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What we agree on 

One of the interesting moments from the Cambridge conference was where Dr Eric Wolff of the British Antarctic Survey tried valiantly to find a measure of agreement between the two sides. I didn't get the details written down, but Dr Wolff has kindly recreated what he said at the time for me, for which many thanks are due.

In the table below, Dr Wolff's summary is in the left hand column and my comments are on the right. Blank implies broad agreement.

*Everyone in the room agrees that CO2 does absorb infrared radiation, as observed in the lab


*I think everyone in the room agrees that the greenhouse effect (however badly named) does occur in practice: our planet and the others with an atmosphere are warmer than they would be because of the presence of water vapour and CO2


*I'm not sure if everyone agrees that the effect does not saturate with increasing CO2, but we heard a very clear presentation about that from Francis Farley

Professor Farley's explanation was to imagine CO2 as being like ink poured into water. You can add more and more ink and so there is no end to the extra absorbtion you can get. Saturated absorbtion bands are a red herring. This assessment made sense to me.

I've set up a separate thread because I imagine some people will want to discuss this.


*It seemed that everyone in the room agreed that the CO2 concentration in the atmosphere has risen significantly over the last 200 years


*Almost everyone in the room agrees that this is because of anthropogenic emissions (fossil fuels, cement production, forest clearance).  We did hear Ian Plimer arguing that volcanic emissions of CO2 are more important than most scientists claim, but he did not explain why they would have changed in a step-like fashion in 1800, after tens of thousands of years with no such changes; and even he agreed that some of the increase in CO2 is anthropogenic.

This is not an area I've ever questioned, but I'm looking forward to finding out more from Ian Plimer about his ideas. I'm not sure I understand Dr Wolff's reference to 1800 either.

***I then suggested that if we agree all these statements above, we must expect at least some warming.  


Then moving to whether we already see effects:


*I think everyone in the room agrees that the climate has warmed over the last 50 years, for whatever reason: we saw plots of land atmospheric temperature, marine atmospheric temperature, sea surface temperature, and (from Prof Svensmark) ocean heat content, all with a rising trend.
(I briefly touched on the idea, mentioned only by Dr Howard in his introduction, that warming has stopped since 1998.  I used the analogy that it was very warm over Easter, but then cool enough that I had to scrape my car the following week.  But we did not take this as evidence against the idea that we are on a warming trend into summer, in which we know that July will be warmer than June than May than April, etc.).

Yes, but I would like to get some idea of whether the warming we have seen is statistically significant. i.e. a response to Doug Keenan's article in the WSJ



I think Lucia's work has shown fairly clearly that the trend since the start of the century is very unlikely under 2deg/century, so the analogy is not a good one.

*We probably don't agree on what has caused the warming up to now, but it seemed that Prof Lockwood and Svensmark actually agreed it was not due to solar changes, because although they disagreed on how much of the variability in the climate records is solar, they both showed solar records without a rising trend in the late 20th century.

 I didn't take this on board at the time. It would be interesting to see Svensmark's opinion. If the warming really cannot be shown to be statistically significant, how important is this kind of attribution?

*On sea level, I said that I had a problem in the context of the day, because this was the first time I had ever been in a room where someone had claimed (as Prof Morner did) that sea level has not been rising in recent decades at all.  I therefore can't claim we agreed, only that this was a very unusual room.

 Not something I know much about, but Morner's concerns seem important. I find the idea that we can't see the adjustments to the data disturbing.

*However, I suggested that we can agree that, IF it warms, sea level will rise, since ice definitely melts on warming, and the density of seawater definitely drops as you warm it.


*Finally we come to where the real uncertainties between scientists lie, about the strength of the feedbacks on warming induced by CO2, with clouds a particularly prominent issue because they have competing effects that are hard to quantify.  I suggested to the audience that we could probably agree that the likely range of warming from a doubling of CO2 was 2-4.5 degrees C (which is actually the IPCC range).  This was the first time I really got any dissent, so I then asked whether we could all agree on at least 1 degree (implying no positive feedbacks at all, even from increased water vapour and sea ice loss).  I got one dissenting voice for that, but there wasn't a chance to find which of the preceding statements he had disagreed with (it would be necessary to disagree somewhere up the line to be consistent with dissenting on this one).

I'm very uncomfortable about the idea of making a prediction about temperature when it is so likely that there is something missing from the models - this seems the most plausible explanation for the temperature trend since 2000/1.

Under the scientific method, shouldn't we find out what this is before we start testing again?

We may be able to agree that the no-feedback warming is 1 degree C, but there is a great big unknown in the shape of the feedbacks. The idea of overall positive feedbacks seems unlikely to me, given that the Earth's temperature doesn't seem to have got out of control in the past.

So there you go. Quite a lot of agreement on the basics, but some pretty interesting differences kicking in one we get on to the detail of what it means. We can discuss the agreement or otherwise in the comments. If I get some time I might put together a survey to get a better idea of how strong our agreement or disagreement on Dr Wolff's points is.

