THIS PAGE HAS BEEN ACTIVATED AS THE NEW STATESMAN BLOG IS NOW CLOSED FOR COMMENTS
At 10am this morning, the New Statesman finally closed the Mark Lynas thread on their website after 1715 comments had been added over a period of five months. I don’t know whether this constitutes any kind of a record, but gratitude is certainly due to the editor of of the New Statesman for hosting the discussion so patiently and also for publishing articles from Dr David Whitehouse and Mark Lynas that have created so much interest.
This page is now live, and anyone who would like to continue the discussion here is welcome to do so. I have copied the most recent contributions at the New Statesman as the first comment for the sake of convenience. If you want to refer back to either of the original threads, then you can find them here:
Dr David Whitehouse’s article can be found here with all 1289 comments.
Mark Lynas’ attempted refutation can be found here with 1715 comments.
Welcome to Harmless Sky, and happy blogging.
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10,000 Responses to “Continuation of the New Statesman Whitehouse/Lynas blogs.”
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Max & Pete,
Concerning your extended and merry exchanges above, and the semantics of various things, I would like to highlight that my recollection is that Max long ago described that the so-called T-plateau and cooling commenced in 1998. (As have many others, and me). I think Pete then objected to this on his grounds that the 97/98 el Nino was so unusual, that it was unfair to use the resultant 1998 T. (Although of course, for example, it was OK for the IPCC to use the 1998 T instead of the much lower 2000 T, when it suited them in their TAR 2001!)
Then Max, (a tender Swiss guy), obligingly agreed; something like; OK, if you (Pete) don’t want to take it from 1998, let’s discuss it from a start-point of 2001. Let me emphasize; from 2001, not 2000 or 1999 or any other arbitrary choice. Unfortunately, this places it all into a marginally tenuous short time series, and I will describe later some of the difficulties involved in that.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(1)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Before that; let us discuss whether there is any logic in either excluding 1998, OR starting at 2000, as recently launched by Pete.
At first sight, it may seem remarkable that 1998 was such a hot up-spike. However, it is also first-sight remarkable that both 1999 and 2000 were sharp reversals, almost like a “correction” on the Stock-Market. SO, this raises a question; Is such “correction” unusual, and the answer is NO! Go back through the records, and it is statistically significant that whenever there was a sharp up-spike, it is typically followed by a sharp reversal of a year or few, generally proportional to the scale of the event.
Pete, has stated a time or two before that there IS a thermal response-time in the weather system, depending on the event. This is clearly true, for instance you can see in the NOAA data (find link above) that most of the so-called 1998 El Nino warming actually occurred in 1997 at sea-level, yet the published global response was in 1998. Yet another response is the “correction” to la Nina in 1999 through 2000, and a touch into 2001. Thus, I argue that the data for 1998 through 2000, (and less so, maybe even 1997 through 2001), should not be divided from each other, because they are ALL part of the same event!
The facts are, that ENSO cycles are clearly just one cyclical part of the general warming trend, and there is absolutely no sense in excising any year-dated part of them as has been proposed by some researchers, because no single year-dated T is without some unknown “inertia” either negative or positive, before or after-hand.
Pete, if you now want to start your straight-line trend in 2000, (after accepting 2001 as the original basis for discussion), then you must also allow Max to start at 1998, since 1998 through 2000 are very clearly inseparably RELATED in outcome.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(2)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You guys may have noticed that I have not joined-in on the debate on linear smoothing of noisy short series data. This is largely because, as a coalface guy, I think it is OVERVALUED in the “papered scientific community“, and in my next post, I will demonstrate at least one conundrum in the very area that Max & Pete are arguing.
In brief; the significance of such trends can be greatly altered depending on the start and end points that may be arbitrarily selected. (even by as little as 1 year) Also; do some points have more significance to others, or is a linear trend appropriate….etc.
Meanwhile, take a squiz at my graphic; TICKLED PINK and BLUE; and follow the practice of the IPCC, and draw straight lines wherever you like! It’s great fun!
TICKLED PINK and BLUE
TonyN,
Anyone;
In my 3001 above, I was rather naughty in how I posted my image, (TICKLED PINK and BLUE), following some failures trying to follow the rules as described by TonyN.
I may well have a corruption in my OS, or I’m losing my marbles, who knows!
Nevertheless, the image looks OK this end.
Did anyone have a problem with viewing it on their system?
Just to re-raise the topic of the early 20th century warming we need as always to start with a graph:
Its pretty naive to try to do the sort of calculation that Max tries with CO2 and temperature rise for a small segment of the graph. Either that or he is deliberately engaging in a campaign of disinformation to try to confuse rather than educate.
So, what can we say? For a start there is no such thing as proof but the evidence of the graph is that every 25 ppmv increase in CO2 levels increases the temperature by about 0.2 degC. If CO2 levels double from their preindustrial level of 280ppmv to 560 ppmv or an increase of 180ppmv from where we are now the temperature will rise another 1.4 deg C.
