Observations Show Climate Sensitivity Is Not Very High

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.


Taking into account the logarithmic effect of CO2 on temperature, the 35% increase we have already seen in concentrations represents about 3/4 of the total forcing to be expected from a CO2 doubling. Since we have warmed about .7oC so far, we should only expect about .3oC more for a doubling from pre-industrial levels, so about 1oC not 3oC as the scientists predict. Clearly the climate model sensitivity to CO2 is much too high.


Even without addressing the numbers in this argument, there is a fundamental flaw in its reasoning.  We don't yet know exactly how much the climate will warm from the CO2 already in the air, there is a delay of several decades between forcing and final response.  Until an equilibrium temperature is reached, present day observations will not tell us the exact value of the climate's sensitivity to CO2.  The reason for this is primarily the very large heat capacity of the oceans. The enhanced greenhouse effect from higher CO2 levels is indeed trapping energy in the climate system according to expectations, but the enormous quantity of water on Earth is absorbing most of the resulting heat. Due to water's very high heat capacity, this absorbed energy shows up as only a very modest ocean warming, which in turn dampens the temperature change on land and lowers the global average trend.

This is commonly referred to as the climate system's thermal inertia. According to model experiments and consistent with data from past climate changes, this inertia results in a lag of several decades between the imposition of a radiative forcing and a final equilibrium temperature.

Now let's look at a couple of further details.  CO2 is not the only factor effecting the global temperature and in fact there is a phenomenon often called Global Dimming which is counteracting greenhouse gas warming.  Global dimming refers to the blocking of incoming sunlight by particulate pollution in the troposphere and airplane contrails in the stratosphere.  It is not a well quantified effect but it may well be masking a great deal more warming, definitely it is masking some.  

This is just one example, clearly an important one, of why we can not look at the temperature trends and pretend we can attribute everything to only CO2.  This same mistaken argument is made when looking at the mid-century cooling trend.

I believe it is Richard Lindzen who originated this argument, but it seems there is another problem as well, the numbers he is using don't add up.  35% increase in CO2 should correspond to 43% of the forcing from 2x CO2 (ln(1.35)/ln(2) = 43%) which is not 3/4.

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.

"Observations Show Climate Sensitivity Is Not Very High" was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.

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Coby claims: "Taking into account the logarithmic effect of CO2 on temperature, ..."

What formula is he using? As the temperature increases, the amount of heat radiated by a black body increases by the 4th power of the temperature. This is not a logarithmic relationship.

As the CO2 in the oceans increases, the water becomes more acidic. This make the water less able to absorb CO2. How does he take into account this effect?

As the water warms, it can hold less CO2. Where are the terms in his formula to take into account this effect?

As the oceans absorb CO2, the CO2 is locked up by Ca cations to form carbonates. There are a finite number of Ca cations and when they are gone, the rate at which the oceans can absorb CO2 will precipitously decrease. Where is this effect modeled in his formula?

Why is anyone taking this hand waving argument seriously? Does anyone think that the carbon cycles in the oceans and atmosphere can be modeled with a simplistic logarithmic relationship?

I do not. I think the effects and relationships are FAR more complex than Cody asserts. I would be very interested to see this formula. Why does he not back up his wild claim with THE mathematical model that would make climate science easy. Until he does so, I consider this claim to be so much spam.

Warm regards, Rick.

"Taking into account the logarithmic effect of CO2 on temperature"

This is about the only valid bit of his argument. The log law was first put forward by Arrhenius in 1895 and is sometimes called the law of global warming.

Realclimate argues that it is the worst way to determine the climate sensitivity by starting from twentieth century temperatures. As Coby points out the problem lies with the uncertainty involved with the aerosols (dimming). But it should have been at the top and not classified as a "further detail". It sinks the methodology because that way you can easily obtain any sensitivity whatsoever including an infinite one. Lindzen is perfectly aware of all of this and also of the inertia as can be seen from his writing. What he has done is to choose his data to get the result he wants (just what he claims is done by the modellers).

