies.

However, "alarming" and "scientifically sound" are not the same. I think the scientific case for AGW is far from closed, and I wouldn't be surprised that it turns out not to be there, or be there to a much lesser extend than claimed now. It could also be there the way people present it. But the honest answer is that we don't know yet. Let us say that most of the material presented by things such as the IPCC is not INCOMPATIBLE with the existence of AGW - but you would not expect otherwise from a lawyer's case, would you ?
I am appalled at the fact that many "proofs" presented by the IPCC have logical holes in them which are not adressed.

When presenting AGW AS IF IT WERE A SCIENTIFIC FACT BEYOND DOUBT - which I try to show it isn't - we are committing scientific dishonesty.

 

[Bored Wombat]

But this has nothing to do with the small greenhouse effect of CO2 in an idealised atmosphere as shown by MODTRAN. You can't at the same use observations to prove that CO2 is a strong greenhouse gas (under the assumption that there is a causal link), and then use that conclusion to show that there was a causal link. In other words, you take as a premise, the conclusion you want to reach, and then, no wonder, you arrive at some elements that confirm your hypothesis.

This is correct to within certain boundaries.

The climate sensitivity might be as low as 1.5 or 1.6°C per doubling of CO₂, or it might be as high as 5.5 or even 6°C per doubling. But outside that range it just doesn't fit the observational and paleohistorical data.

So yes, it is poorly known, for the reason you describe, but you exaggerate the effect of this uncertainty. Even a 1.5°C per doubling, with the increase in CO2 concentration since the anthropogenic ear of 385/280 = 1.375 or 0.46 doublings gives a warming of 0.69°C due to CO₂ increase alone. Which is probably most of the observed warming, even taking into account that 60% of the climate's response to an increase in radiative forcing isn't complete for 25-50 years (the large error here due again to the error in climate sensitivity to CO₂ - so it will be shorter times if climate sensitivity is low.)

The bottom line is that we certainly don't know it all, but we do know that the current warming is very likely to be mostly anthropogenic.

 

[vanesch]

That analogy is inappropriate, because there are only 3 sources or sinks of fossil fuels. Human activity, the oceans, and the terrestrial biosphere. The source of the atmospheric increase is from fossil fuels.

But do you know their reactions to other parameters like temperature accurately enough as to be able to show that the difference is DRIVEN by the fossil-fuel consumption ? The source of atmospheric CO2 is partly from fossil fuels, but do you know precisely how oceans and land are reacting to CO2 concentrations and cannot act as a regulator ?

There's no equivalent of your investments or salary in this system.

Can't oceans or the terrestrial biosphere be "sources" in the sense of being less of a sink than they used to be just because of regulation properties ? Imagine that oceans "want" to have a higher level of atmospheric CO2 for one or other reason. If there wouldn't be any fossil fuel production, they would then outgas more CO2. Because there is fossil fuel CO2, they don't outgas as much, but they even take up some. But they still set the level.

Well, as you say you have no evidence for that.

I don't have to. YOU are making a case. You have to show that no such evidence can exist. That's my point. Before you have a proof, you have to have explored all possible other explanations.

Whereas we know that in the past for approximately current temperatures, CO2 concentratiions should be about 300 or 320ppm, not 385ppm:

http://www.ncdc.noaa.gov/paleo/pubs/luethi2008/fig2.jpg

So we know that it is not caused by temperature.

It is not caused by temperature, but then it comes 600 years (I think? From the top of my head) AFTER the temperature increase, and is almost perfectly correlated. This isn't directly a demonstration that CO2 DROVE temperature. If anything causal here, it is temperature which drives CO2.
So you are just talking about the quantitative effect. The world is different now. Land usage is different. The response might be different. The exact dynamics hasn't been elucidated. It is not because you've seen a different response in the past that this is a PROOF that this time the quantitatively different response (in as much as the proxies are numerically accurate) is FOR SURE not caused partly by temperature. That could only be the case if you have a perfect physical dynamical model of the relationship between temperature, land usage and CO2 content. Hell, the proxy might even have a cross-correlation! Maybe the proxy for CO2 calibration is partly dependent on temperature or vice versa. How can you know ?

But it is large compared to the increase in atmospheric concentration.

Yes, if you can quantitatively demonstrate that the regulatory mechanisms are overwhelmed, then indeed this indicates that fossil fuel combustion contributes - at least temporarily - to the atmospheric CO2 concentration. But the ARGUMENTS PRESENTED don't prove this. This is my point.

Right. So we know that the current warming is not like the ends of past ice ages, because the CO₂ has moved first.

Nevertheless, before the 600 year shift was known, these data were presented as PROOF THAT CO2 DROVE TEMPERATURE. It was one of those "undeniable proofs" which fell on their face.

Which fits with our other understandings, because Homo Neanderthalensis didn't have coal mines.

This is again taking your conclusion as an argument. You ASSUME that it is human-driven CO2 which is now the main cause of rising of atmospheric CO2, and you analyse paleodata using this, and then you arrive to the conclusion that, well, it must be human-driven CO2 which is now the main cause of rising atmospheric CO2. Again, the only real proof would be if you had a very good physical model which could predict CO2 responses as a function of temperature (NOT using these paleodata of course), and then if you could predict these effects, and show that it also explains current rise as a function of fossil-fuel combustion. Just fitting a dynamical black box model to paleo data, and seeing the difference with now, is no proof. It is at most suggestive.

You claim that this was known and held back from publication? I recall a paper talking very tentatively about it. It seemed to me that it was published as soon as it was noticed. Of course the age of the air in an ice core (from which the atmospheric CO₂ concentration is measured) is younger than the age of the ice (from which local temperature at the time of freezing is inferred), so they had reason to state it tentatively.

I don't mean any intentional dishonesty. I only see that those same data were once used as a "proof" that CO2 drove temperature. Another "hockeystick" if you want. And then it turned out to be the other way around.

At no point I have seen the IPCC hammering that their previous argument was ERRONEOUS and turned out to be FALSE. I'm not claiming that the finding was withheld, I'm only pointing out the difference in publicity that was given to the CO2 --> temperature correlation and then the fact that it was discovered that this was backward.

That is true, but in this case the causal link is known and understood. It is the greenhouse effect.

The problem is that this is again circular: it is used as a PROOF for the greenhouse effect, and at the same time it is EXPLAINED BY that greenhouse effect.