I also thought it would be interesting to see if we can get a measure of agreement on some sceptic talking points too. A couple of mainstream scientists I met at Cambridge have agreed to take a look at the specific points I raise above - namely the question of whether the warming in the temperature records is statistically significant and to what extent Lucia's work shows that the IPCC models have overstated the warming. I have discussed Lucia's work with a couple of other scientists since, and neither seemed to have strong objections to her work, although they were disinclined to place much weight on the results.

Underlying both of these areas is a simple question of whether the variability in the surface temperature records can be described with an AR1 model. Doug Keenan seems to me to have shown quite conclusively that it cannot (Doug's technical background document is required reading on this subject).

So my question for climate scientists would be this:

"Do we agree that the AR1 assumption for surface temperatures is inappropriate?"

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Reader Comments (160)

Regarding Dr Wolf's

Regarding the idea that the “temperature increase stopped in 2000”: my point is that we know there are natural variations

The supposed natural variations only cool the earth, dont they? So it is always AGW,...natural variations...AGW...AGW...natural variations.

We think we have an mechanism to explain how warming should occur, so every warming that occurs is due to what we can explain.

May 25, 2011 at 11:39 AM | Unregistered CommenterShub

I think I put this up above - but it is always worth repeating just to show more context and the precipice we are on -

May 25, 2011 at 11:44 AM | Unregistered Commenterlapogus

Eric and Bart, thanks for taking part civilly. Bart, you cite a bunch of papers, of which I looked at a few. Here's a quote from, a paper by Hansen and Sato:

"In contrast, atmospheric CO2 during the Cenozoic changed from at least 1000 ppm in the early Cenozoic to as small as 170 ppm during recent ice ages. The resulting climate forcing, as can be computed accurately for this CO2 range using formulae in Table 1 of Hansen et al. (2000), exceeds 10 W/m2. It is clear that CO2 was the dominant climate forcing in the Cenozoic."

This is what I said above: large fluctuations in temperature in the past are attributed to CO2 as prime cause, amplified by various positive feedbacks. Many climate-consensus people believe that the existence of such positive feedbacks is incontrovertible, and if pressed, argue that since we have no other possible model to explain the changes, it must be CO2. Sceptics would like a little bit more evidence that CO2 can spark off the feedbacks, and point out that the empirical evidence that it does so is not all that strong.

The Dana Royer paper in PNAS,, does the same thing: finds CO2 and temperature at some point in the past, attributes all warming/cooling to CO2 as the prime cause, and concludes that sensitivity must be big.

Here's a thought: if a fairly small change in forcing due to CO2 is considered large enough to set off a huge cooling or warming, why are small changes in other forcings (perhaps ones that are not known or well understood - e.g. Svensmark) not considered to be able to do the same thing? So how can we be confident in attributing these large prehistoric changes in temperature to CO2? And another question: do we really understand how the feedbacks work, are we really confident that talking about sensitivity as a single, constant property, is a sensible thing to do?

May 25, 2011 at 12:06 PM | Unregistered Commenterj


So you judge a piece of work not on its merits, but on the merits of another piece of work?

May 25, 2011 at 12:10 PM | Unregistered CommenterPhillip Bratby

Eric Wolff

I want theory, evidence and proof/disproof. Where is it?

And don't talk about models. I've worked with models. We had to fully validate them against empirical data before we could use them. We didn't use unvalidated models to change the whole of society's future.

May 25, 2011 at 12:14 PM | Unregistered CommenterPhillip Bratby


Doing some very physics and maths and finding that the Venusian and the Earth temperature at the same pressure agree in the absence of the greenhouse effect when you simply use the stefan boltzmann law along with solar flux could be (i) a new result that thousands of practising physicists have never noticed before (ii) a lucky result based on incorrect reasoning and which therefore allows erroneous conclusions to be drawn.

As the author seems to be a numerologist, it makes me wonder about explanation (ii).

May 25, 2011 at 12:40 PM | Unregistered CommenterFred Bloggs


Paleo reconstructions are all very nice, but is that really all you have to support your estimates of CO2 sensitivity? The period of rapid CO2 change for which we have by far the best observations is obviously the most recent one, and yet during the period when CO2 concentrations have increased by 35%, the increase in temperatures has been very modest, and is likely explainable in large part by other factors (UHI, black carbon, land use changes, maybe solar influences etc). What is more the correlation between CO2 and temperature has been rather weak, with the initial period of rapid CO2 rise coinciding with a cooling period (1945-75), and the most recent 15 year period showing no warming despite rapid CO2 increases.

