Michael Mann and Gavin Schmidt
Much in the spirit of the Fraser Institute’s damp squib we reported on last year, S. Fred Singer and his merry band of contrarian luminaries (financed by the notorious “Heartland Institute” we’ve commented on previously) served up a similarly dishonest ‘assessment’ of the science of climate change earlier this year in the form of what they call the “NIPCC” report (the “N” presumably standing for ‘not the’ or ‘nonsense’). This seems to be making the rounds again as Singer and Heartland are gearing up for a reprise of last year’s critically…er…appraised “Conference on Climate Change” this March. Recently some have asked us for our opinion of the report and so we’ve decided we ought to finally go ahead and opine. Here goes.
The fact that the very title of the report summary (“Nature, Not Human Activity, Rules the Climate“) itself poses–at best–a false dichotomy is not an auspicious start. The fact that the fonts and layout are identical to the real IPCC report is another indication that this isn’t quite on the level (and reminiscent of the infamous fake PNAS paper that accompanied the first ‘Oregon Petition’).
Reading the table of contents, the report has eight chapters (in addition to an introduction and conclusions chapter). Five of these, quite remarkably, have titles which are simply untrue. The remaining three chapters pose loaded questions which are disingenuous and misleading, if not outright dishonest, with ‘answers’ provided by the authors. In fact this is such a massive regurgitation of standard contrarian talking points and discredited canards, it’s obvious that reviewing this would be a herculean task (which is presumably the point – if you can’t convince people with actual science, bludgeon them).
However, precisely because most of these points have been made before, there exists a large body of work pointing out the flaws already. So instead of regurgitating these counterpoints, we will simply link to an index of these rebuttals. As some of you may know, we have a set up a resource to do precisely this; the RealClimate Wiki. Let’s see how this works…
Chapter 2 “How much of modern warming is anthropogenic” throws out the standard, itself now discredited, “the hockey stick is discredited” claim, and adds in the old favorite “CO2 doesn’t lead it lags”. We also get ‘observations and model predictions don’t match’, ‘the warming doesn’t coincide with the greenhouse gas increases’, and of course ‘the instrumental record isn’t reliable’. Naturally, we were a bit disappointed not to encounter the granddaddy of all contrarian talking points, But they predicted global cooling in the 1970s!.
On to chapter 3, “Most of Modern Warming is Due to Natural Causes”. The short answer to the title of the chapter is, of course, “ummm, no, its not”. The chapter draws in equal parts from the twin canards that its all just natural cycles, and ‘its the sun!.
If you’re growing impatient for model-bashing, no fear; there’s a whole chapter for you (Chapter 4: “Climate Models are Not Reliable”), which offers up the usual mix of straw man descriptions of how climate models actually work, and red herrings about supposedly missing feedbacks and processes. Fortunately, RealClimate wiki provides some one-stop rebuttal shopping.
The falsely-titled chapter 5 (“The Rate of Sea-Level Rise is Unlikely To Increase”) rests upon incorrect claims that sea level rise projections are exaggerated, and or that the IPCC supposedly lowered their projections of future sea level rise. Chapter 6 (“Do Anthropogenic Greenhouse Gases Heat the Oceans?”), if we take it literally, asks a rather embarrassing question (‘No grasshopper! The greenhouse gases are ‘gases’. They heat the atmosphere and surface and a warmer atmosphere transfers some of that heat to the ocean below. You still have much to learn.’). Chapter 7 (“How Much Do We Know About Carbon Dioxide in the Atmosphere?”) answers the question it asks with the usual nonsense about how the increase in CO2 is probably natural, or that we can’t trust the CO2 record, and that CO2 isn’t rising as quickly as projected anyhow. And chapters 8 and 9 offer the requisite disclaimer for contrarians that, even after you’ve debunked everything they’ve said so far, and come to the inescapable conclusion that anthropogenic climate change is (1) real, and that (2) future changes will be profound if we continue with business as usual, ‘it will be good for us anyway’..
In concluding, We’d like to level with our readers. Some of us thought that the “NIPCC” report was so self-evidently nonsense that we shouldn’t even give it the benefit of any publicity. But it does give a great opportunity to give the RealClimate ‘wiki’ a test ride. We hope to expand this resource in the future, and we’d actually welcome some additional outside help. (In fact, much of it is already due to some dedicated volunteers. Thanks!). So if you have a desire and the time to help organise this effort, drop us a line and we’ll set you up.