What if you reject Realclimate's position and follow Lindzen in trying to work backwards from the observed temperatures? You must allow for all the possible sensitivities and allocate them probabilities. One example is in Natalia G. Andronova and Michael E. Schlesinger,2001. J.Geophys.Res, VOL. 106, NO. D19, PAGES 22,605�22,611. They end up with a 90% probability that the sensitivity will lie between 1C and 9.3 C and a 54% probability that it will lie outside the IPCC TAR range (mainly on the high side). A corrected version of Lindzen would just consist of one point which might just get on to the the bottom of the range.

Of course Lindzen would argue that Andranova and Schlesinger must be rejected because it is based on a climate model. That leaves the way open for him to substitute his own back of the envelope model without any justification.

By Geoff Wexler (not verified) on 06 Sep 2008 #permalink

Reply to Rick.

The log law relates radiative forcing to concentration of greenhouse gas. Your comment diverts attention from this to all sorts of other non-linear effects which might be important at large warmings but which might be ignored to start with. The fourth power law due to Stefan Boltzmann is not one of them because it is essentially a linear relationship for the 'small' warmings we are discussing. Small here means relative to the absolute temperature of about 300K; it does not mean harmless.

As for the log law I suggest that you try Ray Pierrehumbert's theoretical book which is partly on line. I only have a bit of it at hand which includes a relevant remark :

"The logarithmic effect of water vapor is somewhat more difficult to cleanly quantify than is the case for well mixed greenhouse gases like CO2, but if one adopts a base-case vertical distribution and changes water vapor by multiplying this specific humidity profile by an altitudeindependent factor, one finds that each doubling of water vapor reduces OLR by about 6W/m2 (Pierrehumbert 1999)."

By Geoff Wexler (not verified) on 06 Sep 2008 #permalink

I would be somewhat more persuaded by this argument if, at the same time, an obvious consequence of this was considered. That is, the possibility that some or all of the current warming being due to the heat that was stored in the oceans due to the solar irradiance related warming in the early part of this century.

But this or any alternatives weren't even ruled out - apparently the ocean only releases heat ahead from now, it rather conveniently isn't releasing any at the moment from past warmings. Hmmm.

Don't get me wrong, I'm not saying it definitely was - I certainly don't know - but that isn't the point. The argument above is not science, it is a sales pitch.

Hi frank,

Don't forget that there are 60+ arguments in this guide they each have a very narrow focus by design so don't expect every aspect of the situation covered in every article!

You are quite right that we would expect a similar lag time from any forcing, including solar. Solar irradiance has not varied with any significance since around 1950, so I think is is quite reasonable to rule it out copletely as a contributor to the post 1980warming trend.

But this or any alternatives weren't even ruled out

Well, not by me in this article, but please refer to the extensive work cited in the IPCC chapter's on attribution.

(Chapter 9 from this page

I think it "quite reasonable" to rule out CO2 as the primary driver of temperatures, but I'm sure we can both agree that this is not an argument.

And anyway, really? I've heard of longer timescales than that being stored as heat in oceans (no reference for that unfortunately).

Solar irradiance has not varied since 1950? Hmm, not according to the IPCC report where fig 2.17 on page 190 shows a rise from around the turn of the century to 1950, then a dip about 1970, and then a rise to levels clearly (if not massively) higher than the pre-1970 levels. Let me think, I'm sure there's some other measurement relevant here that did something like that....let me get back to you.

That graph does not show what you describe, but it is not very suitable to your purpose anyway, it is on a very large timescale and does not have the 11 year solar cycle removed from it makeing it very hard to discern any trend. Why don't you check the sources cited at this article.

Another argument against solar dominance of the warming is the fact that the warming signal is greater at night than the day, consistent with an enhanced greenhouse effect but not with increased irradiance.