While your estimates will no doubt vary, it seems from the available data that a one third rise in CO2 levels can have been responsible for no more than, at most, 0.4C rise. How this can be reconciled with your proposed sensitivity in the IPCC range is very puzzling, and not really adequately answered by paleo studies of distant epochs. Data on these periods in the distant past is very patchy, and with extremely poor timescale resolution - after all the Vostock ice cores looked pretty convincing until the time lag was noticed!

Noting that recent observations contradict your hypothesis is not arm waving, it's how science is done.

May 25, 2011 at 12:41 PM | Unregistered CommenterPeter Wilson

It's good to see that Dr Wolff is trying to establish common ground and join in the discussion here. I would agree with most of his points, but not no. 3.
There certainly is a saturation effect, as explained very clearly by Peter2108 at the bottom of the first page of comments, and you would expect saturation to be approached exponentially as Peter says. If you paint a window black to keep the light out, then add more layers of black paint, it soon has no more effect.
Now, on this page, Dr Wolff seems to be changing his story, and abandoning the ink argument in favour of something about the top of atmosphere. I do not believe that what goes on up there, representing a minute fraction of the atmosphere by weight, and the part furthest from us at the surface, has such a crucial effect on the Earth's surface temperature.
Even if the log rule is accepted, that is stilll a kind of saturation since more and more carbon has less and less effect.

Dr Wolff should also take care with his presumption that the sceptics commenting on this blog are less qualified than he is! It is ironic that the most convincing explanation of the log rule that I can find on the web is from sceptic physicist Lubos Motl.

May 25, 2011 at 12:55 PM | Unregistered CommenterPaulM

Just in case anyone thinks they are addressing me with their remarks:
I thought this might indeed be a chance for a civilised discussion, and some of the respondents seem happy to have that. However there are also a lot of remarks on here that are frankly rude and aggressive, and I won't be returning. Now I remember why I hate the blogosphere.

May 25, 2011 at 1:03 PM | Unregistered CommenterEric Wolff

However there are also a lot of remarks on here that are frankly rude and aggressive, and I won't be returning. Now I remember why I hate the blogosphere.

You have never been to Realclimate then, the comments here are very mild in comparison and no-one here is censored for having a different view, unlike Realclimate. And these are the guys you are defending.

May 25, 2011 at 1:12 PM | Unregistered CommenterBreath of Fresh Air

Mac, Neil,

Eric Wolff is correct when he wrote that "a positive feedback implies amplification, but not a system out of control; this is only the case if the sum of the gain factors is greater than 1."

Mac: Please re-read Eric's second last paragraph about expertise. It's relevant to your stating that
"As any engineer would know..." before trying discard domain knowledge or in this case nomenclature.

See also about the meaning of positive feedback in climatology.

May 25, 2011 at 1:15 PM | Unregistered CommenterBart Verheggen

@ breath of fresh air
Funny to see you say that. I did not see Eric Wolff "defend anyone". He was talking about facts and science. But I guess he feels attempting to do that is a mistake.

On the basis of your response I think he is right.

May 25, 2011 at 1:18 PM | Unregistered CommenterMarcusB

H2O : phase diagram and related spectroscopics of it are very complicated as is the dynamics when you have a mix of it. Same same with CO2 really but the latter its interesting behaviour is at a bit higher pressure and colder temperature.

New CO2 applications are coming . There are for example new washing machines that will clean making use of the mixing fluid H2O-CO2 at a couple of bar.

The cost is in the higher pressure, which is why I think you should share the costs(tighten seat belts here is my new Heath Robinson communal washing machine)
What you should do is build in any new appartment development a paternoster washing machine. you drill a 50m deep hole in the cellar , and fill it up with water, then you install the whole construct. The upper stages is where the apartments are , so when you need a washing you open the drawer in your app and quickly a put in a bag with your dirty clothes and some H2O and CO2 in the appearing box. the whole thing cycles through and below due to the high pressure you have liquid CO2+H2O with thorough cleaning effect. Up goes the thing and when your box arrives you hear a "ding!" , like a microwave. Now quickly fetch your washed belongings.


May 25, 2011 at 1:19 PM | Unregistered Commenterphinniethewoo

if you are a late responder to the "ding!" because you were in the john or something, you can always call the old lady living at the top floor and ask to fetch it when it appears and bring it down to you. That way she also feels valuable , and it improves soshul coheshun, as well.
Big society, what!

May 25, 2011 at 1:23 PM | Unregistered Commenterphinniethewoo


Small changes in other forcings *are* considered to be able to do the same thing as a forcing due to CO2 concentration change would.

Unknown forcings are not considered (how could they?).

Re Svensmark, even assuming an upper limit to ion induced nucleation, his theory could not explain a substantial fraction of 20th century warming. See eg the part based on Pierce et al 2009: The change in cosmic rays over the 20th century is “far too small to make noticeable changes in cloud properties based on either the decadal (solar cycle) or climatic time-scale changes in cosmic rays.”

