Accuracy of An Inconvenient Truth

[swansont]

All I said is that it does not show a comparison of anthropogenic vs natural forcings. The OP claimed anthropogenic forcings are predominate, i.e. greater than natural forcings. That claim requires a bottom line comparison which I haven't seen yet. There is no doubt that anthropogenic forcings have increased as man has progressed in his industrial endeavors but is the forcings of man truly the greatest forcings of all. I'm not convinced the data that takes into account all of the variables even exists to make that claim. Do we even know all of the variables? Global warming is real, I just don't agree with the claim that we are the biggest cause.

 

Is that a "no," then? Without data, it's just argument from incredulity.

[doG]

Is that a "no," then? Without data, it's just argument from incredulity.

Is that a yes it does? Please point out the other natural forcings...

[swansont]

Is that a yes it does? Please point out the other natural forcings...

 

 

And we've come full circle...again. I refer you to my remarks in post 173, and I'm done.

[doG]

And we've come full circle...again. I refer you to my remarks in post 173, and I'm done.

No we haven't. I realize that the chart you're referring to reflects the increase in anthropogenic forcings. It does not reflect total anthropogenic forcings vs total natural forcings. The OP claimed that anthropogenic forcings are the predominate driver of global warming. That implies that total anthropogenic forcings are greater than total natural forcings and so far no data has been posted that supports that claim.

[bascule]

No we haven't. I realize that the chart you're referring to reflects the increase in anthropogenic forcings. It does not reflect total anthropogenic forcings vs total natural forcings. The OP claimed that anthropogenic forcings are the predominate driver of global warming. That implies that total anthropogenic forcings are greater than total natural forcings and so far no data has been posted that supports that claim.

 

http://www.scienceforums.net/forums/showpost.php?p=285407&postcount=29

 

[img']http://www.gsfc.nasa.gov/gsfc/earth/pictures/hansen010302/figure2m.gif[/img]

[SkepticLance]

Swansont.

I don't think you looked at the graphs hard enough. The reference you posted for the USNA gave exactly the same graph as the one I posted, except that yours was in Fahrenheit, whereas mine was in Celsius. A difference that makes no difference.

 

If you look again at the dark black line on the graph, representing the Canadian model that was adopted by USNA, you will see that it shows a temperature rise of 1.5C for the 20th Century. We know from history that the US warmed only 0.5C. Thus a 300% exaggeration.

 

This makes the Canadian model prediction of 5.5C for the 21st Century look very suspect. Apply the 300% correction, and we are back to 1.8C. This is close to Hansen's prediction of 0.75C for 50 years.

 

All this suggests to me that global warming models have been giving alarmist exaggerated predictions, which we should all take with a big pinch of salt.

 

bascule.

Posting the IPCC graph of estimated forcings again is not helping. Each of the values on the graph came from calculations and computer models. I think I have shown just how much we should trust computer models!

 

When you can come up with real world measurements, please get back to us.

[bascule]

I think I have shown just how much we should trust computer models!

 

One model was wrong, therefore all models are wrong! Q.E.D! Also, the Hansen paper uses satellite measurements.

[SkepticLance]

bascule.

You misinterpret my logic.

It is more : "If the model chosen by the USNA cannot be trusted, then who or what can we trust?"

 

If you look at the temperature increase on your much loved 'hockey stick', you will note that there is a clear trend line that is linear. If we extend that linear trend into the future for 50 years, guess what?

 

We end up with the Hansen 0.75C.

 

To me, the most rational interpretation of all this is to say that we are unlikely to have a temperature increase over 50 years of more than 0.75C.

 

The theoretical response to greenhouse gases is a curve, not a straight line. In other words, if we double the greenhouse gas increase, we get less than double the temperature increase. To maintain a linear increase in temperature, we need a growing increase in greenhouse emissions.

 

Add to that the fact that in the 1990's solar forcings reached an 8000 year high, and are thus unlikely to increase much more, and thus will not contribute to future global warming to any great extent, then it is seriously unlikely that future temperature increases will be more than linear.

 

Put it all together : 50 years = maximum increase 0.75C.

[bascule]

Nice red herring. Nobody's arguing any of that. The issue at hand has been whether anthropogenic forcings are predominant in driving climate change. Every time this comes up your response has been to pull a red herring and try to argue some other issues. I'm not going to fall for it, sorry.

 

Now what's your argument against Hansen's paper, which is essentially the smoking gun of anthropogenically-forced climate change?