The graph I mentioned can be seen in here -


It is titled Total Solar Irradiance and the first line of the caption reads Reconstructions of the total solar irradiance time series starting as early as 1600, and so covers 400 years.

There are 9 cycles after 1900, covering the whole century. Looking at the newer Wang reconstruction, the peak of each of these cycles has the following values, each of these being the amount above 1365 W/msq.

0.7, 1.2, 1.0, 1.1, 1.4, 1.4, 1.2, 1.6, 1.7

The values of the nadirs of the cycles are closer together but follow the same trend broadly. The 1.2 is the dip I mentioned around 1970. The trend I described that you claim is hard to see is to me rather obvious.

Maybe you could explain you assertion that this graph does not show what [I] describe and is not very suitable to [my] purpose.

I examined the links on the page you suggested. The graph here


seems to be showing an increase in temperature of more than 0.8 degrees from 1900 to now. Ive never seen such a claim anywhere else.

And another of the links is to, erm, Wikipedia. So I was redirected from the IPCC report to Wikipedia.

People reading this can draw their own conclusions about the fact that the answer to so many questions on this site is to refer to the IPCC reports, yet you glibly suggested I go elsewhere when the IPCC data did not support your argument.

Lord monkton presented a paper to the american physics association. If you are at all mathmatically inclined I would suggest it as a read. It took me a while to work through the calculations, but Moncktons article really puts a hole in AGW theory that is tough to plug.

This paper is enough evidence to flip me to being a so called denier. What is the "how to talk to a climate skeptics" response to this?

By Don Simpson (not verified) on 10 Jan 2010 #permalink

This paper is enough evidence to flip me to being a so called denier. What is the "how to talk to a climate skeptics" response to this?

The paper wasn't peer reviewed, it caused great embarrassment to the APS, and it has been thoroughly debunked. I'll let you do the exercise of googling for competent take-downs.

Monckton has no formal background in science or math, and is a proven liar (among other things, he lies about being a member of the House of Lords).

Apparently your standards of evidence are quite low if you think a non-reviewed paper by a non-scientist somehow not only overturns the theoretical work of a very large number of scientists, but also a huge suite of observational evidence.

"Monckton has no formal background in science or math, and is a proven liar (among other things, he lies about being a member of the House of Lords."

No it wasn't peer reviewed in the formal sense, but the mathmatical equations have no flaws and the consultation in putting the paper together are the same thing as a peer review, minus the inherent bias. (BTW Monckton has a hereditary peerage)

Since climategate revealed the massive corruption within the peer review process, I'm not swayed by the arguement. I'm not concerned with someones credentials but more with the evidence.

Monckton unequivocally proves that C02 doubling will have a minor impact on global temperatures. The climate sensitivity and the effect of greenhouse forcing must be in doubt by now. Monckton raises a valid point, why should we do anything if the evidence points to a very minor greenhouse effect? If anything a minor forcing to the positive would be a good thing. (The 6 degree rise would not though)

I have looked at the attempts to rebuke Monckton online, they are very weak at best. Essentially the same arguements you raise which are baiscally "we don't like him, he's not part of our club")

If someone has a logical arguement as to why Moncktons math is wrong I'd love to hear it. But the arguements along the lines of "he's not a climatologist" are irrelevant.

By Don Simpson (not verified) on 10 Jan 2010 #permalink

Don Simpson, I don't think you tried very hard to get a critique of the discount monk's "paper".

Here is a critique by Arthur Smith an eminent physicist:


As can be seen, the question should be "what is right about the paper?" rather than "what is wrong with the paper?" since the former could be answered in a one liner whereas describing what is wrong with the paper goes on for page after page.

Why do all of you deniers continue to show your ignorance of science in such a blatantly obvious way? Have you no self-esteem? It is obvious that you know very little of physics, maths or climate science.

