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Sceptics

Denial vs Good Science Part II

One of the seven graphs which Andrew Bolt claims end the warming hype
One of the seven graphs which Andrew Bolt claims "end the warming hype"

The next part in the Denial vs Good Science story comes from an exchange between Andrew Bolt and me in the Melbourne Herald Sun. Both articles appeared originally in the print version of the paper, but are now available online.

This is what Mr Bolt said:

Evidence doesn’t bare out alarmist claims of global warming

THESE are the seven graphs that should make the Rudd Government feel sick.

These are the seven graphs that should make you ask: What? Has global warming now stopped?

Look for yourself. They show that the world hasn’t warmed for a decade, and has even cooled for several years.

Sea ice now isn’t melting, but spreading. The seas have not just stopped rising, but started to fall.

Nor is the weather getting wilder. Cyclones, as well as tornadoes and hurricanes, aren’t increasing and the rain in Australia hasn’t stopped falling.

What’s more, the slight warming we saw over the century until 1998 still makes the world no hotter today than it was 1000 years ago.

In fact, it’s even a bit cooler. So, dude, where’s my global warming?

The full article, which you should click on and read now, is available here. This prompted the following response from me, published the next week in the Herald Sun:

Warm to sceptical science

YOU’VE no doubt come across a few opinion columns over the past year which claim that global warming has stopped. Or that we are heading into a new ice age.

Or indeed, that rising carbon dioxide levels have nothing to do with climate change – it’s all just natural causes.

Yet the great majority of news stories on the latest scientific findings say that global warming is accelerating.

Or that its impacts are happening faster than earlier predicted.

Or that spiralling industrial carbon emissions are pushing us ever faster towards climate disaster.

Pretty confusing, eh? Who, or what, to believe?

The key to navigating this minefield is to use a bit of sceptical thinking.

By this, I mean “sceptical” in the dictionary sense – doubt what’s told to you at face value, ask sensible questions, consider all evidence, and most importantly, to demand a consistent argument.

Once you become a real sceptic – something scientists are trained to be – the rest is fairly easy.

So just as a talking point, let’s ask some sceptical questions about a few of the graphs that the Herald Sun’s Andrew Bolt recently claimed should end the warming hype and make the Rudd Government feel sick.

I don’t have space to cover all seven graphs, but you’ll get the gist.

Andrew impishly asks: “So, dude, where’s my global warming?”

I might as easily respond with the question: “So, mate, what’s propping temperatures up?”

Read on here for the full editorial…

Incidentally, in the interest of space saving in tight column inches, they chopped out a couple of extra points I’d made:

… on the satellite data:

Even Andrew Bolt’s favoured satellite measurements of the lower atmosphere show that the hottest decade was 1999 to 2008 and that the decade before that was cooler, and the decade before cooler still. By the way, satellites don’t measure temperatures directly. They have to use a complex mathematical model to estimate temperature from radiation wavelengths, and account for the fact that the satellite peers through many layers of atmosphere and gradually shifts in its orbit over time.

… and my original conclusion:

The ‘greenhouse effect’ was discovered well over a century ago, and in 1896 a Swedish Nobel prize winning chemist, Svante Arrhenius, calculated by pen and paper that a doubling of carbon dioxide in the air would cause 5 to 6 degrees of global warming. He did this long before any noticeable warming had actually been observed. He also did it without computers. They just help us refine the picture.

The error Arrhenius made was in thinking that it would take 3,000 years of industrial output to cause this doubling of carbon dioxide. At current rates of carbon emissions, we look set to get there by 2050.

A response by Michael James was also posted in Crikey, Paul Norton at Larvatus Prodeo and by Jeremy of the Blair/Bolt Watch Project (with his own set of graphs, just to prove the point!). I’ve also responded to graph’s 1, 2 and 7 in my first seminar of Climate Change Q&A, available here and here [the rest will be considered in later presentations].

Now, naturally, I fully anticipated a reaction from Mr Bolt – after all, why bait the trap unless you plan to ensnare the prey? But the nature of the response – and not just from Mr Bolt – was really quite revealing about the way non-greenhouse theorists deal with criticism.

But that is the topic of Denial vs Good Science Part III.

By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

48 replies on “Denial vs Good Science Part II”

“Global Warming” is flat earth science. I mean that quite literally. Since the Professor is so sure of himself than I’m sure he won’t mind going through the whole model right from the start and auditing it for the plausibility of its assumptions.

We might start from the idea that a doubling of CO2 leads to a 1 degree increase in temperature for starters. And the allegation that this is derived straight from radiative physics.