 

And for that matter, do you have any argument against the IPCC's assessment of the forcings driving our climate system other than that they're calculated from empirical data?

 

How exactly do you expect them to DIRECTLY measure the relative strength of forcings affecting something as large as THE ENTIRE EARTH?

 

It sounds to me like you have no real criticisms of their methodology, other than that their results are calculated from empirical data rather than being observed directly.

 

Would you criticize the entire standard model for being calculated instead of empirically derived? Should we expect direct observations of quarks, the strong force, and the weak force before we accept they exist?

 

How about gravity? How about General Relativity?

[SkepticLance]

bascule.

Rather than get into a no-holds barred point by point battle, let me clarify my position.

 

We are in a debate. I read your position as (and correct me if I am wrong) :

"Anthropogenic greenhouse gases are the primary driver of global warming."

 

My position is NOT simply the opposite of yours. My position is :

"We do not know which of several possible drivers are dominant."

 

In other words, I am not saying you are wrong. Just that we do not know. For this reason, to support my position, I do not need to provide evidence that AGGs are not dominant.

 

I have a second position to argue. I know you are not fighting this point, but others are (or were). My second point is that "we need not view the 21st Century warmings with great alarm. Most predictions are exaggerated."

 

Now back to evidence. As I have said before, I do not demand 100% proof. There is no such thing. I just challenged you to come up with genuine empirical evidence. I know this is possible, since I have seen it. Not enough to persuade me that the story is cut and dried, but enough to persuade me that AGG's are a factor. Whether dominant or not appears to me to be still unproven. Either you are unaware of this evidence, or you are so fixated on non-empirical evidences that you cannot find a true empirical evidence.

 

Yet empirical tests are the foundation of science.

[swansont]

Swansont.

I don't think you looked at the graphs hard enough. The reference you posted for the USNA gave exactly the same graph as the one I posted' date=' except that yours was in Fahrenheit, whereas mine was in Celsius. A difference that makes no difference.

 

If you look again at the dark black line on the graph, representing the Canadian model that was adopted by USNA, you will see that it shows a temperature rise of 1.5C for the 20th Century. We know from history that the US warmed only 0.5C. Thus a 300% exaggeration.

[/quote']

 

 

Yes, it should make no difference at all. Except that the people who put the report together, and presumably have the actual numbers, give different values than the ones you quote. Where did you get your graph? Is it possible it came from a source that might be inclined to exaggerate in order to discredit?

 

Further, from what I read, from the USNA itself, was that the models were for predicting far more than temperature changes. It's a climate model. It looks like it was predicting the actual temperatures, too, as well as rainfall, and for individual areas of the US. Your assessment of the accuracy of the model is incomplete.

 

And lastly, the numbers you quote use a convenient abuse of statistics. Since the change was small, even if absolute difference of actual vs. predicted is small, the relative error is large. On top of that, the differences you point to in the model are skewed by the first decade; the 1900 data point is a about a half a degree low (curiously, 0.5F on the USNA website's graph, and 0.5 C on the one you linked to).

[doG]

http://www.scienceforums.net/forums/showpost.php?p=285407&postcount=29

[url']http://www.grida.no/climate/ipcc_tar/[/url]

Figure 9: Global' date=' annual-mean radiative forcings (Wm-2) due to a number of agents for the period from pre-industrial (1750) to present (late 1990s; about 2000) (numerical values are also listed in Table 6.11 of Chapter 6). For detailed explanations, see Chapter 6.13. [b']The height of the rectangular bar denotes a central or best estimate value, while its absence denotes no best estimate is possible.[/b] The vertical line about the rectangular bar with “x” delimiters indicates an estimate of the uncertainty range, for the most part guided by the spread in the published values of the forcing. A vertical line without a rectangular bar and with “o” delimiters denotes a forcing for which no central estimate can be given owing to large uncertainties. The uncertainty range specified here has no statistical basis and therefore differs from the use of the term elsewhere in this document. A “level of scientific understanding” index is accorded to each forcing, with high, medium, low and very low levels, respectively. This represents the subjective judgement about the reliability of the forcing estimate, involving factors such as the assumptions necessary to evaluate the forcing, the degree of knowledge of the physical/chemical mechanisms determining the forcing, and the uncertainties surrounding the quantitative estimate of the forcing (see Table 6.12). The well-mixed greenhouse gases are grouped together into a single rectangular bar with the individual mean contributions due to CO2, CH4, N2O and halocarbons shown (see Tables 6.1 and 6.11). Fossil fuel burning is separated into the “black carbon” and “organic carbon” components with its separate best estimate and range. The sign of the effects due to mineral dust is itself an uncertainty. The indirect forcing due to tropospheric aerosols is poorly understood. The same is true for the forcing due to aviation via its effects on contrails and cirrus clouds. Only the “first” type of indirect effect due to aerosols as applicable in the context of liquid clouds is considered here. The “second” type of effect is conceptually important, but there exists very little confidence in the simulated quantitative estimates. The forcing associated with stratospheric aerosols from volcanic eruptions is highly variable over the period and is not considered for this plot (however, see Figure 6.8). All the forcings shown have distinct spatial and seasonal features (Figure 6.7) such that the global, annual means appearing on this plot do not yield a complete picture of the radiative perturbation. They are only intended to give, in a relative sense, a first-order perspective on a global, annual mean scale and cannot be readily employed to obtain the climate response to the total natural and/or anthropogenic forcings. As in the SAR, it is emphasised that the positive and negative global mean forcings cannot be added up and viewed a priori as providing offsets in terms of the complete global climate impact. [based on Figure 6.6]