Chris, you refer to
https://www.realclimate.org/index.php/archives/2008/08/north-pole-notes-continued/#comment-97284
You _still_think_ you were all alone in your opinion?
But later in that thread you said you’d go look at Stoat — haven’t you done that yet? Look at the sea ice bets.
It’s not that you’re alone in thinking — you just aren’t getting support because you make clear that you’re not reading what people suggest you read.
Here, make it easy: Google for “arctic sea ice” +bet +Stoat
Chris, Under the “about” section on the front page you will find:
“RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists. We aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary.”
Climate has to do with long-term trends, not month-to-month changes. Most of us are here to learn, not to pontificate. That is, after all the stated purpose of the site. So, when you come on here pontificating about short-term trends and claiming on the basis of extremely weak evidence a reversal of trends, or that there is no trend at all, you should not be too surprised if your efforts are not well received. It is not your dissent from mainstream climate science that is the source of this, it is the flaws in your logic and the irrelevance of your post to climate issues that is to blame.
Dismissing long-term trends as a “moving average” while trying to draw conclusions based on a couple of months doesn’t really strike me as an approach likely to catch on in climate science.
Re: #93 (Chris)
Why are you fixated on the “prior moving average”?
This is not my basis for any statements about trend, and I’ll bet it’s not anybody’s. I never use the “prior moving average” and I rarely use moving averages because there are far better smoothing filters.
For trend analysis, I don’t use smoothing filters at all.
If increasing ice over 2009/10/11 mirrored 2006/5/4, I would analyze whether their data could or could not plausibly be due to noise superimposed on the existing trend (note: existing). If not, I would conclude that the data had departed from that trend with statistical significance, so the trend must have changed. The fact that the “prior moving average” continued to decline is irrelevant. If the trend does change next year, that doesn’t negate its existence this year — despite your claim to the contrary.
Claiming that it’s our basis for trend statements is nothing but a straw man. It’s especially reprehensible since your statements give every indication that you’re woefully ignorant of the subject. You really have no idea what the basis is — but you continue to pontificate on the topic even though you haven’t even bothered to ask.
#95 c.f. http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg
#99 “That didn’t happen…” Yes it did I’m afraid, for area as well as extent.
Compare the area line to the mean line for 2007 and 2008 at:
http://arctic.atmos.uiuc.edu/cryosphere/iphone/iphone.currentarea.series.html
(It appears to be down at the moment, but I would also link to http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic )
“….it refroze from a more scattered ice pack to start with. It wasn’t technically a stronger refreeze, but something like a quicker extent consolidation…”
There was an element of this in early-to-mid September which made the earlier refreeze than in 2007 seem even earlier re: extent. From mid-to-late Sep both area and extent appear to have been consistently 1 to 2 weeks ahead this year.
And my original argument was implicitly in relation to the autumn re-freeze, which means it is already fair to conclude it has been decisively vindicated. (If the fleeting peripheral ice of late winter fails to extend as far out into the Pacific, for example, early next year, resulting in a lower maximum, re-freeze will still have been early and strong in the context of the original discussion.)
#86 Nick – thanks, sincerely. I only just spotted your post. I’ve got enough faith in humanity that a part of me hoped someone would say something along the lines of what you said. I accept much of AGW theory too, for what it’s worth.
OK I’ve got serious amounts of study to do. Need to take a longer break from posting. Meanwhile, I’m feeling inspired by the striking alignment of the crescent moon, Venus and Jupiter – which I’ve now got a great view of through my window. Keep an open mind guys.
Oh I forgot to deal with this one:
#80 Wayne. Yes the St Roch had reached the Bering Strait by 27th Sep 1944. (Having left Pond Inlet http://tinyurl.com/6n3bee
no earlier than Aug 12th)
http://www.ucalgary.ca/arcticexpedition/larsenexpeditions
And what was my original point – that 2007 did not surpass 1944 in terms of overall ice extent? Not at all: summer 2007 clearly had significantly higher Arctic temperatures, and significantly less ice in the Arctic as a whole than summer 1944 – that’s not in dispute. (Though the size of the differences may be)
My original point was that cooler temperatures on all sides of the Arctic in 1975-1985 as compared with 1935-1945 seem inconsistent with graphs showing a 2 million km2 reduction in summer ice between the 2 periods. So to dismiss my point in the style you attempted, you would need to have produced maps showing that *in the mid-1980s*, the St. Roch would not have “…found itself in a battle against the ice as it tried to reach Bering Strait…”
Captain, do you think you would have won a similar battle against the ice in 1984 or 1985?
http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=09&fd=15&fy=1984&sm=09&sd=15&sy=1985
(bearing in mind these maps don’t even show concentrations of less than 30 per cent, and that “Compared to the powerful icebreakers which ply Northern waters today, the St. Roch was a frail and underpowered little ship.”!)