Obviously there must be a host of simplifying assumptions for that conclusion to fly. We would wish to know what these simplifying assumptions are. They seem to be that the planet would be flat, twice as far from the sun, noon all the time, a black body, with the water vapour invariant and averaged out throughout the planet. But in any case I’m sure the Professor could throw some light on the simplifying assumptions no matter what they might be.

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Why don’t you have a go at auditing the model Graeme, since you are the one proposing the critique?

In terms of evidence for the relationship between GHG concentration, radiative forcing and equilibrium temperature change, the palaeo-record implies ~0.75C per 1 watt/m2 forcing. This, of course, includes all possible feedbacks, +ve and -ve, since it’s the real world over a long period of time, not a model or a short-term observation. Yet physics calculations of forcing very closely approximate this observed outcome, which gives confidence in the fundamental models. This gives a climate sensitivity (T change for doubling of CO2 concentration) of 3C, +-1.5C.

Add in surface albedo changes and other slow feedbacks, and you get another 0.75C/wm2, implying an overall sensitivity to doubled GHG forcing of 6C, see: http://arxiv.org/abs/0804.1126

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Because I think its just ridiculous for starters. Lets not run ahead of ourselves. We are talking about this 1 degree claim for a doubling of CO2. And the allegation that this generalization comes straight from fundamental radiative physics. We want to see the assumptions and aggregation needed to make this claim.

You can use high or low levels of aggregation. But the levels of aggregation here are something that people ought to know about. They won’t believe it coming from me.

Like I said they seem to imply at least SOME of the following:

“the planet would be flat, twice as far from the sun, noon all the time, a black body, with the water vapour invariant and averaged out throughout the planet. ”

Lets not play the slippery eel. We hadn’t got to your claim about the overall sensitivity (a bogus notion in my view). We wanted to deal with even the bipartisan assumptions. And this 1 degrees business appears to be bipartisan.

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So you are not capable of telling me the assumptions behind, what after all, is supposed to be a bipartisan notion of a 1 degrees change with a doubling of CO2? And instead the Professor sidesteps onto a ridiculous claim about sensitivity, then links to alarmists. Whereas you two mindless bullyboys start hassling my site.

Lets go over it again shall we. Now the claim that this 1 degrees for a doubling comes STRAIGHT from radiative physics simply cannot be true. There needs to be certain simplifying assumptions and certain aggregations to make such a conclusion work. What are these assumptions?

We ought to go over it and over it and over it again until you bully-boy advocates of the UN status quo actually understand the problem.

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[ I gave my warning in an earlier post. It was ignored. This final post was even worse, and has been deleted for abuse. I am a tolerant man and open to engaging with critics, but there is a line and you’ve crossed it. As such, Graeme Bird’s comments on this site are now suspended. I will not tolerate personal attacks on myself or any other posters. Go and vent your vitriol elsewhere.]

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You do the right thing in banning the remarks of those who use threats and personal insults in their postings. They obviously have nothing of any substance to add to a civilised debate on the science and will NEVER be convinced by peer reviewed scientific argument. They seem to believe that this is like politics or religion – unfortunately if they win this debate we will all ultimately lose, and our children and grandchildren most of all. Seems to me they are all frightened by the future scenario and just want it to go away so they can return to their safe, comfortable lives. We are all afraid – but some of us know we have to DO something about it not rail against the science.Keep up the good work Prof.

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Climate inactivists have been dancing the global temperature records dance for, well, quite some time. It usually goes like this:

“All the four major temperature records — GISS, HadCRUT, UAH, RSS — show that temperatures have steadily decreased starting from year X!” (where X is ridiculously close to 2008)

“In addition, the UAH records” — suddenly they decide to throw away all the other records — “show that temperature records have steadily decreased from year Y !” (where Y is further away from 2008) — “and this can be seen by drawing a straight line from the year Y data point to the 2007 data point and ignoring all the points in between!”

Repeat, repeat, repeat ad nauseam with different suitable values of X and Y.

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Brian and Barry ….re those graphs.

They do show that temperature, sea levels, ice sheets and CO2 levels rise and fall virtually in unison. What the question is which of these components cause the others to rise and fall?

To support the AGW theory one would automatically assume that CO2 is the culprit yet, from what I understand the oceans trap and release CO2 based on temperature. Therefore a rise in temp causes a rise in CO2.

Apparently CO2 levels fell last year in line with the drop in global temperature.