Uncertainties? Assumptions? Best estimate? Sorry, while I agree there are plenty of anthropogenic forcings I don't see how you can claim with any certainty that this proves total natural or anthropogenic forcings as a predominate cause.

[bascule]

Uncertainties? Assumptions? Best estimate? Sorry, while I agree there are plenty of anthropogenic forcings I don't see how you can claim with any certainty that this proves total natural or anthropogenic forcings as a predominate[/b'] cause.

 

Read the Hansen paper.

 

And I'm still waiting for any recent, peer-reviewed scientific papers arguing that natural forcings are predominant

[doG]

Read the Hansen paper.

This one?

...A caveat accompanying our analysis concerns the uncertainty in climate forcings. A good fit of observed and modeled temperatures (Fig. 1) also could be attained with smaller forcing and larger climate sensitivity, or with the converse. If climate sensitivity were higher (and forcings smaller), the rate of ocean heat storage and warming ‘‘in the pipeline’’ or ‘‘committed’’ would be greater, e.g., models with a sensitivity of 4.2- to 4.5-C for doubled CO2 yield È1-C ‘‘committed’’ global warming (3, 4). Conversely, smaller sensitivity and larger forcing yield lesser committed warming and ocean heat storage. The agreement between modeled and observed heat storage (Fig. 2) favors an intermediate climate sensitivity, as in our model. This test provided by ocean heat storage will become more useful as the period with large energy imbalance continues....

...Given the unusual magnitude of the current planetary energy imbalance and uncertainty about its implications, careful monitoring of key metrics is needed. Continuation of the ocean temperature and altimetry measurements is needed to confirm that the energy imbalance is not a fluctuation and to determine the net climate forcing acting on the planet. The latter is a measure of the changes that will be needed to stabilize climate. Understanding of the forcings that give rise to the imbalance requires more precise information on aerosols (35). ...

It sounds like Hansen et al are uncertain as well...

 

Now, I agree that global warming exists and that man contributes, significantly, to a cycle that we know occurs naturally. I agree with suggested monitoring and continued modelling to better understand what we can do about it, if anything. I only disagree with concluding that anything is the number one cause. Even Hansen's paper does not confirm that the energy imbalance is not a fluctuation.

[SkepticLance]

bascule said

 

And I'm still waiting for any recent, peer-reviewed scientific papers arguing that natural forcings are predominant

 

And you will not get them either. No-one has said such papers exist. No-one has claimed proof of either type of forcing being dominant. That is because such proof or even strong evidence does not exist. That is why I argue that we just do not know.

 

Swansont.

You claim that I am mis-using statistics. You are correct, of course. It is not possible to say for certain what the correct temperature prediction should be, and my method was very tongue in cheek. The real point is that global warming computer models are dreadfully misleading. There are none that can be called accurate.

 

Personally, I think that a simple linear projection from current trends is more likely to be correct than any current model. The great virtue of such a projection is that, at least, it is beginning from reality.

 

As I pointed out, with the probability that solar forcings will not increase (or not much), and with the temperature/carbon dioxide relationship being a diminishing curve, to see substantial temperature rises beyond current trends would require an enormous increase in carbon dioxide emissions. Unlikely!

[bascule]

And you will not get them either. No-one has said such papers exist. No-one has claimed proof of either type of forcing being dominant.

 

Not proof, but I've linked several papers which conclude that anthropogenic forcings are predominant.

 

There is no scientific case for the other side. Why is this?