By Ian Forrester (not verified) on 10 Jan 2010 #permalink

thanks for the link, it's quite informative

From the "It's not as bad as we thought department"

-- New NASA model: Doubled CO2 means just 1.64°C warming --

'Important to get these things right', says scientist
By Lewis Page
Posted in Environment, 8th December 2010 13:24 GMT

NASA and NOAA used their more accurate science to model a world where CO2 levels have doubled to 780 parts per million (ppm) compared to today's 390-odd. They say that world would actually warm up by just 1.64°C overall, and the vegetation-cooling effect would be stronger over land to boot â thus temperatures on land would would be a further 0.3°C cooler compared to the present sims.

It now appears that the previous/current state of climate science may simply have been wrong and that there's really no need to get in an immediate flap. If Bounoua and her colleagues are right, and CO2 levels keep on rising the way they have been lately (about 2 ppm each year), we can go a couple of centuries without any dangerous warming.


Can I ask you a couple of questions regarding that study? First, did you read it? Second, why would you uncritically accept this particular paper as accurate, while rejecting the thousands of other papers that predict a much higher rate of warming?

I am going to go out on a limb here, and answer those questions for you:

1 - No
2 - Because it fits with my preconceived worldview.

Since you didn't read it, it is pretty disengenuous to try to make any claims about it. Its also dangerous. How often have you seen deniers make a fool of themselves by linking to things that they thought supported their views, only to have it pointed out to them that the paper says exactly the opposite of what they (and the denialist blogsite where they found the comments that they cut and pasted) thought it did.

So I will help you out by providing some ACTUAL information from the paper (yes - I have read it):

".....By accelerating the water cycle, this feedback slows but does not alleviate the projected warming, reducing the land surface warming by 0.6°C. Compared to previous studies, these results imply that long term negative feedback from CO2-induced increases in vegetation density could reduce temperature following a stabilization of CO2 concentration......"

".....A compilation of results from climate models of varying complexity indicates that in a 2 à CO2 environment, temperature would increase between 2 and 4.5°C, and rainfall would increase in most regions except the Mediterranean, the southwestern part of the United States, South Africa and Southwest Asia [Intergovernmental Panel on Climate Change (IPCC), 2007]. Results from these models also indicate that compared to their respective baselines, the global mean surface runoff would increase faster (8.9%) than precipitation (5%) [Nohara et al., 2006]. These assessments, however, did not allow vegetation leaf area index (LAI) to increase with CO2 and subsequent changes in climate. Increase in LAI affects photosynthesis, evapotranspiration, surface albedo and surface roughness, all of which feedback on climate....."

So the authors are assuming that climate change will increase the leaf area index of plants, and are basing their analysis on an increase in terrestrial vegetation. But as they say themselves, there are significant problems with this approach, and it contains a number of assumptions:

"......Our work bears resemblance to the studies of Betts et al. [1997] and Levis et al. [2000]; however it differs from them in the modeling approach:
[8] 1. As an alternative to interactive vegetation-climate we consider a controlled vegetation-climate interaction approach to quantify the negative feedback of vegetation to greenhouse warming.
[9] 2. We use a unique methodology that simultaneously accounts for down-regulation of vegetation physiology under 2 Ã CO2 and simulates growth in leaf density constrained by global satellite observations, only where vegetation is observed to exist and only where it was previously water limited.
[10] 3. We do not allow vegetation to migrate in these simulations.
[11] We postulate that the excess photosynthetic capacity and the additional water available following down-regulation would stimulate vegetation growth much more than previously suggested. This feedback results in a stronger vegetation response and may have implications for climate....."