I see that Chris #68 is following in the footsteps of the Heartland Institute and has been trained well.
I “Know” that the first time the entire parry channel has been open to navigation from ships other than Icebreakers was in 2007. So I looked up the statement about Larsen.
Let me relate what one article I found states
“On its westward passage, Larsen took the St. Roch on a different route. Through the Parry Channel to Banks Island, the ship turned south through the Prince of Wales Strait and out into the Beaufort Sea.”
Now I’m not Arctic navigator but I can read a map. Larsen did not pass Banks Island on the Parry Channel but on the Prince of Wales Strait.
Yet more disinformation passed in a very sly way which will pass a very cursory inspection.
If you dig further you will find that it took Larsen 2 years to make the Eastern journey through very heavy ice and was forced completely out of the water on more than one occasion.
If you dare to look a little further you will find that in the 1944 trip he got into severe difficulty after making the NW passage run and the ship was nearly destroyed in the storms and ice.
During the worst of the Ice melt in 2006, Both Moscow and Istanbul were experiencing their worst weather in living memory. Note “Weather”.
As was stated earlier, if Chris cannot differentiate between weather variability and Climate trends, then he should desist. In fact IPCC has predicted severe weather events, both cooling and warming, driven by Climate Change. Clearly Chris does not read IPCC reports well.
There are much more interesting links like this one
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg
Which show clearly that far from running away in cooling mode, in fact the ice regrowth is slowing down and coming much closer to 2007
or the trend chart
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
Which does not actually match the figures reported for 2008 area but Even with that anomaly is still WAY below anything we can call normal since detailed records began.
or even the Global Sea Ice area
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.ice.area.withtrend.jpg
Which shows a similar drop below the average.
All this melt last year in a year of Solar reduction
http://www.solarcycle24.com/
But come on now guys, it’s cooling right??????
Chris, you sound much too like Kim from Dot Earth to be taken seriously. Every conversation starts and ends the same way.
“You are wrong, see my analysis”
“[snipped reams of evidence to the contrary], you should educate yourself”
“You are wrong because I think you are”
End of rational debate or conversation.
Julius, I didn’t mean to snark at you; you’ll find from the other comments and pointers that it’s not just arguing about angels on pinheads.
Chris, well said above:
> serious amounts of study to do.
> Need to take a longer break
People’s replies to earlier posts will likely keep rolling in; you deserve time off to read and think, I hope you won’t be tempted to answer everything, it’ll simmer down as people realize you’re taking time to study.
Enjoy the conjunction; don’t miss that, everyone. I hope you have clear sky for the view tonight. And don’t miss seeing the ISS when you have the chance, it’s a lovely sight too when it passes overhead shortly after sunset.
The full title of this piece is “Summary for Policymakers of the Report of the Nongovernmental International Panel on Climate Change”
Oddly enough there doesn’t seem to exist any report to which this is a summary.
David Steven at #91: There is an exercise being conducted to “update” the AR4 picture prior to next year’s Copenhagen COP meeting in December. It’s being organised by the University of Copenhagen at the behest of the Danish government, and is scheduled for 10-12 March next year. There’s more about the background to the meeting in this interview at Scientific American.
Hopefully not inspired in any astrological sense, though I’ve got to wonder …
Gareth at #111 – thanks so much for the info.
The denialist list is a useful reference point. Do your contributors, I wonder, ever read any of this material? This, for example, from G and T (Physics professors):
Global climatologists claim that the Earth’s natural greenhouse effect keeps the Earth 33 C warmer than it would be without the trace gases in the atmosphere. 80 percent of this warming is attributed to water vapor and 20 percent to the 0.03 volume percent CO2. If such an extreme effect existed, it would show up even in a laboratory experiment involving concentrated CO2 as a heat conductivity anomaly. It would manifest itself as a new kind of `super insulation’ violating the conventional heat conduction equation. However, for CO2 such anomalous heat transport properties never have been observed.
They could have gone further. Angstroms experiment, specifically designed to look for this effect, failed to find it.