You'd need a hell of a fudge factor to make it important, if even under the ‘ion-limit’ assumption that all ions go on to form a new particle, the effect is still negligible.

May 25, 2011 at 1:42 PM | Unregistered CommenterBart Verheggen


Now we have a new and completely different definition of postive feedback applicable only to climate change.

It really is quite remarkable. Postive feedback alone does not, never has done, and never will imply amplification and stability.

Positive feedback, without a restraining or stabilising force, applied to any system, be it mechanical, chemical, electronic, and dare I say climatic, will result in oscillation and eventual satuation of that system, e.g. a runaway effect.

The geological record clearly shows no examples of any runaway effects. Even climate scientists reject that notion for this planet.

It is clear that some scientists don't know the difference between climate change and climate instability, that really is quite a remarkable state of affairs.

May 25, 2011 at 2:06 PM | Unregistered CommenterMac


May I put this simple as I can, stop confusing positive feedback with closed loop system gain.

May 25, 2011 at 2:34 PM | Unregistered CommenterMac

There are things people agree on and there are things people disagree on. A third important category is things that people overlook. Two things in this category leap to mind:
1) Assessment of the beneficial effects of possible global warming. Arrhenius dreamed that global warming would be largely beneficial. A June freeze in the corn belt of the USA would be devastating.
2) There is an overemphasis on modelling the effect of CO2 in the atmosphere while largely disregarding the refinement of our understanding of the movement of heat in the oceans. For starters, one cannot predict a sea level rise without somehow accounting for and understanding the enormous pool of cold in the deep oceans. What scientists call the surface temperature of the earth varies by as much as 10 degrees C depending on whether you consider deep ocean temperatures or not. If ocean currents are changeable their effect on climate would likely surpass the effects of CO2.

May 25, 2011 at 3:51 PM | Unregistered CommenterHankHenry

for the 1st 10m of earth water surface, 300 M sq km, 3 * 10 ** 15 cb m you have good mixing of the water with the atmosphere (wind, storms, tides) and CO2 is in gas phase mostly.

there is about 3 g CO2 per liter dissolved and a degree warming (of the water, not the air) will deplete that to 2.9 g, which will be released in the air.

So that means 3* 10** 17 g CO2 will go in the atmosphere = 3 * 10 * 11 ton = 300 giga ton will be released.

There is now 3000 giga ton CO2 in the air giving 400 ppm CO2
So this extra 300 giga ton would give an extra 40ppm

0.1 oceans warming degrees => 30 gigatonnes CO2 (4 ppm) this is substantial, similar to the yearly Indonesian peat fires, which do not get any attention at all, . and 3 times more than our yearly fossil fuels burning.

May 25, 2011 at 4:14 PM | Unregistered Commenterphinniethewoo

Thought this might be of interest.

Quote, Dr Eric Wolff, Sept, 2006, "Ice cores reveal the Earth's natural climate rhythm over the last 800,000 years. When carbon dioxide changed there was always an accompanying climate change"

This is an example of positive feedback, a reinforcing, that if real would lead to climate instability.

What the ice core data actually shows is that it is temperature that drives concentrations of atmospheric CO2, and there is lag between CO2 and temperature.

Importantly, we know from the same ice core data that there is good relationship between rises in and temperature and corresponding rises in CO2. However, when temperatures drop away signficantly there is no signifcant drop in CO2. Atmospheric CO2, at concentrations that should have had a significant impact on climate, remain for considerable periods of time ....... but the temperatures continue to plunge.

There is no postive feedback, we still have climate change but not climate instability.

The funny thing Dr Eric Wolff would know this, because all this was known prior to 2006.

Instead from the same BBC article we have this from Dr Eric Wolff, "The ice core suggests that the increase in carbon dioxide will definitely give us a climate change that will be dangerous"

May 25, 2011 at 4:39 PM | Unregistered CommenterMac


Same word, different meaning in a different context. What's your problem?

May 25, 2011 at 4:44 PM | Unregistered CommenterBart Verheggen

Thanks for your reply. About Svensmark, and the link you provide, with all due respect to the author of that item, my instinct is not to take things that realclimate write as being gospel truth - though I don't believe they are necesssarily wrong either, unlike some commenters here ;-). So I'm not sure that it is a 100% done deal that it cannot provide a large enough forcing. Leaving that aside, though, the subtext of my question remains: can we really be confident that CO2 is the prime mover? As in, 100%, or 90%? And do we have good understanding of the feedbacks, again, to 100%, 90% or even 50%? As Mac at 11:17 and some others have pointed out, the modern empirical evidence in favour of strong feedbacks in response to CO2 is not all that great, especially when you do not allow yourself the deus ex machina of anthropogenic aerosols here and there.