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To support the AGW theory one would automatically assume that CO2 is the culprit…

AGW theory requires no such thing. You need to learn what AGW theory *is* before you can overthrow it, I’m afraid.

I suggest you spend more time studying and less time writing posts that do nothing more than make your lack of knowledge obvious.

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Thanks for your articulate and intellectual response Dhogaza. You obviously spent hours coming up with a good technical response which is unusual, many supporters of AGW tend to just flame anyone who isn’t part of the program.

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i think on your podcast you said something about a maths degree or the like. well can you see a similarity with climate science and some number theory problems like FLT. all sorts of cranks get involved. you need one of those cards that a certain uni used to have. it read something like “thanks for your proof but there was a failure of logic on page __ line __ yours …….”. it was normally given to some honours student to deal with.

there seemed to be a simplicity with the problem that seemed approachable but we all know that wiles needed an 100 page proof for it. as wrong as many cranks like bolt or some of his winged monkeys are at least more people are thinking bout science and and are more involved with the steps along the way of an on going problem. this in the end should be good for science.

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WotWot Says:
18 August 2008 at 12.04

Evidence?

Wotwot …I was a bit hasty in what I said, basically it was late at night and I was shooting from the hip. Now that I have rechecked my source the fact is that for the first time in history the Mauna Loa Observatory has recorded a decrease in CO2 levels between January and July. Now I know that a swallow does not make a spring but this is the first time in history that this has happened and coincidentally it coincides with cooler global temperatures.

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Kimbo,

A link to a TV weather presenter’s blog is not evidence. Especially when that TV weather presenter is a non-scientist, immune to evidence and science. Watts, the author of the blog, just *knows* that AGW is false. Nothing shakes him from that belief, and any cherry-picked data point is used to ‘prove’ him right. He is some combination of liar and idiot, and every post he makes provides further evidence of it.

Why not go to the source of the data and get the facts? http://www.esrl.noaa.gov/gmd/ccgg/trends/ No sane, honest person can deny the reality.

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I’d like Bolt to explain why these graphs have tracked each other so well over the last 450,000 years. Surely he doesn’t think it’s all due to cosmic rays or sun spots!

Oooh, I missed that one, thanks Brian. I’ve added it to my post as it’s another good dissection.

Are you guys new to the subject of climate change?

I’m just curious because it is well known that temperature change occurred 800 to 1,000 years before CO2 change over the past 450,000 as shown in the ice core data. This was both on the warming from glacial conditions as well as the cooling from interglacial to glacial.

While this lag of CO2 change behind temperature change doesn’t disprove AGW it is certainly not support for it. If anything it teaches us not to jump to conclusions about causation simply because of correlation.

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Kimbo
Now that I have rechecked my source the fact is that for the first time in history the Mauna Loa Observatory has recorded a decrease in CO2 levels between January and July. Now I know that a swallow does not make a spring but this is the first time in history that this has happened and coincidentally it coincides with cooler global temperatures.

As shown by the raw data in the NOAA link provided by DavidONE, this small drop in CO2 levels is just part of the normal seasonal variation, it is not historically unprecedented, and the overall trend is still unarguably upwards.

Furthermore, if you are going to assert the validity of that close correlation (and presumably causal link) between falling CO2 levels and falling global temps, then you also have to accept a similar link between rising CO2 levels and rising global temps. So, according to your reasoning, if the overall CO2 trend is up, then so must be the global temp trend, and the rising CO2 must be responsible for it.

Do you accept that?

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This argument has been raised and refuted numerous times – in fact it shows very strong evidence for GHG amplifying the initial warming triggered, in that case, by solar forcing.

Could you point me to strong evidence for GHG amplifying the initial warming please? I’ve read quite a bit on the subject and I realize that is the most common theory… but is there actually strong evidence to support that? Or is that just the current theory since the lag was discovered?

Yes, the cycles captured in the ice cores very roughly match the orbital record. But changes in insolation, the the magnitude of the temperature change and actual climate forcings involved in these glacial to interglacial transitions are so poorly understood that I’m surprised someone has been able to find strong evidence of GHG’s role in these changes. I look forward to seeing that.

Your question is explained, in layman’s terms, here:
http://www.skepticalscience.com/What-does-CO2-lagging-temperature-mean.html

Interesting that you would choose that among the many sites attempting to address the lead/lag issue. I would agree with the author that the Gore movie oversimplified it, just as Brian did above. But this is an example of a correlation which is visually compelling but loses it’s impact when any audience is told that CO2 lags behind changes in temperature and not the other way around.