 

It's been claimed this is the result of groupthink within the scientific community. However you and others have written other books and other sources which attempt to argue the opposite outside of the realm of peer-reviewed scientific literature.

 

It seems like there's no lack of people wanting to make the argument. The difference is that none of these arguments can survive the peer review process. Why is this?

 

That is because such proof or even strong evidence does not exist. That is why I argue that we just do not know.

 

I'm willing to agree there's a degree of uncertantiy as to the specific nature of the forcings affecting the climate system, and that what I've been linking are estimates. However, why does all scientific estimation show that anthropogenic forcings are predominant? Why is there no scientific paper arguing the opposite? Why doesn't Michaels have a paper arguing this position, for example?

[Dr. Dalek]

I'm willing to agree there's a degree of uncertantiy as to the specific nature of the forcings affecting the climate system, and that what I've been linking are estimates. However, why does all scientific estimation show that anthropogenic forcings are predominant? Why is there no scientific paper arguing the opposite? Why doesn't Michaels have a paper arguing this position, for example?

Perhaps, human arogance. Dispite the fact that we revolve around the sun we still think the world is centered around us.

Still looking for a paper. The Library science section has turned up nothing will try google scholar.

[swansont]

Personally' date=' I think that a simple linear projection from current trends is more likely to be correct than any current model. The great virtue of such a projection is that, at least, it is beginning from reality.

[/quote']

 

On what scientific basis do you make that assessment? Beginning from reality? Where do you see linear behavior over any appreciable stretch of time?

 

Linear projections will always hold for a small enough movement from the starting point, that's the whole basis for e.g. perturbation theory and Taylor series expansions. If the system is nonlinear, however, they fail pretty quickly. Plus, a linear projection is still a model, and they can't be trusted, right?

[swansont]

Swansont.

You claim that I am mis-using statistics. You are correct' date=' of course.[/quote']

 

Uncertainties? Assumptions? Best estimate?

 

...

 

It sounds like Hansen et al are uncertain as well...

 

If you don't understand how science is done, you can't hope to argue, on scientific principles, why any particular conclusion is wrong. Misrepresenting statistics is not a scientific argument. Harping about the presence of uncertainties is not a scientific argument. These are rhetorical devices. It's hard to describe how pitiful they sound to a scientist, nor how dangerous it can be that people will buy into the rhetoric and idealogy because they can't tell science if it bit them on the posterior.

 

No measurement is perfect. Not one. Quantifying the errors in a measurement is part of how science is done. The presence of error in a measurement or model does not, in and of itself, mean anything about the validity of the science.

[Dr. Dalek]

In spite of the likelihood of an (unknowable) internally generated trend component, the model/observed data comparison presented here demonstrates that the observed century time scale global-mean temperature changes are consistent with a dominant anthropogenic influence and secondary influence from solar irradiance increases. The secondary nature of the solar role obtains because the overall solar forcing trend is substantially less than the central anthropogenic forcing estimate of 1.3 W/m2. The consistency of this explanation is reinforced by the magnitude of the residuals about the best fit, which is very similar to the magnitude of internally generated natural variability estimated independently from the GFDL coupled O/AGCM.

 

This consistency, however, does not prove that there has been a large anthropogenic influence. Given uncertainties in the forcing (both anthropogenic and natural), it is still possible that part of the trend has been internally generated. Because of these various uncertainties, estimates of the value of the climate sensitivity cannot be improved by using observational data alone; the range of possible values for Delta T2× deduced in this way is substantially larger than the standard model-based range for Delta T2×, 1.5-4.5°C. It is, however, much more difficult to derive sensitivities below 1.5°C from the observational data than it is to obtain values above 4.5°C.

 

Where do we go from here? In the most recent IPCC report (31) and in an earlier report (34), it was noted that studies of global-mean temperature alone are insufficient to show a compelling cause-effect relationship between anthropogenic forcing and climate change. Such studies, as shown above, can demonstrate that the observed warming is consistent with a substantial anthropogenic effect on climate but cannot accurately quantify this effect. To show a cause-effect linkage, more sophisticated techniques are required that make use of the patterns of observed climate change, either in the near-surface horizontal (latitude/longitude) plane (39, 40) or in the vertical (zonal mean/height) plane (41, 42). Such pattern-based studies have shown increasing and statistically significant similarities between model predictions and observed temperature changes. These results, combined with the evidence from global-mean analyses, provide convincing evidence for a discernible human influence on global climate; but further work is required to better quantify the magnitude of the human influence and reduce uncertainties in the climate sensitivity.