Eric: a shame you thought we were all too rude. I've had pretty tough comments made to me in referee reports on my papers. Are you not used to academic debate being a bit aggressive at times? Also, you - perhaps not individually, but as a loosely affiliated member of the consensus for which you cannot resign all responsibility, are trying to tell the whole world what to do. That's very different from doing research on an arcane topic that the man on the Clapham omnibus doesn't care about. It brings with it kudos - but also responsibility, i.e. it exposes you to a bit of snippiness. Is that not fair?

May 25, 2011 at 5:14 PM | Unregistered Commenterj


For someone who has experience in designing 2nd order control systems I have no problem.

The problem is all yours.

May 25, 2011 at 5:14 PM | Unregistered CommenterMac

Dr Bart,
Maybe ask Peter Sinclair for a crock on this : he must know about control system theory.
He knows Aaanything..

May 25, 2011 at 5:21 PM | Unregistered Commenterphinniethewoo

If the brainees @ realclimate were so confident about what they wrote, they would sometimes set the blogging moderation levees lower..Alas they never do. Tellingly.

Even The Urinagad's "Kommentar macht Frei" blog has its spells where they let non-libtardo posts on for longer than an hour when it is not too detrimental to their labour union narratives.

May 25, 2011 at 5:31 PM | Unregistered Commenterphinniethewoo

I think that the change in temperature over the last century has been small so how could it be significant.I also think that thermometers were designed to measure local climate,why should we try to join them together to give a global temperature when we have satellite data for that.I am not sure about anything to do with so called climate change so how could I agree to anything about it.I am sure that the truth will become clear eventually as we continue to make observations.

May 25, 2011 at 5:41 PM | Unregistered Commenterdon penman

I thought the CO2-temp lag was established and Algore proved wrong, how come we have perfessors still debating this? maybe they have new data/theories since recently?

A stiff drop in temperature will make life difficult for the airborne CO2 molecules to dive back in the ocean (this allthough they'll want to as per solubility-temp characteristic): There will be less mixing of air with water. As it is cooler there will be less precipitation / storms /waves, and there will be more pack ice for longer times.

The dynamics of it all seems complicated i think diffusion must control how fast these things happen.
certainly re calthrates and liquid-liquid concentration transport.

May 25, 2011 at 5:55 PM | Unregistered Commenterphinniethewoo

linear systems theory (fourier, again) is pleasant enough but loses out when your system is non-linear.
but first thing you do is chopping a non linear system into more limited spaces where they are linear.
everything is linear enough when you're a bigot, like me!

May 25, 2011 at 6:00 PM | Unregistered Commenterphinniethewoo

Bart Verheggen

I also want to thank you for your comments and the links above --

Regarding cosmic rays as a possible driver, Nir Shaviv in a 2005 JGR paper made sensitivity estimates for past and modern climate changes with and without cosmic rays, and concluded that a lowish sensitivity was feasible given the cosmic ray effect. Judging from comments on his blog last year, I've little doubt that he would still defend his position assertively - as I imagine would Svensmark and the others working in this area.

It seems as if almost everyone working in the field does accept the basic AGW propositions (GHE, human emissions driving C02, warming expected) and so do I. But by itself this consensus seems to be only a little help to the poor politicians. On the questions of critical interest to them -- as well as many other scientifically interesting ones -- I can see only arguments between experts. I think the fact of such dispute needs explanation, as does the level of certainty in their views expressed by many of the scientists involved in it.

I'm not a climate expert myself, but have worked in academic theoretical physics research in the past and have come across similar disputes (although obviously nothing on this scale or visibility). From this, the explanation would be found in the fact that researchers are nearly always advocates for a scientific viewpoint (and are quite likely to remain so until the evidence in favour of the alternative becomes inescapable). What is your take?

BTW, I also noticed Curry picking up on the Bishop's post and I agree with her comments there.

May 25, 2011 at 6:05 PM | Unregistered CommenterPhilip


satellites are the best as long as we discuss phenomena after 1997 or something
before there is no global satlite cover

but a warmist is in a pickle then, as, when you only take 1997-2011 satellite data, there is no global warming.

so that's why they throw in historic data from when there were no satellites.
so then you hv to enter the fetid dungeons of UEA CRU or NASA Goddard where the cooking pots with historic temp data are burbling

May 25, 2011 at 6:06 PM | Unregistered Commenterphinniethewoo

Here's one I never see addressed. The consensus position (as represented for example by the IPCC Fourth Assessment Report) says that solar radiation may have increased by 0.12 W/m² since 1750, compared to 1.6 W/m² for the net anthropogenic forcing.

In the tropics there is a change of 5 W/m2 in reflected energy for each 1% change in cloud cover.

So I look at a tropical cloud cover graph

... and it seems the decrease in tropical cloud cover in the last 20 odd years alone blows the 1.6 W/m² net anthropogenic forcing out the window, completely demolishing the 0.12 W/m² "solar increase". I wonder if Trenbeth counted this in his "missing heat" sums.