And unless you are going to surprise me with some very strong evidence for GHG amplifying the initial warming the more detailed explanation that author provided is simply the latest theory.

Also interesting here is that when the warm interglacial periods end and temperature falls CO2 can remain high for several thousand years. Again the orbital driven forcings are small, yet still overpower the elevated CO2.

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Just a question as a matter of interest, when considering the synchrony between T and CO2 what is the approximate error in the estimated ages?

And a second technical question, is it impossible for the tiny bubbles of air trapped in the ice cores to slowly migrate up?

Thanks.

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Error bounds are on the order of 3-6 centuries – it takes time for the fresh snow to pack down to ice. Once solidified to glacial ice, movement of trapped air bubbles is impossible.

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Re: JimR, #26:

The answer is well summarised here, and I quote:

CO2 as a feedback

The increase in CO2 and other greenhouse gases is a feedback of the temperature change. The increase is both a result of and cause of warming. Quoting from the earlier paper, “This sequence of events is still in full agreement with the idea that CO2 plays, through its greenhouse effect, a key role in amplifying the initial orbital forcing.”[1]

The skeptics say that this is backpeddling, as if scientists are straining to salvage the CO2/temperature connection. However, the amplifying effect of increasing greenhouse gases was predicted long before the lag was measured.

From this 1990 paper:[2]

“The discovery of significant changes in climate forcing linked with the composition of the atmosphere has led to the idea that changes in the CO2 and methane content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing and by constituting a link between the Northern and Southern Hemisphere.”

[1] Caillon, N., Severinghaus, J. P., & Jouzel, J. (2003). Timing of Atmospheric CO2 and Antarctic Temperature Changes Across Termination III. Science , 299, 1728-1731.

[2] Lorious, C., Jouzel, J., Raynaud, D., Hansen, J., & Le Treut, H. (1990). The ice-core record: climate sensitivity and future greenhouse warming. Nature , 347, 139-145.

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So in reality there is no very strong evidence of CO2 amplifying the warming but a theory has been put forward that GHGs amplified the warming?

Isn’t it circular reasoning then to show the correlation in the ice cores as if that was evidence of modern warming? We know CO2 (and CH4) were not the drivers behind the changes seen in the ice cores. They did increase and may have acted as a feedback, but the level of amplification is dependent on climate sensitivity. And of course climate sensitivity is something that is still unknown.

Graphs such as the ice core data we are discussing or temperature and CO2 since the industrial revolution show a visual correlation on the surface but the devil is in the details and neither is actual evidence of GHGs as drivers of climate. That doesn’t mean that GHGs aren’t climate drivers but it can hardly be called evidence.

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JimR – you can calculate the forcings involved. Orbital forcing by the solar trigger is ~0.25 w/m2. The rest comes from albedo flip and GHG release. If you want to know the full evidence, read this paper:

Hansen, J., Mki. Sato, P. Kharecha, G. Russell, D.W. Lea, and M. Siddall, 2007: Climate change and trace gases. Phil. Trans. Royal. Soc. A, 365, 1925-1954, http://dx.doi.org/10.1098/rsta.2007.2052

OR these two postings:

http://www.realclimate.org/index.php/archives/2004/12/co2-in-ice-cores/
http://www.realclimate.org/index.php/archives/2007/04/the-lag-between-temp-and-co2/

The 2nd one answers your straw man question at the end particularly well.

Short version: you simply cannot replicate the pattern of glacial-interglacial cycles without GHG forcing (as a feedback AND a forcing). It’s impossible. Yet with GHG forcing, you can match the observations of temperature based on oxygen isotopes extremely well. Strong evidence.

I suggest you do some further reading and thinking.

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Barry – you keep pointing me to blogs (that I’ve already read) but not answering the questions. Have you even read these things??? The Hansen paper focuses on how imprecise the measurements of lag are as if to dismiss the lag. It certainly doesn’t address the issue.

The first realclimate article only addressed the point that the lag doesn’t disprove current AGW theory. This is rather obvious and is an excellent example of a straw man logical fallacy. The author took on an obviously incorrect position and showed it had no merit.

There is no straw man in my post above and the 2nd realclimate article addressed my point but did not provide any answer. That article (actually the included reply to the letter from Jeff Severinghaus) only said to not focus on a single cause for these changes and because CO2 wasn’t the initial forcing it shouldn’t be ruled out as having a role in the change. It never answered the question of how glacial onset can occur up to 3,000 years with continued interglacial CO2 values.