The combination of the lapse rate (gravity) and thermal conductivity (sensible heat transfer) would generate a substantial temperature differential above the “bare rock” case in an ideal gas or N2/02 atmosphere. Anyone can demonstrate this for themselves by driving up a hill (lapse rate) and putting on a coat on a cold day (thermal conductivity).
How much additional temperature difference does the trace gas radiatiation absorption effect produce? Not much, mainly from the water vapour, and limited to the first few hundred ppm before saturation is reached (Angstrom, again).
In conventional greenhouse experiments (RG Woods) glass absorbs infra-red radiation and rock salt does not. There is no measurable difference in the interior temperatures.
So, G and T would not expect surface temperatures to increase as the CO2 concentration in the atmosphere rises. In so far as these temperatures can be measured sufficiently accurately, they are currently falling.
With 50% of US and 75% of Chinese power generated from coal-fired stations the next 5 to 10 years will be interesting for AGW proponents. (The next 14 months will be interesting for Tamino’s prediction of a 0.5 degree C uptick in the Central England Temperature record this decade).
[Response: Do at least try to say something sensible. ‘G&T’ is complete garbage. – gavin]
–#114:
Fred, you are still hopelessly confused. It’s nice to know that some things don’t change.
(Though, since you bring up the Angstrom experiments, I’ll add that there is a lot of info available on them, here and also particularly at Spencer Weart’s site. Just in case you’d like to catch up a bit.)
G&T are completely are clueless as to how the greenhouse effect works. Their paper represents onw of the most pathetic misunderstandings around–notice that it still hasn’t found a publication willing to take it. To call them physicists is to insult physics.
Re: #114 (Fred Staples)
[edit]
I never made any such prediction, nor would I, because I have time and time again tried to educate people that the noise level of temperature data makes trends on such short time scales extremely uncertain.
You just made this up, and have repeated it numerous times in numerous places, because it’s a convenient “straw man” you can invent in an attempt to embarrass me. You’re just an outright liar.
Here’s what I actually said in my post on Central England Temperature:
There’s no way for an honest person to interpret this as a “prediction of a 0.5 degree C uptick in the Central England Temperature record this decade.”
You’re the one who (in comments to that post) tried to use far-too-short time spans to characterize the trend in CET:
If we use the last 10 years of CET data (which is cherry-picking, starting with the 1998 el Nino year), the trend rate is only 0.05 deg.C/decade plus or minus 0.9 deg.C/decade.
It’s bad enough that you want to ignore proper statistics and gigantic error ranges to make ludicrous claims. But your continued lies about what I did or didn’t “predict” are slanderous.
You owe me an apology. You should also apologize to every reader here.
[Response: Seconded. (and sorry for not catching that in moderation). – gavin]
Tamino, I can think of a scenario in which Fred might not owe you an explanation–and that is if he truly doesn not understand the difference between a trend and a prediction. In this case, we all owe Fred a great deal of pity.
On another subject: So, Fred, interested in playing po–ker,some time?
Fred #114
http://www.tyndall.ac.uk/general/history/JTyndall_biog_doc.pdf
…and it’s called radiative transport, not conduction.
This happened in 1859. Try to keep up with the literature ;-)
Hi everyone
I am new to this site so please help me out. There are a few thing I cant seem to grasp in the climate debate. But then again I am no rocket scientist (still a scientist though).
I know that the following things cannot possibly be challenged.
1) There exists no historical data that suggest that CO2 drives the climate. On the contrary data suggest (not prove though) that temp drives CO2
2) We are concerned with the warming that has occurred in the last century. However more than 50% of this warming occurred before 1940. At this time the anthropogenic sources of CO2 cannot possibly have been large enough to change climate.
So what are we left with??
Please help me out
[Response: On the off chance you are serious and not just playing the faux naif, you completely miss the real issues. First, CO2 is a greenhouse gas as has been measured in laboratories and in the atmosphere for over a century. And second, we aren’t particularly concerned with the warming so far – that is just for testing that we know what we are doing. The worry is what it means for the future…. – gavin]
Dear Gavin
Tank you for your response. I am not playing. I am dead serious. I am aware that CO2 has been measured in the atmosphere, and also that CO2 is a greenhouse gas. That is trivial knowledge. But do we have any data that suggest that CO2 drives climate?? I know that CO2 and temp are somewhat correlated, but that is not enough..is it??
If CO2 has not driven climate in the past, then how can we imagine to change the future climate changes by limiting CO2 emission.