Its already risen by 0.8deg C so this would mean 2.2deg C contibution from extra CO2 in the atmosphere. This is on the lower end of the IPCC range but doesn’t of course take into account any delayed effects. And as JZ will know very well his swimming pool will be cooler at the start of summer than at the end even if the air temperature is the same.
The ocean is like a huge swimming pool so we would expect to see some delay.
Of course CO2 is not the only climate driver. It can’t be responsible for all the peaks and troughs. But the graph does show that the effect of AGW was not negligable in the early 20th warming, as some might have previously suggested, and was responsible for about half of the 1940 increase.
TonyN (or anyone!) my #2992
Although I have XP my mouse commands are quite different to any needed to be able to post a graph.
Could I ask if someone could post the graph on this link so I can easily make reference to it and ask for comments?
http://cadenzapress.co.uk/download/beck_mencken_zurich_uhi.xls
Thanks
TonyB
TonyN: This is not an image, so it will not display as an image.
Let’s see if it works for me
This won’t work. You’ll need to copy the chart. Paste it into Paint. Size it to 15cm max. Save as a *.png file.
Its interesting that CA regard the highly variable CO2 theory as an embarrasment. And so they should. As you’ve said, both the ice cores and Beck can’t be right. If you are rejecting the ice core evidence then you clearly rejecting science too.
Bob_FJ,
You’ve said “if you (Pete) don’t want to take it from 1998 ”
Look I don’t mind when you start it. Take it from 1998 if you like. Use 0.3 degC for 2008 if that is what you think it will turn out to be for this year. Who cares if the century starts in 2000 or 2001. It makes f… all difference to what will happen later in the century.
Re: 3006, Peter
CA did not consider Beck’s research to be an ’embarrassment’.
Steve McIntyre is a mathematician, not a physicist, and he tries to keep his blog focused on subjects in which he has some interest and expertise. The problem with the Beck research was that it created so much interest that discussion of Co2 threatened to swamp everything else. It was transferred to the CA message board.
TonyB,
I can’t help you with your operating system, but what you describe sounds like a settings problem and not corruption. When XP was launched I seem to remember that you could set it to use an interface that was similar to Windows ’98 so that people could make the transition more easily. This may explain why you get a different drop down menu when you right click. But your main problem is that you need to re-size large images to about 600 px wide so that they will fit the comments collumn, as Peter said.
Peter 3006
I reject easy assumptions- not science.
I reject the idea that hundreds of our brilliant forefathers are ALL wrong
I reject the notion that the highly complex science involved in gaining ice core readings is completely foolproof.
I also reject the idea that our absurdly small input into the overall co2 inventory has anything like the dire effects stated.
TonyB
Hi Peter,
Your curve (3003) is beautiful. It does fail to highlight the multi-decadal warming and cooling cycles we have hexperienced over the total time period that Hadley global measurements exist. But let me paraphrase your message, “Its pretty naïve to try to do the sort of calculation that Peter tries with CO2 and temperature rise while ignoring everything else.”
But I agree that a long-term look makes more sense than just concentrating on the late 20th century warming cycle as IPCC has done ad nauseam in its 1,000-page AR4 report.
Your curve “naïvely” shows only two variables: atmospheric CO2 concentration and global temperature. It “naïvely” ignores ENSO cycles (please refer to the curve posted by Bob_FJ, which shows how these relate much more closely to temperature than CO2). It “naïvely” ignores the solar impact of unusually high 20th century solar activity, as reported by numerous solar scientists. It “naïvely” ignores volcanic activity.
So the “evidence of the graph” is just not there, Peter. It’s much too simplistic and “naïve”.
Now to your figures. From 1850 to 2008 the Hadley record shows a total linear warming of around 0.65C (see attached curve).
http://farm4.static.flickr.com/3229/3079820242_1f35e5196f_b.jpg
Solar scientists tell us that the unusually high level of 20th century solar activity resulted in a global warming of 0.2C to 0.5C, with a mean value of around 0.35C. The links to several of these studies can be found on p.1 of this site (posts #87 to 97).
If we “naïvely” ignore for now the higher level of El Niño activity during the latter 20th century (remember the graph from Bob_FJ) and assume (as IPCC does) that other anthropogenic effects cancel each other out, we have around 0.3C warming from increased CO2 concentrations, all other things being equal (which, of course, they are not, except in the “naïve” virtual computer-generated AGW world).
So let’s do a “sanity check” on your estimated 1.4C warming from today until year 2100.
1850 CO2 concentration = 285 ppmv (C1)
2008 CO2 concentration = 386 ppmv (C2)
C2 / C1 = 1.354
ln (C2 / C1) = 0.3033
dT total = 0.65C
dT solar = 0.35C
dt CO2 = 0.30C
Let’s assume that CO2 will be at twice its 1850 level by year 2100
1850 CO2 concentration = 285 ppmv (C1)
2100 CO2 concentration = 570 ppmv (C2)
C2 / C1 = 2
ln (C2 / C1) = 0.6931
dT from added CO2 (1850-2100) = 0.3 * 0.6931 / 0.3033 = 0.69C, say 0.7C
dT from added CO2 (1850-2008) = 0.3C
So the added warming from CO2 we can expect from today until year 2100 is 0.7 – 0.3 = 0.4C.