One of the most obvious problems with this approach (apart from the stated limitations on water availability) is that if continue to deforest the planet, there will actually be LESS plant matter - not more. But, even IF all these assumptions are accurate, it will only work under very limited circumstances, as they continue:

".....Secondly and most importantly, there is recognition that even if CO2 concentration could be stabilized, much of the warming is yet to be realized. In transient simulations [e.g., Betts et al., 2007], as CO2 rises stomata respond almost instantaneously but LAI takes a long time to grow, so the warming effect of stomatal closure can take a long time to be offset by the cooling effect of increased LAI. On the other hand, equilibrium simulations, such as the one used in this study and those of Betts et al. [1997] and Levis et al. [2000], assume an equilibrium vegetation response in which the LAI is fully grown and at equilibrium with 2 Ã CO2 climate. This suggests that while increased LAI may not slow global warming significantly in the near term, its long term negative feedback could potentially reduce temperatures following a stabilization of CO2 concentration. These results indicate that the vegetation could partially reduce the greenhouse warming projections and that the influence is more pronounced in forest-dominated regions....."

So, to summarise:

IF the amount of plant matter increases, and IF water availability is not a problem, THEN once CO2 reaches equilibrium, the levels of warming may be offset over land by as much as 0.6 degrees C.

Not exactly what you thought huh?


You may also note that one of the major assumptions in the paper is that the amount of leafy matter will require an increase in available water, BUT, as they themselves note, the rate of run-off will increase at a greater rate than that of precipitation. This suggests to me that water will be LESS available, not more available.

Further, you will also note that the conclusion suggests that as CO2 (and temperatures) rise, plants undergo immediate stomatal closure, and LAI only rises later. The authors also suggest that stomatal closure acts as a positive feedback rather than the negative feedback from an increase in LAI. This means that plants will accelerate temperature rises in the short term, and will only reduce temperatures; 1) after CO2 equilibrium is reached, and 2) IF there is no more deforestation.

I am going to suggest that is not exactly encouraging.


So in summary what you are saying is that this paper is full of assumptions to the point where it is rendered useless, one wonders how on earth it passed peer review.


I am confused why you would even take any notice of the paper at all. It is based ENTIRELY on model predictions - and we all know what you think about models.

To be consistent, you should just reject it outright.

1- No, I read the summary, should the alarmist summaries be reversed too?
(you see, during the day, I actually have to work to reduce CO2 production, not just talk about it)

2- Because it was new.

Mandas says -
". . . But as they say themselves, there are significant problems with this approach, and it contains a number of assumptions:"

Mandas - So why would they write it? Please advise when this isn't the situation with speculation.


I can't believe all the nagging (what women do) about a paper like this, especially from NASA and NOAA?

It's exactly this type of behavior that makes alarmists look like kooks!

If you are to have any credibility with the average Joe, you will need to change.

I am still waiting for the glaciers in the Himalayas to disappear? Remember that great peer reviewed process? I think it was the IPCC.

So maybe you would like to define sources which are OK and not OK to present as news here.

Just list them for me, thanks.

So we have for now -
(those that are not OK)
4] from the discussion with Wakefield and according to Coby - any studies which use fewer than 17 points or interpolate data to places where there is no real data)
5] Well, that adds Hansen to the list, for NASA and interpolated data.
6] Journal of Geophysical Research (published Spencer, oops)

Crakar- you have any to add right off?

to either list is fine.

And remember - good news is no news

My interpretation of Mandas's point (as someone who read neither the summary nor the body) is that the authors acknowledge that their sensitivity prediction is contingent on a number of fragile assumptions. Thats good science, and thats why they published it; it belongs in the scientific discussion. It does not mean we can at this point throw out every prediction of higher sensitivity.

It's exactly this type of behavior that makes alarmists look like kooks!

Paul, I'm sorry, but some version of this has begun to emerge as your trump card defense whenever you don't like being taken to task. Somehow fit it into "alarmism" and then you're vindicated.

Out of curiosity, Paul, would you please define the word "alarmist" for purposes of future discussion? (And please don't say "You," in attempt to be witty; that answer was silly and evasive the first time.)

If you are to have any credibility with the average Joe, you will need to change.

Which, for all intents and purposes, Paul, means never criticize, which is whats going to happen when you cite SPPI as in the "Wakefield" thread and the abstract of an article that heavily qualifies its own conclusions. You can't just squeal "Hey, ease up the alarmism, man. I'm just an Average Joe."