I do not write on this site to play pranks. I try to get a fair discussion going and maybe learn a thing or two in the process….
[Response: These are all very basic strawman questions and answers have appeared on this site and elsewhere many, many times. But just to clear, yes, there is evidence that changes in CO2 and other GHGs have driven climate change in the past (the PETM is the biggest, the temperatures at the LGM can’t be explained without a significant role for CO2, the long term cooling over the Cenozoic appears to be related to decreasing CO2, basic radiative physics, detection and attribution over the 20th Century etc.). Your second question, pre-assumes a negative response to the first and is therefore moot. If you want to have a fair discussion, read up on some background first (‘Start Here’ button at the top of the page). – gavin]
Re: #120 (Christian Holm)
What is your source for the claim “However more than 50% of this warming occurred before 1940.”?
Christian #121.
Uh, YES. There is data that suggests CO2 drives climate. CO2 is a greenhouse gas as you admit. And what is the only energy source for weather (and so therefore, in the long term, climate)?
The Energy From The Sun.
So if we hold on to that energy, the effect the Sun’s Energy has on the climate and weather will be driven with a different energetic forcing.
The data is therefore: CO2 is a greenhouse gas.
PS Christian.
Do we have any data from the mesozoic era about deaths of animals by automobile collision? No??? So how do we know that cars cause deaths????
That is the strawman being alluded to in your response. The dinosaurs didn’t burn oil. Therefore this current gargantuan burning of fossil fuels is unprecedented. Expecting data to show that in previous times the unprecedented actions did the same thing as it is being attributed to doing now is a ridiculous query: if it had happened before, it would not be unprecedented.
@122 (tamino)
That claim has been made by Baliunas at the Marshall Institute [wwwDOTmarshallDOTorg/article.php?id=79], the Hoover Institution [wwwDOThooverDOTorg/publications/digest/3532016.html], Steve Milloy at Fox News [wwwDOTfoxnewsDOTcom/story/0,2933,93466,00.html], the WSJ Editorial pages [wwwDOTopinionjournalDOTcom/columnists/pdupont/?id=110009693], etc.
You know, reputable sources for scientific information.
(ReCaptcha: heat dealings)
Christian Holm,
You need to read this page or this one which addresses common skeptical arguments– the ones you bring up are many years old and have been addressed many years ago. The usage of them has gradually faded in more academic forums, so take that into account when people show little patience for addressing them in detail.
Re Christian @120: “1) “There exists no historical data that suggest that CO2 drives the climate. On the contrary data suggest (not prove though) that temp drives CO2”
You’ve already been set straight on your questioning of CO2 as an historical climate driver, but you will find it helpful if you grasp that CO2 can be both a feedback and a forcing, or driver as you put it, depending on the circumstances, and that in either case it will add warming.
When CO2 lags temperature, such as at the end of the last ice age, it is clearly not the initial forcing, or driver. That was increased solar insolation due to Earth’s orbital and rotational geometry (Milankovic cycles). As the surface, ocean and atmosphere warmed more CO2 then entered the atmosphere, where it added still more warming. Thus it was a positive feedback in that situation, reinforcing the initial forcing.
Today, absent any initial increase in solar insolation or other direct energy input, but with a measured, continuing, and accelerating increase in CO2 from the burning of fossil carbon fuels, CO2 is acting as the direct initial forcing.
It really should not be hard to grasp, especially for a scientist, although as we’ve seen so often, that’s no guarantee.
Captcha predicts: ft snowdrifts
#127–
Very well put, Jim.
I would only add that this point is the one thing I regret about “An Inconvenient Truth.” The correlation between CO2 and temperature was stressed so strongly that the distinction you draw so clearly (and Mark so colorfully above!)was rather lost, to the confusion of many.
CO2: feedback then, forcing now.
Thanks, Kevin, but there are a few other regrettable moments in AIT, including illustrating, quite accurately, mind you, the consequence of the melting of the Greenland and West Antarctic ice caps and subsequent sea level rise but without providing some kind of realistic time scale range, or the outright gaffe that we’re already seeing climate refugees emigrating from Tuvalu, although discussions to that end are indeed ongoing. Still, Gore got far more right than he got mixed up or wrong.
Captcha provides an alternate to “deniers”: Blockheads
Any number of things, but the first is that you don’t win with the denialists by showing how wrong they are, you only win by showing how incoherent and silly they are. The hallmark of the NPCC report is that every paragraph blows away the paragraph before.