May 25, 2011 at 6:08 PM | Unregistered CommenterFrosty

What a load of butterflies from Eric Wolff.

In all likelihood he doesn't have the time to be here, answering to questions, and perhaps there are many claims being stated here that he strongly disagrees with, drawing him in much against his inclination.

Which is all completely fine really - not everyone can really participate in blog stuff - for various reasons. And I think this is completely understood by many here, who said as much to Wolff.

Instead, Wolff says this is all 'rude' and tries to take his leave!

I've seen the same thing with many other scientists as well - they've to have the last word. The blogs are a rude place, Dr Wolff. It takes a bit of effort to make some useful contribution. You cannot do drive-bys and expect the plebes to line up for the tumbling pearls of wisdom.

Contrary to what you might have to say about the blogs, atleast for one, I dont mistake scientists' blogging ability to have any bearing on their scientific merit. Best wishes.

May 25, 2011 at 7:46 PM | Unregistered CommenterShub


I take it that you saw that I wrote the RC article about particle nucleation and its link with climate/cosmic rays as a guest post.

But surely you shouldn't take anything as gospel truth; I don't and I think the world would be better off if fewer people would rather than more.

As to how sure are certain things: I think the more relavent question to ask is what's the risk?

May 25, 2011 at 8:12 PM | Unregistered CommenterBart Verheggen

Btw, I think Wolff made a lot of good points in his long comment upthread. Bishop, what about featuring as quote of the day his following paragraph:

"I freely admit that I am not an expert on all, or even most, aspects of climate. When I reach a topic that I have not previously studied, I go to those who are experts, either in person or by reading their work. I maintain scepticism about some of their conclusions, but my working assumption is that they are intelligent and that they have probably thought of most of the issues that I will come up with. Can I observe as an outsider to the blogosphere, that it surprises me that so many people, presumably mostly with even less knowledge and training than me, seem absolutely convinced they have mastered every area of climate science."

I highlighted Wolff's list and his comment at my blog:

May 25, 2011 at 8:15 PM | Unregistered CommenterBart Verheggen

I've no doubt BH will let you start writing his blog when you let him write yours.

The circumstances of Wolffs departure from comments here were unfortunate, and I am glad that I have not contributed to this thread.

His last sentence is unfortunate too, in that it points to the sceptic pseudo-polymaths and ignores their opposites on the other side of the floor.

May 25, 2011 at 9:06 PM | Unregistered CommenterBBD

I think we can all agree that Dr Eric is a climate sheep in wolf's clothing.

May 25, 2011 at 9:43 PM | Unregistered CommenterMac

This is a good quote

but my working assumption is that they are intelligent and that they have probably thought of most of the issues that I will come up with

Didn't Sir Paul Nurse come across this issue on the recent Horizon show? Scientists are human and can make mistakes, and trust can sometimes be misplaced.

May 25, 2011 at 9:45 PM | Unregistered CommenterAtomic Hairdryer

Wolf he left allready and i hv not had the chance yet to insult him up a bit, this is not fair.

ah well, there is always BV..

What is particle nucleation?

May 25, 2011 at 10:23 PM | Unregistered Commenterphinniethewoo

" working assumption is that they are intelligent and that they have probably thought of most of the issues that I will come up with."

I also think that is a good quote because it was my attitude towards the announcements about Man-Made Global Warming; most people are busy with their own interests and commitments so have to take quite a lot on trust.

At the time the UEA CRU emails became available I was working at a company involved in commercial statistical modelling of client data, and I could see that the CRU methods would not have been acceptable there; that removed my trust in the unbiased expertise of the MMGW announcements and it's been 'show me the evidence not the models' ever since.

I mention this because I don't understand how a scientist can read what those emails reveal about peer review in climate science and not query MMGW bias or predetermined agenda, regardless of any praise for intelligence or experience.

May 25, 2011 at 10:47 PM | Unregistered CommenterDerekP

Yeah, our friend Eric left, using our words to make up the mind that was already made up.

In blog comments, everyone's going to come across as more belligerent than they are. One has to internally calibrate for that - it is an occupational hazard. That does not automatically mean that everything scientists have to say is being outright rejected. By the same token then, the Realclimate gang and Joe Romm sound wildly aggresive about climate findings. So does it mean then, that the science they push is on just as sure a footing?

More than a month ago, Bart Verheggen's own blog hosted a thread "Extinction, biodiversity and climate change" where Jeff Harvey a former editor at Nature held forth at length in what finally became an acrimonious debate on species extinction rates, the Amazon rainforest and the 'functions of ecosystems'. Harvey lashed and slashed with the same kind of logic as Eric: "why don't you trust the experts, you stupid, denialist morons?" Yet, three days ago comes out a paper in Nature magazine which reports in detail on how extinction rates (which are derived from computer modeling to begin with) have been grossly overestimated, and Stuart Pimm the originator of the earlier methods is fuming away on his blog, waving his fists.