As you note the initial orbital forcing is small (~0.25 w/m2) but the ice cores show us that CO2 levels have remained high for 1,000-3,000 years after glacial onset. Based on modern climate sensitivity estimates the climate forcing from CO2 alone (up from ~180 ppm to ~290 ppm) should be much larger than than the initial orbital changes. And I have yet to see a theory of how ice sheets grew to provide large albedo changes while GHG levels remained high.

The real question is – can the pattern of glacial-interglacial cycles be replicated with GHG forcing? And while this forcing helps as a feedback to explain the amplitude of these changes it doesn’t resolve the many outstanding issues of what drove these changes.

It is disingenuous to show such graphs as if they show the CO2/temperature relationship without revealing that CO2 is not the driver of the changes but a feedback or amplifier.

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cce is correct, go read AR4 chapter 6. Hansen explicitly addresses these forcings, the lag, and the explanation. And it was predicted before it was observed. So you obviously didn’t read the paper, or didn’t understand it if you did. Your “real question” is what I just answered.

But this could go on forever. So it won’t. You have been given the science JimR – multiple papers – and you choose not to believe it. In fact I’ve decided that if I’ve answered a sceptic here in at least 3 ways, and they blithely keep repeating the same question, then it’s time to move on.

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That’s fine, you keep sending me on wild goose chases when I ask questions so I won’t trouble you anymore. Good luck with getting to grips with the brave new world of future climate. At some point getting to grips has to involve actually answering climate questions.

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JimR,

When glaciation begins, CO2 is in equilibrium. Forcing from CO2 is therefore 0 because CO2 is not changing.

If orbital parameters change in such a way to keep snow on the ground longer, you get an albedo feedback that cools the planet. This, in turn, sets off other feedbacks (GHG decrease among them) that increases the cooling.

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cce,

That’s exactly the point. CO2 is in equilibrium with zero forcing as glaciation begins and well into glaciation, for a thousand years or more. CO2’s role is as a feedback.

So what would the graph of CO2 and temperature look like if CO2 wasn’t a feedback? (i.e. hypothetically not a GHG) While the amplitude of temperature would decrease without this forcing CO2 would still track temperature since it increases and decreases in response to temperature change. Regardless of CO2 being a driver, an amplifer or completely inert CO2 and temperature would track each other.

This is the folly of using these visual aids which show a correlation and imply a causation that is not there.

By the way, where in WG1 Chapter 6 did you see a reference to 1/3 albedo, 1/3 GHG, 1/3 aerosols? I see that aerosols are a fixed value in some models and the Chapter 6 FAQ listed those three forcings as three ways Earth’s energy balance changes. But aerosols seem to play a relatively small role.

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JimR

Previously, you asked:
“As you note the initial orbital forcing is small (~0.25 w/m2) but the ice cores show us that CO2 levels have remained high for 1,000-3,000 years after glacial onset. Based on modern climate sensitivity estimates the climate forcing from CO2 alone (up from ~180 ppm to ~290 ppm) should be much larger than than the initial orbital changes. And I have yet to see a theory of how ice sheets grew to provide large albedo changes while GHG levels remained high.”

The fact that CO2 “levels remained high” is irrelevent to the cooling brought about by albedo changes. If the albedo increases, the temperatures will go down even if the CO2 levels are high (but static).

The causation is there, but, of course, it is not the trigger. I personally don’t think the ice core CO2/temp correlation is a very good argument to make with skeptics, because if they don’t believe that CO2 causes warming, they won’t believe it is a feedback that causes warming. I do, however, argue with skeptics who say that CO2 doesn’t cause warming because warming comes first.

The various forcings are shown in figure 6.5. You are correct that aerosols are much less. The albedo changes from the ice and land is 1/3rd, GHG is 1/3rd, and aerosols and vegetation (also albedo) are 1/3rd when put together. My mistake.

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The causation is there, but, of course, it is not the trigger. I personally don’t think the ice core CO2/temp correlation is a very good argument to make with skeptics, because if they don’t believe that CO2 causes warming, they won’t believe it is a feedback that causes warming.

I don’t think the ice core CO2/temperature correlation is a good argument to make period. It’s not a matter of believing in the GHG properties of CO2. The causation is as a feedback so CO2 doesn’t change the shape of that graph. The Earth plunges into ice ages while CO2 remains high and the Earth warms while CO2 remains low. In it’s role as a feedback CO2 can only amplify the changes but not change the shape of the graph.