Dear all
Thank you very much for your patience. I will read up on the articles and study the contents of the homepages that you have generously linked to.
I have just a few comments to Mark.
1) In #123 I wrote “I am aware that CO2 has been measured in the atmosphere, and also that CO2 is a greenhouse gas”. So why do you try to convince me that CO2 is a greenhouse gas???
2) Your arguments using dinosaurs are not logical. You are right that anthropogenic emissions of CO2 are unprecedented. But there are plenty of phenomenons that could (and might have) emitted at least the same amounts of CO2 into the atmosphere in the past (Volcanos etc..). So we dont know if this rise in CO2 is unprecedented.
3) Your “car accident” example is so below anything I have ever heard I think it qualifies to ban you from this site.
Later
Later
I look forward to the update from ISC on climate change (111) although it mentions May 2009 on the web site. Thats the best news I’ve heard in some time.
We realy should have an update once a year given the current urgency of the subject. I fear we are playing a catch up game here and will be changing our targets into the coming decades as more info becomes available.
reCapture is quite appropriate for this strings topic: “long forgery”
Re: #122 Tamino Re: #120 (Christian Holm)
“What is your source for the claim “However more than 50% of this warming occurred before 1940.”?
Christian did not reply but his claim would be substantially correct if he replaced “more than 50%” by “about 50%”.
Using the HadCRUTv3 data set with 60-month central moving average the main trends were:
– 1911 to 1942; a rise of 0.59 C at a rate of 0.02 C/y.
– 1942 to 1980; fluctuating temperatures with an overall fall of 0.13 C
– 1980 to 2004; a rise of 0.59 C at a rate of 0.025 C /y.
Different smoothing, interpretation and data bases would give slightly different answers. For example, it could argued that rising temperatures started in 1948. In this case the late 20th century warming was 0.69 C, higher than the early century warming, but at the slower rate of 0.013 C/y.
I am back. It is daytime here….thus the delay in replies
The links were very helpful. This is what I got from reading them:
It seems that although solar activity has driven climate in the past, this might not be true for the last three decades.
Yes lab work has shown that CO2 is a greenhouse gas and that it contributes to keeping the globe warm (we can only calculate and speculate on how much, not measure this).
Although there might (not consensus all the way around) not be cooling of the earth in the last decade, it does seem like the heating has slowed down, in spite of CO2 continueing to rise.
Together, I think that the basic premise, that anthropogenic CO2 is the primary driver of recent climate warming (later than 1975, since there is agreement that solar activity drove climate), is still based only on three things. Speculations, assumptions and computations.
Christian Holm, You forgot one very important leg to the stool: evidence. No other mechanism simultaneously explains both tropospheric warming AND stratospheric cooling. No other mechanism explains as conveniently the pattern of warming–the degree of polar amplification, the warmer overnight lows, later first frosts, earlier thaws. Add to this the fact that no other forcer is currently increasing in intensity. The evidence is quite cogent. Keep reading.
#134 Christian
First, if there were no greenhouse gases, the earths temperature would
follow the Stefan–Boltzmann law for black body radiation.
This works out to around 0F or about 55F cooler than what it is.
It’s simple physics. Not much speculation.
Second, the National Climate Data Center maintains a record of
global temperatures. By their records, the warmest year was 2005.
The warmest 3 year average is the last 3 years.
2007 probably would have been the warmest year on record, but for
La Nina conditions that started in Sept 2007.
http://www.ncdc.noaa.gov/oa/climate/research/anomalies/anomalies.html
There has been a lot of work to determine how much of the recent warming
is from Natural vs Human causes and the probability that it is
natural or radom is very slight. On the other hand, I suspect you will
find that there are significant political and economic concerns that
would rather not accept such a conclusion.
There is science and there is opinion.
Not everybody can tell the differance!
Christian’s position seems similar to that of other scientifically literate sceptics that I meet. Unlike many deniers: they do not dispute the evidence of the temperature record; they accept that the increase in CO2 is anthropogenic; they accept that CO2 is a greenhouse gas; they accept that while solar forcing plus CO2 and other amplification might have been the primary mechanism in the past it is possible for CO2 to be a forcing mechanism in the future. But, they also realise, as does Christian, that the early and late 20th century warming periods were similar in duration and magnitude and were separated by a cooling period. Until there is a unified theory that explains both of the warming periods and the cooling period they will also remain sceptical.