I can certainly speak for myself in saying its a promise I can't make (never challenge), and I strongly suspect I speak for Mandas as well.


it's a news story and look where it went because it didn't pile on doom and gloom.

it's not about cricism.

like I said, add to the list of sources which may or may not be used.

like I said, add to the list of sources which may or may not be used.

Use any source you like, Paul, just be prepared to give an account on:

(1) the credibility and accuracy of that source;
(2) the extent to which you understand the implications, or lack thereof, of said source.

And as small, added favor for me, don't just find a way to fit the word "alarmism" into a non sequiter retaliatory comment when confronted with (1) or (2) or above. Or, alternately, if you insist on using the term, could you at least specifically and usefully *define* it?


For the average individual this subject cooling/warming/climate change is a yawner and we're possibly in the hottest year on record.

Why do you suppose that is?

Because well fed people are indifferent by nature, Paul--especially toward things that don't have any tangible or immediate impact on themselves.

And on Sept 10, 2001, terrorism was a "yawner". What we might call "alarmists" were trying to tell Condi Rice and other members of the intelligence community that Al Qada was on the verge of a major domestic US strike. Sadly, their message had no appeal to "Average Joes".

where do you get this stuff ? and all wrong to boot.

Why are you always saying the earth is flat and donkeys fly?

If you want to make an assertion by all means do it. If you choose not to defend it at that point it says something about your ability to do so.

On a tangent, you'd be proud of me, Paul: I'm reading Lott's *Freedomnomics*. Its already rife with weak arguments, but at least I'm coming to that conclusion from *reading* it.

maybe you'd like to share the weakest one?

Wrong blog, Paul, but suffice it to say he is lost in space on the economic analysis of schedules of penalties for criminals and behavioral implications. Its what happens when a die-hard economist attempts to impose his field's basic principles (reasonable enough as far as they go; don't get me wrong) where they have very little applicability.

But out of curiosity, have you read it?

nope, but I may pick it up now, thanks


Skip's point at post #22 is probably one of the most important pieces of advice that could be given to anyone who posts anything here (or anywhere).

You can link to, or quote from, any source that you like. But as skip succinctly put it, you should first actually READ what you are referencing (and you didn't in this case), and you should UNDERSTAND what is being said (and you didn't in this case either).

As I suggested earlier, to attempt to use a source to support your case when you have no idea what it is actually saying is both disengenuous and has a very high potential to make you look like a fool when someone comes along and DOES read your source material.

If you want to link to the SPPI or wattsupmybutt etc then go ahead. BUT...... make sure you read the ORIGINAL document that they are discussing (which can be difficult, because Anthony Watts is notoriously bad at providing links to original documents), and have some understanding of the science so you can make a rational argument when your source material is questioned (and it will be!).

The big problem with linking to such unreliable sources is that the science (in the case of the SPPI) is so fundamentally flawed and biased that it has no credibility whatsoever - your average first year science student could easily DISASSEMBLE (lol) the arguments.

boob, er, mandas,

I don't have a case. You do.

If someone can not put a summary together which makes sense when one reads it, then this goes to my point about kooks even more.

Look, if you're interested in the article, read it, if not, don't.
The source for the summary was here -

If you see SPPI somewhere, fine, I don't.

And they either quoted from the paper or they didn't.
Like I said, kooks.

Mandas in 18,

No need to get smart, i was agreeing with you and as you say it is purely based on models not one empirical observation of leaf size has been used to strengthen the validity or accuracy of the paper. This paper should have been rejected by the reviewers because it simply makes assumptions based on never before used methodologies.

Skip you said this is good science in 20 sorry but this is crap science and this is a good example of the problems science well climate science at least is facing. If all the crap science by wanna be's could be weeded out and just the good stuff left then this topic (AGW) would be much clearer.


There are heaps i could add but to make it simple just list all the sites that do not agree with the IPCC and if any scientist no matter how good they are speaks against the IPCC then you simply smear them by associating them with ID or water divining.