 

Here! These people agree with SkepticLances opinion quite clearly!

 

As for my own, I will emphisise the fact that they repeat in the text several times about the uncertainty about human and natural forcings.

The asertion that human forcings are dominant is in fact theoretical, here you see they say that climate trends are consistent with some predictions based on human and solar forcings but they also state that there is a likely that there is another natural trend force at work!

 

Proceedings of the National Acadamy of Sciences: http://www.pnas.org/cgi/content/full/94/16/8314

This also supports my asertion . . . .

How man kind may be effecting it is uncertain and subject to study and debate.

[doG]

If you don't understand how science is done' date=' you can't hope to argue, on scientific principles, why any particular conclusion is wrong. Misrepresenting statistics is not a scientific argument. Harping about the presence of uncertainties is not a scientific argument. These are rhetorical devices. It's hard to describe how pitiful they sound to a scientist, nor how dangerous it can be that people will buy into the rhetoric and idealogy because they can't tell science if it bit them on the posterior.

 

No measurement is perfect. Not one. Quantifying the errors in a measurement is part of how science is done. The presence of error in a measurement or model does not, in and of itself, mean anything about the validity of the science.[/quote']

Something you obviously don't understand about science. It is one thing to claim that something is a FACT and another to say that we theorize something. Claiming that man IS THE PREDOMINATE CAUSE is a claim that it's a fact and not just a theory. PROOF of a FACT does not rest on any uncertainties, assumptions or best guesses and science does not leap to conclusions based on such!

[bascule]

Claiming that man IS THE PREDOMINATE CAUSE is a claim that it's a fact and not just a theory.

 

You clearly have the scientific concepts of "hypothesis" and "theory" confused.

 

And furthermore, you're attempting to argue with a scientist about them.

 

If you wish, you can caveat that statement with "All evidence collected to date has lead the overwhelming majority of the scientific community to the conclusion that..."

[Dr. Dalek]

And furthermore, you're attempting to argue with a scientist about them.

Lets not get into that, as far as I have read none on this thred are climatologists, yet we all have a strong opinion about something involving climatology.

[doG]

You clearly have the scientific concepts of "hypothesis" and "theory" confused.

Your statement didn't strike me as a theory or hypothesis. You said, "Anthropogenic forcings are the primary cause". That strikes me as a claim of fact and you have not proven that to be the case. I know it's a subtle point but there's a difference between facts and theories in my book.

[bascule]

Lets not get into that, as far as I have read none on this thred are climatologists, yet we all have a strong opinion about something involving climatology.

 

It seems like the global warming naysayers have a very distorted view of what science actually is, and lack a basic understanding of scientific terms like "hypothesis" and "theory". They seem unwilling to accept any sort of uncertainty, and suggest information which can't be demonstrated experimentally is inherently unscientific.

 

Your statement didn't strike me as a theory or hypothesis. You said, "Anthropogenic forcings are the primary cause". That strikes me as a claim of fact and you have not proven that to be the case. I know it's a subtle point but there's a difference between facts and theories in my book.

 

Yes, it's a theory. Science typically doesn't "prove" things within the context of a formal logic system (and really, I can't think of when science has ever done that... proofs are something mathematicians can do inside the rigors of an environment consisting only of formal logic) Yes, there is a degree of uncertainty. Could they be wrong? Of course they could. However, all evidence amassed to date has been enough to outweigh any sort of scientific argument to the contrary.

 

Here! These people agree with SkepticLances opinion quite clearly!

[...]

http://www.pnas.org/cgi/content/full/94/16/8314

 

You seem to like highlingting any part of the paper that deals with uncertainty. There will always be uncertainty. Yet you seem to completely be ignoring the rest of the paper:

 

In spite of the likelihood of an (unknowable) internally generated trend component, the model/observed data comparison presented here demonstrates that the observed century time scale global-mean temperature changes are consistent with a dominant anthropogenic influence and secondary influence from solar irradiance increases. The secondary nature of the solar role obtains because the overall solar forcing trend is substantially less than the central anthropogenic forcing estimate of 1.3 W/m2. The consistency of this explanation is reinforced by the magnitude of the residuals about the best fit, which is very similar to the magnitude of internally generated natural variability estimated independently from the GFDL coupled O/AGCM.

 

This paper argues that anthropogenic forcings are dominant.

 

I'm still waiting for anyone to produce any peer-reviewed scientific paper arguing that natural forcings are dominant.