[Response: The ‘unified theory’ is what goes into the models. All of the forcings need to be included and you want the natural variability needs to be realistic. As you can tell from fig 9.5 in IPCC AR4, the long term 20th C trends are well captured, and the 1940’s excursion is well within the spread of the models internal variability. So what needs to be explained? It is not the long term trend (driven in part by ghgs, but also trends in solar+volcanic), but really just the excursions around it. The 1940s are clearly a positive excursion over the expected (forced) trend. But it is possible that the forcings used in AR4 are incomplete or wrong – in which case the 1940’s might be part of a forced change (but there is no evidence of that to date), or, as I would judge more likely, the 1940s were an expression of internal variability – possibly related to the ocean overturning. But this idea that everything pre-1940 can’t be explained is bogus. – gavin]
Christian, #131
1) You must have a very weak personality if you found that so objectionable you would ban me.
2) You don’t have the power to ban me.
3) What more do you need than “CO2 will trap heat”? Do you have ANYTHING that would make that ineffective in the atmosphere? If not, why do you need data other than the data showing that CO2 is a greenhouse gas?
Christian
> we dont know if this rise in CO2 is unprecedented.
Rate of change is what makes the airborne fraction increase — a rate of increase in CO2 faster than natural biogeochemical cycling can remove it.
E.g.:
http://scholar.google.com/scholar?sourceid=Mozilla-search&q=%22Deccan+traps%22+%2Bco2
#131 claims that “You are right that anthropogenic emissions of CO2 are unprecedented. But there are plenty of phenomenons that could (and might have) emitted at least the same amounts of CO2 into the atmosphere in the past (Volcanos etc..). So we dont know if this rise in CO2 is unprecedented.”
Is somewhere between an argument from personal ignorance, a troll and a red herring. The short answer is that we have a reasonable idea of what CO2 concentrations have been over the past half million years from ice cores, and 380 ppm is about 100 ppm higher than it has been. If you go back a few million years, proxies say that this is still the case, it is only tens to hundreds of millions years ago that the CO2 concentration was much higher, and of course, a couple of billion years ago we had a nitrogen CO2 atmosphere, but that was then on a very different planet.
These changes did not happen over a century either. What is shocking about the current situation is that it has happened so quickly. Moreover there is excellent evidence that it is the result of fossil fuel combustion.
So we now get to look at Chris’ magesterial wave of the hand as he pulls out the bunny. Sorry Chris, you have to show some evidence for your claims before they are taken seriously.
Re #137: Prior to about 1950, natural changes dominated the climate.
It has only been since that time that man made changes have become
dominate. It’s not that man made changes were not a factor prior to
that time or that natural processes no longer influence the climate.
Rather, it just that since about 1950 human activities have overcome
natural changes.
For example, total solar irradiance is currently at it’s lowest level
in over 50 years, and yet we are looking at the warmest 3 year period since
the instrumented record began. Furthermore, we are likely to establish
a new yearly record average temperture as soon as ENSO returns to a
positive phase. In fact, we could even establish a new record with
neutral ENSO conditions as was the case in 2005.
Lastly, the cooling of the 1970’s that some are so fond of pointing
out is only in relation to the 1940’s. The 70’s were actually warmer
than every other previous decade and every decade since the 1950’s has
been progressively warmer. The 80’s and 90’s were both warmer than
the 40’s and the current decade is on track to be the warmest yet.
There was a lot of solar activity in the late 30’s and early 40’s, which
can explain why that decade was so warm, but current solar activity is
down from those levels and yet we are still witnessing warming. Also, the
warming that we are seeing isn’t from elevated daytime highs as much as it is
from elevated night time lows. So, clearly something is going on with
the insulation properties of the atmosphere and since it’s mostly in the arctic
we know that it’s not urban heat islands.
Why anyone would seriously argue with Eli about his knowledge on climate is beyond me.
‘No grasshopper! The greenhouse gases are ‘gases’. They heat the atmosphere and surface and a warmer atmosphere transfers some of that heat to the ocean below. You still have much to learn.’
Hrmm.. a little ironic that this cheeky answer is also wrong… I mean, greenhouse gasses aren’t a heat source – they just capture and store heat from other sources – namely the sun.
Not that that detracts anything from the validity of the response.
A minor aside: You call the global cooling of the 70s thing the “granddaddy of all contrarian talking points”. I use it myself occasionally to support my skeptical position, but it is decidedly 2nd or even 3rd tier and not particularly important. Is “granddaddy” kinda tongue-in-cheek or do many of my fellow skeptics actually rely heavily on it?