So, I'll rather have an acrimonious debate with a scientist and be called a "denier" than stand in line to be patted on the head by an expert.

May 25, 2011 at 11:19 PM | Unregistered CommenterShub

they try to make you feel guilty shub , the warmists are far from being the sweethearts they proclaim.
Just think of AlGore's "an inconvenient truth" or the Peter Sinclair crocks on Dr Bart's site.

if there is anything that limits a bit species extinction it will be increased plant life on earth: extra CO2, extra heat, and more water circulation.

May 26, 2011 at 1:02 AM | Unregistered Commenterphinniethewoo

Hello All,

I've just been looking at this thread. As I said at the time, I really appreciated the interest that the contributors showed in my research and the polite discussion. It is enjoyable, and I think productive, to engage in this sort of debate. My own impression is that the overall tone of this thread is a bit different.

Shub, you say above that "In blog comments, everyone's going to come across as more belligerent than they are. One has to internally calibrate for that - it is an occupational hazard." But does that have to be the case?

You can hope that people let pointed and personal attacks just wash over them. But it changes an enjoyable experience to a rather unpleasant one. And then people who may have valuable and interesting things to say decide to leave the conversation.

This blog thread was entitled "what we agree on". It was designed to foster a discussion between two groups. In this context, I personally think that a polite discussion would be more interesting and productive than, a belligerent one...


May 26, 2011 at 7:14 AM | Unregistered CommenterEmily Shuckburgh

Emily, I agree that polite discussion would be good. Unfortunately, too many us have tried to have polite discussions at Realclimate, and we are all aware how far politeness extends over there. Is abuse politeness?

May 26, 2011 at 7:47 AM | Unregistered CommenterPhillip Bratby

Emily, a point I made to Eric above is that scientific debate also sometimes gets rather vigorous, and indeed unpleasant at times. We get used to that - and indeed in some way can be happy that the topic we're interested in can be of enough concern that other scientists can get (over)passionate about it. I've had some really terrible referee reports over the years. Have you and Eric not experienced that? True, some of the aggressive comments in blogs come from people who are less well informed than peers doing refereeing (though reading some referee reports you might doubt that...). I guess, as Shub says, that not all people are obliged to enjoy blog debates, but on the other hand, Eric would be wise not to think that just because some people were a tad vigorous with him we are all automatically wrong about everything. And if he and you find this blog uncivil, you should see blogs like the Guardian's Comment is Free (with rudeness on both sides, especially the consensus side).

Bart, yes, I had spotted it was you (hence my genuine but tongue in cheek "with all due respect to the author of that item"). My point is this: the little I know about particle nucleation and growth (and I do know a little bit, it is examined by scientists working in fields not a million miles from my own) is that it is not well understood. Knowing the slant that the IPCC have on things, I can then see that the error bar they put on their iconic 'forcing' graphic for "Total aerosol" (FAQ 2.1 Fig. 2 p. 136) might be a little bit too small - and perhaps the assigned value not quite negative enough. As to risks: well, again, us sceptics know that e.g. the Stern report's attempt to carry out cost/benefit analyses was rather, let us say, disingenuous about the rate of discounting that it used to try to convince us that spending trillions now would be the cheapest thing to do.

May 26, 2011 at 8:45 AM | Unregistered Commenterj

I disagree that fudging conversations makes them more meaningful.
There is no evidence for that.

Hitler was quite pleasant in smalltalk.

May 26, 2011 at 9:02 AM | Unregistered Commenterphinniethewoo

lots of couples exercise the right now and then to let the china fly across the room.
that's when the truth is found out.

Not when they are at a banquet celebrating the achievements of the free NHS or something

May 26, 2011 at 9:04 AM | Unregistered Commenterphinniethewoo

I've had bad experiences at RC too, but I still agree with Emily. The rudeness and censorship at RC is obvious to anyone who visits there, and it hinders them in getting their arguments across. It's easy to let irritation show, I've done it myself, but always get the most satisfaction in the end from being polite and constructive. If RC censor polite comments and questions then it is their loss – it is usually easy to find the desired information elsewhere.

Having said that, I'd like to take Bart's question "the more relavent question to ask is what's the risk?" in a straightforward way and agree with him and actually go a little bit further - if the only risk in using or not using fossil fuel was to climate, then surely no reasonable person would object to giving it up immediately. But that's not the situation we find ourselves in, is it? The solutions proposed to climate change have their own costs and risks, and these are not only economic and societal, but environmental as well. The point about risk is that all of the factors need to be rationally assessed and synthesised. When this is done mitigation solutions become far less attractive.

May 26, 2011 at 9:04 AM | Unregistered CommenterPhilip

From the Independent; "Global warming? It doesn't exist, says Ryanair boss O'Leary"

O'Leary "The climate has been changing since time immemorial. Do I believe there is global warming? No, I believe it's all a load of bullshit."