Here are some

Jo Nova
Danish meteorolgy institute (Arctic temps conflicting with GISS)
Peirs Corbyn
The list goes on Paul and i have run out of time....oh yeah RSS and UAH as they show a decade of little or no warming as opposed to GISS (see DMI)
and of course how could i forget Monkton.


Crakar, where on earth did you get the idea that UAH and RSS differ from GISS? Not from that idiot at WUHB I hope. Surely not from the little list that you presented above since that would show that they are all wrong too. If you actually look at the data, I know that is not what you deniers do, but you would look a lot smarter if you did once and again. Just look at the data presented here:


This shows the temperature anomalies using UAH and GISS data for the past decade. The two regressions are definitely rising and, good grief, they are even parallel.

Don't forget that the UAH data is produced by two deniers, Spencer and Christy.

So what do you have to say about being shown that your quote above is nothing but nonsense?

By Ian Forrester (not verified) on 14 Dec 2010 #permalink

Ok, I'm really confused here.

At post #14, Paul linked to a paper and prefaced that with the remark that AGW is not as bad as people think, and ended with the comment that we may have centuries before we have to worry about dangerous warming.

I then actually read the paper (unlike others), and showed that the paper was based on a lot of assumptions, some of which are highly questionable. You know - the sort of things you discover if you read a paper before offering an opinion on its supposed conclusions.

crakar threw his two-bobs' worth in and suggested the paper was worthless, and skip responded by quite correctly pointing out that nearly all papers have some level of underpinning assumptions, and the authors were right to list theirs (I agree 100%).

Then for some reason we descended into a discussion about who or what is considered valid sources of information (why??). Skip and I both pointed out that it is ok to link to anyone (yes, even SPPI (I never said you linked to them paul - just that you can if you wish)), but that you should first read and understand your source before linking to it and offering an opinion. Why this should supposedly be a controversial point I cannot understand.

So go ahead, link to whoever or whatever you want. But be warned. Someone, quite possibly me, will read just about everything you link to. No - that's a lie. I will NOT read the opinions of idiot denialist bloggers, but I WILL read the original peer reviewed work that they are commenting on (note to crakar - EVERYTHING produced by the SPPI is just idiot denialist opinion, they NEVER produce peer reviewed work).

And once I read the document, if it is apparent that you have NOT read the paper, and are just cut-and-pasting the opinions of a denialist who has misrepresented the work, or are basing your views on a paper ENTIRELY from what it says in a newspaper article, then I WILL take you to task over it. READ THE DAMN PAPER BEFORE COMMENTING!!!!! Why is that such difficult or controversial advice?

Mandas i did not throw my two bobs worth in (thats 20 cents for those that dont know) i simply responded to your post 18, i assumed you wanted a response.

In regards to making assumptions in papers i also agree 100% but there comes a point when the assumptions outweigh the facts at this point any conclusions made in the paper are useless surely you would agree with this?

I also understand the frustration you show when someone links a paper that does not fully support what they say it does, i should know as i have been caught a couple times myself. In pauls case he read the summary which "should" encapsulate the findings in the body of the text. If the summary states one thing but yet the body of text states another or the summary findings are based on mere guesswork as in this case then the fault does not lie at Pauls feet but at the authors and reviewers.

Most people do not have access to the entire paper so all they have to go on is the summary if the summary is misleading then this shows how bad the peer review process really is.


Assumptions don't outweigh facts - they are simply used when the facts are unavailable. Once the facts are discovered, they should replace the assumptions and the hypothesis retested.

There is nothing wrong with using assumptions - we use them all the time because it would be exceedingly rare if all the facts were known. However - and this is my problem with the paper in question - I believe SOME of the assumptions in this paper are rather tenuous, and probably will not come to pass; particularly the assumptions about the water cycle and the 'steady state' forestation. All the facts point towards lower water availability and increased deforestation. Consequently, although the paper is probably an accurate statement of what would occur IF the assumptions held to be true, I believe that is unlikely.