What those graphs show is that temperature drives changes in atmospheric CO2, yet those graphs are used to imply that CO2 drives the changes in temperature… which is false. It may contribute and amplify temperature as a GHG but it doesn’t drive the changes we see in those graphs.

I do, however, argue with skeptics who say that CO2 doesn’t cause warming because warming comes first.

Sure, the lead/lag issue doesn’t imply that CO2 does not cause warming but I have rarely seen anyone actually use that argument. What we see most often is someone touting the temperature/CO2 correlation in the ice core data as evidence of something it’s not. From AIT to this very blog the argument is made how close the correlation is between CO2 and temperature. The reality is that CO2 will follow temperature in a close correlation and because of it’s properties as a GHG CO2 can only change the amplitude of the temperature graph… it doesn’t impact the correlation. CO2’s GHG properties have nothing to do with the shape of the graph or how well temperature and CO2 track each other.

These facts don’t stop activists from showing those graphs and implying things that aren’t there. They make a strong visual impact… but a poor scientific argument. And unfortunately those in the scientific community only say that showing such a graph is an oversimplification.

The various forcings are shown in figure 6.5. You are correct that aerosols are much less. The albedo changes from the ice and land is 1/3rd, GHG is 1/3rd, and aerosols and vegetation (also albedo) are 1/3rd when put together. My mistake.

Keep in mind the level of scientific understanding on albedo is considered Low and aerosols/vegetation is Very Low. As was noted in Chapter 6 there is much to be learned and current models used on the LGM didn’t include aerosols or vegetation and had trouble reproducing some features of the LGM.

Thanks for the civil dialogue.

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The take away point from the ice cores and “ice ages” is that you can’t get temperature swings of that magnitude without the GHG feedback or the other feedbacks for that matter. However, since GHG doesn’t come first, then I agree that it won’t have any impact on “skeptics.” For everyone else, pointing out the role of GHG is just good education. I think the best way of summing it up without getting into “what came first” is to just say that GHG are responsible for about a third of the temperature change during glaciation and deglaciation.

An example of GHG leading temperature increase is likely the Paleocene-Eocene thermal maximum, but, given the uncertainties, I doubt if causation can be established to the satisfaction of skeptics.

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The take away point I see is that people generally focus on the correlation of temperature and CO2 over the past several hundred thousand years, which as far as I can tell you agree isn’t the story shown in those graphs. Mr. Gore in AIT focused on the “fit” of the two lines in the graph. Many other climate documentaries show the ice core temperature/CO2 graph and point out the correlation. Brian above pointed out how they tracked each other.

In order for this to be educational the point would need to be made that CO2 is a feedback and doesn’t impact the correlation seen in those graphs. That doesn’t happen. Other than discussions such as this we don’t hear the point that models only attribute 1/3 of the temperature change in those graphs to GHGs.

Above I said “It is disingenuous to show such graphs as if they show the CO2/temperature relationship without revealing that CO2 is not the driver of the changes but a feedback or amplifier.” I would agree with you that the are used for “just good education” if people were educated to the role CO2 is thought to have played… but they aren’t are they?

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It is accurate to say that there is a correlation between CO2 and temperature, and it is accurate to say that CO2 increases temperature. It is accurate to say that the occurance of ice ages and interglacials depend on CO2 and other GHGs. It is not accurate to say that CO2 triggers them, but no one says that.

I don’t think this is a good argument to win over skeptics since they don’t believe that CO2 influences temperature to any substantial degree, thus they won’t believe any CO2 feedback influences temperature. But for everyone else, it’s a good way of illustrating both the influence of GHG, and how “small” temperature swings (4-6 degrees) can radically affect the globe. I just wish people would close the door to these attacks by specifying that GHG don’t cause all of it.

In the case of AIT, if Gore had said (paraphrasing) “It’s a very complicated relationship and CO2 doesn’t cause all of the temperature change , but when CO2 goes up, temperature goes up” then that would have been perfectly fine.

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In order for this to be educational the point would need to be made that CO2 is a feedback and doesn’t impact the correlation seen in those graphs.

Well, actually, CO2 can be a feedback and a forcing. And climate scientists are perfectly aware of this, have been, blah blah. The only people who can’t seem to understand this simple fact are denialists like … YOU.

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Well, actually, CO2 can be a feedback and a forcing. And climate scientists are perfectly aware of this, have been, blah blah. The only people who can’t seem to understand this simple fact are denialists like … YOU.

The discussion is not about what climate scientists are aware of, but the use of certain graphs in public presentations and what the public is lead to believe by the use of them.

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