Dr Emily Shuckburgh, of the British Antarctic Survey "Over tens of thousands of years, the orbit of the Earth about the Sun slowly varies, and with it the amount of solar radiation that reaches the Earth's surface. When the orbit is such that the radiation dips low enough, it triggers an ice age. Since the Earth has not suddenly jumped into a different orbit in the past century, a different mechanism must explain the recent increase in global temperatures."

O'Leary "It used to be global warming but now, when global temperatures haven't risen in the past 12 years, they say 'climate change'."

Dr Shuckburgh "It is wrong to say global warming has stopped in the past 12 years. The weather changes day to day, and even when the temperature is averaged globally and over a full year, there are still considerable variations from year to year. When this is taken into account, no reduction is found in the global warming trend of 0.15-0.20C per decade."

O'Leary "There's absolutely no link between man-made carbon – which contributes less than 2 per cent of total carbon emissions, most of it is naturally emitted – [and] climate change."

Dr Shuckburgh, "Vast amounts of carbon are exchanged each year back and forth between the land, oceans and atmosphere – some 200 GtC/yr [GigaTons of Carbon per year] are naturally emitted and 200 GtC/yr are naturally reabsorbed. Man is now emitting more than 8GtC/yr, about half of which remains in the atmosphere. The impact has been significant. Before the Industrial Revolution, carbon dioxide levels were about 280ppmv [parts per million by volume]. Man-made emissions have increased that to nearly 390ppmv."

O'Leary "The same [scientific] community was telling us in the mid-1970s the world was heading into a new ice age. I mean, it is absolutely bizarre that the people who can't tell us what the weather is next Tuesday can predict with absolute precision what the global temperatures will be in 100 years' time."

Dr Shuckburgh, "Of course it is not possible to predict with precision the weather in 100 years. But we can characterise – to within a range – the long-term climate trend that underlies the chaotic weather."

O'Leary "The IPCC [Intergovernmental Panel on Climate Change] is a load of utter tosh."

Dr Shuckburgh, "The facts are that errors in the IPCC's fourth assessment report were identified and acknowledged, and the fundamental findings of the report were unaltered. This valuable scrutiny has strengthened, not discredited, the conclusions."

O'Leary "The only [IPCC economic growth scenario] that gives rise to this inexorable rise of man-made CO2 emissions linked to climate change... is 7 per cent compound economic growth into infinity. That's already been torn up in the last two years. We've already had a worldwide decline."

Dr Shuckburgh, "Carbon emissions do not have to rise inexorably for there to be climate change. If we stopped all emissions now, which is impossible, the temperature would increase for many years due to the emissions we have already made. Moreover, current CO2 emissions, even with the global recession, are in the mid to upper range of IPCC scenarios."

People my take issue with the answers given by Dr Shuckburgh, or indeed the personality that is Michael O'Leary, but it is the context that is more interesting. Here we have a mock debate that has been characterised as a Q&A between a swivel-eyed, slavering at the mouth, climate denialist monster and a calm, assured, rational and intelligent climate scientist.

That is how these climate ideologues see us and see themselves.

I leave the final words to Michael O'Leary, "Do I believe there is global warming? No, I believe it's all a load of bullshit. But it's amazing the way the whole fucking eco-warriors and the media have changed. It used to be global warming, but now, when global temperatures haven't risen in the past 12 years, they say 'climate change'."

May 26, 2011 at 10:39 AM | Unregistered CommenterMac

I tried to point out earlier in this thread (May 25, 2011 at 6:05 PM) that for many of "us", the problem in accepting the need for mitigation lies in the arguments between the climate experts evident as soon as you go beyond the basics.

I was hoping Bart might be able to offer some insider comment on the origin of these arguments. I haven't seen anything from him yet, but maybe Emily can offer some thoughts?

May 26, 2011 at 11:09 AM | Unregistered CommenterPhilip

Bart since you highlighted Dr Wolf's support of alarmism not because he knows the facts but because he says of them "I maintain scepticism about some of their conclusions, but my working assumption is that they are intelligent and that they have probably thought of most of the issues that I will come up with" may I point out that that is inherently saying that sceptics aren't intelligent & haven;t thought through our position.

I trust you will agree that that is far more rude and in a shotgun spread, fact free way, than anything anybody here said about him Feel free to suggest he should apologise. Personally I don''t mind since I have had far far worse said about me on "green" sites from realclimate on down, always without any attempt to produce facts. It seems, correctly, that we are expected to retain a far higher standard of decorum than our opponents.

A more fact based working assumption would be that the alarmists are saying what they are because they are being paid to. As you wil know not a single scientist, worldwide, who is not being paid by government supports the catastrophic warming scare. Elementary statistics prove that it is mathematically impossible for this to be coincidence.

May 26, 2011 at 11:32 AM | Unregistered CommenterNeil Craig

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