#140 -Eli
Please explain to me why the laws of physics change as you go back in time. And why our globe was a different planet then.
naught101, #143.
When a gas is hot, it is a heat source.
How else can the heat get out?
#134 Christian Holm:
It seems that although solar activity has driven climate in the past, this might not be true for the last three decades.
Why do you use the word ‘might’? This indicates you think it is very likely that the sun has in fact been responsible for the increasing temperatures over the past decades. You are the one basing your conviction on speculation here because there is no plausible evidence to support this assertion. Based on the available evidence, you should have said: “It seems that although solar activity has driven climate in the past, this is very likely not true for the last three decades”
We can not measure the warming effect of CO2 in the way you would like to see it: as an experiment conducted on various clones of the Earth. Believe me, every scientist would like to be able to do that. But we can’t. We are therefore forced to use the second best option: calculations (climate models). That doesn’t mean this second best option can’t produce useful results. Not 100% certain. Not 100% accurate. But: useful, good enough.
Yes lab work has shown that CO2 is a greenhouse gas and that it contributes to keeping the globe warm (we can only calculate and speculate on how much, not measure this).
The scientific word for ‘speculation’ is ‘uncertainty’. The uncertainty in the calculation of the warming effect of CO2 has been determined. Guessing from your posts, you seem to think that science has to be 100% complete and accurate to be ‘right’. Science is never 100% complete and accurate. Never was, never will be. The correct question regarding AGW is not: “Do we know for certain that CO2 is causing climate change and do we know exactly how much?” The correct question is: “is the uncertainty small enough to warrant action?”
Although there might (not consensus all the way around) not be cooling of the earth in the last decade, it does seem like the heating has slowed down, in spite of CO2 continueing to rise.
The power of positive thinking helps you to be successful in life. It has however no effect on the climate.
#87 Barton Paul Levisencaptdallas — I’ve been using the Lean 2000 results as more or less canonical, which I know is always a careless thing to do in science. I even have a web page listing the whole table. I think Wang and Lean published a revised table in 2004; do you know if there’s a later one? If not I really ought to replace my web page with the 2004 data.
Wang 2005, Foster 2004, Svalgaard 2007, There are a few more. It is frustrating to me that so many use Lean 2000 to prove points when there are more current reconstructions.
#142–jcb, they have to be able to recognize “knowledge” reliably first, in order to be intimidated by it. There has been a concerted attack upon this capability going on for some time–see today’s posts on the NIPCC thread. (Where, inexplicably, no-one had yet mentioned Gore’s “Assault On Reason,” which is also much to the point.)
Gavin’s reply to my #137.
I think you are referring to figure 9.5 in Chapter 9 “Understanding and Attributing Climate Change” (the file ar4-wg1-chapter9.pdf ). If you are, it does not really confirm your statement that the idea “that everything pre-1940 can’t be explained is bogus”.
The 20th century had two similar 30 year periods with generally increasing temperatures with a flattish but cooling 30 year period between. In the graph as presented the observed record had an increase of 0.75 C for the first period, a fall of -.45 C for the second and an increase of 0.8 C for the third. The modelled sequence has 0.3 C for the first period, -0.2 C for the second and 0.75 C for the third. In other words the early century warming and the mid-century cooling are both underestimated by a factor of more than 2.
During mid-century cooling the model shows a generally rising trend and only falls following the Mount Agung volcanic eruption – with a VEI of 5. The chart shows two much larger VEI 6 eruptions (Pinatubo and Santa Maria) which were included but another VEI 6 eruption, Novarupta in 1912, appears to have been ignored. Two other VEI 5 eruptions (Cerra Hudson in 1991 and St Helens in 1980) do not appear. I have not yet had time to read the supplementary appendix and it may be that the reasons for including some eruptions and not others are covered there.
[Response: VEI is not a sufficient index for the importance of a volcano to climate. You need two other things – first, it helps a lot if it is a tropical volcano, and second, there has to be significant SO2/sulphate injection into the stratosphere. The first is necessary in order to get a global distribution of aerosols, and the second is necessary to ensure a significantly long lifetime of the those aerosols. SO2 in the lower atmosphere rains out very quickly (weeks) compared to years for stratospheric aerosols. Mt. St. Helens for example, fits none of these criteria. Look up Sato et al, 1993 for a discussion of the forcing dataset construction. – gavin]