In so far as reading the summary goes, it is not nor has it ever been acceptable to just read the abstract and to then base an opinion or develop an argument on that alone. You might suggest that the abstract 'should' encapsulate the findings from the body of the text, but that is only partially true. The abstract cannot - and does not - fully explain all the methods and assumptions of a paper, and these are absolutely critical if you are critiquing a work. Here is the 'full' abstract of this paper:

".....Several climate models indicate that in a 2 à CO2 environment, temperature and precipitation would increase and runoff would increase faster than precipitation. These models, however, did not allow the vegetation to increase its leaf density as a response to the physiological effects of increased CO2 and consequent changes in climate. Other assessments included these interactions but did not account for the vegetation downâregulation to reduce plant's photosynthetic activity and as such resulted in a weak vegetation negative response. When we combine these interactions in climate simulations with 2 à CO2, the associated increase in precipitation contributes primarily to increase evapotranspiration rather than surface runoff, consistent with observations, and results in an additional cooling effect not fully accounted for in previous simulations with elevated CO2. By accelerating the water cycle, this feedback slows but does not alleviate the projected warming, reducing the land surface warming by 0.6°C. Compared to previous studies, these results imply that long term negative feedback from CO2âinduced increases in vegetation density could reduce temperature following a stabilization of CO2 concentration...."

Now this is accurate as far as it goes, because it gives an introduction to the study, explains what the authors did, and what their results suggest - which is exactly what an abstract is supposed to do. But it is a bit like reading the headline of a newspaper then thinking you know the whole story - you don't! You have to read the whole thing to understand the full picture, and I will keep saying that over and over and over and over again until you and others get it.

It is NOT an excuse to say that you don't have access to the whole paper. I am not sure about you, but I tend to work by the principle that I shouldn't form an opinion on something that I know nothing about, or to rely on others to give me my opinion.

If all you have is a summary, how about instead of forming an ill-informed opinion, you actually ask someone for more information. I - for one - would be happy to follow up a legitimate query for more information on something that has picqued your interest, rather than having to constantly argue how you (or anyone else) has simply got it wrong.

I also understand the frustration you show when someone links a paper that does not fully support what they say it does, i should know as i have been caught a couple times myself . . .

a noble admission.

Most people do not have access to the entire paper so all they have to go on is the summary if the summary is misleading then this shows how bad the peer review process really is.

Alternately, the person reading the summary is seeing things that aren't there because he really wants to see them.

Crakar, (and this goes to anyone in the forum), while I obviously cannot ethically link whole papers that I can retrieve from inside of the paywall, I can get abstracts and conclusions and make them available.

I have in fact done this before so don't feel shy about asking.

Looks like we are all in agreement here on a few points, i will take you both up (mandas, Skip) on your offer if and when the need arises.


Feel free.

Yes skip i do agree with you, vote 100/100

By Surgical Blog (not verified) on 13 Jan 2012 #permalink

The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change. Anthropogenic greenhouse gases (GHGs), which are well measured, cause a strong positive (warming) forcing. But other, poorly measured, anthropogenic forcings, especially changes of atmospheric aerosols, clouds, and land-use patterns, cause a negative forcing that tends to offset greenhouse warming.

By Sammy Osceola (not verified) on 10 Feb 2012 #permalink

Looks like the Bob Grant school of gotchas has a disciple. The above appears to be from a Hansen paper - from 1998. I wonder how much better the accuracy has been determined in the last 14 years?

" and land-use patterns, cause a negative forcing that tends to offset greenhouse warming."

pfff. if burning all the forests and creating millions of methane farting livestock offsets lowers temps then it must be bad as temps are still rising. end sarcasm. you can draw a level line from a high point in the graph to prove no warming over the last 16 years if you want, but when you pan out you will see all the lower steps you've drawn before.