Looks like your 1.4C figure is exaggerated by a factor of 3.5 and does not pass the “sanity test” based on the actual observations to date, Peter.
But it was a good try, anyway (and a beautiful curve).
Regards,
Max
Hi Peter,
You wrote to TonyB: “If you are rejecting the ice core evidence then you clearly rejecting science too.”
“Rejecting science”?
Many people have pointed out the pitfalls of relying too heavily on ice core evidence.
Actual in situ analytical measurements of trace gases such as CO2 at the time are just as much “science” as ice core reconstructions hundreds of years later.
To say that one is “rejecting science” when one rejects ice core evidence in favor of actual analytical measurements at the time is plain silly, so I am sure that is not what you really wanted to say.
Am I right?
Regards,
Max
Hi TonyB,
Reur dilemma on posting graphs.
I took your Excel graph (not including the data tabulation), copied it into Powerpoint and converted it first to a pdf file and then a jpg file, which could then be uploaded as a “picture” with Flickr.
The process is cumbersome, and as you can see the fonts seem to get changed in the process.
http://farm4.static.flickr.com/3208/3080273274_65c109fcb3_b.jpg
http://farm4.static.flickr.com/3208/3080273274_65c109fcb3.jpg
Now I’ll try pasting them on the blogsite. Let’s see if it works.
(Peter may have a better way of doing this.)
Regards,
Max
Hi Tony,
Looks like it worked, but a part of the text on the right side got truncated in the process.
The larger picture is easier to read than the small one.
I tried doing the same with your entire file, but it did not work (half of the file got chopped off in the process).
Regards,
Max
Hi Peter,
I know it’s an oversimplification (since we ignored ENSO, PDO, NAO, volcanoes, etc.), but the nice part about the calculation in 3010 is that it checks fairly well with the IPCC estimate of radiative forcing from CO2 (Myhre et al.), excluding any imaginary “positive feedbacks”, of course.
The principal positive feedbacks” programmed into the IPCC models are from clouds and water vapor. Physical observations have shown that the IPCC assumptions on these are false:
· Clouds result in a strong net negative feedback with warming as confirmed by actual physical observations (Spencer et al.), rather than a strong positive feedback as assumed in the climate models
· Water vapor feed back with warming is positive but much lower than assumed in the climate models, as confirmed by actual physical observations (Minschwaner and Dessler)
Together these two corrections to the IPCC model assumptions result in a negligible net impact from feedbacks and we are back to the IPCC 2xCO2 climate sensitivity of 0.7C, in accordance with the greenhouse theory.
To walk you through this, IPCC tells us that the radiative forcing from the CO2 increase from pre-industrial year 1750 (280 ppmv) to 2005 (379 ppmv) was 1.66 W/m^2.
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
[Note that calculating this using the 5.35 factor from Myhre et al. gives a very slightly lower figure = 5.35 * ln (379 / 280) = 1.62 W/m^2.]
http://www.grida.no/climate/ipcc_tar/wg1/222.htm
The period 1850-2008 has only a slightly lower ln (C2 / C1) than the period cited by IPCC, so let’s stick with the IPCC estimate of radiative forcing (dE) of 1.66 W/m^2.
Using the derivative of Stefan-Boltzmann
dT / dE = 1 / 4 * [sigma] * T^3
where sigma is 5.6705E-08 W/m^2 * T^4
and T = 15C +273.16 = 288.16K
dT = 1.66 / 4 * 5.6705E-08 * (288.16^3) = 1.66 / 5.427 = 0.31K = 0.31C
The theoretical greenhouse warming from CO2 from 1850 to 2008 equals 0.3C.
The estimated warming from increased solar activity equals 0.35C.
So it looks like the physically observed 158-year linear temperature increase of 0.65C can be well explained by two factors alone (if we believe IPCC on CO2 radiative forcing and the numerous solar scientists on solar forcing).
Of course, it could be that there was no warming from CO2 at all and that the observed warming came from the solar effect plus some other factor (ENSO?).
But, at any rate, you don’t have to worry about a 1.4C temperature rise from added CO2 by year 2100; the more likely theoretical warming is around 0.4C.
But, then again, it all depends on what the sun (our planet’s only source of energy, as we all know) will do over the next few decades.
Regards,
Max
I don’t know why I’m doing this but here is Tonyb’s graph.
Its too wide too fit comfortably in this page and the lettering too small to be scaled down, but the link is here:
http://farm4.static.flickr.com/3002/3080943112_abfaafb89f_o.png
On second thoughts it may not be too bad
This is an interesting perspective on our AGW debate.
There has been much made by the AGwer`s of the recent Arctic sea ice extent but little lip service regarding the temperatures in Greenland over the last 100 years.
A study in 2006 by Petr Chylek, M. K. Dubey and G. Lesins called :
Greenland warming of 1920-1930 and 1995-2005.
There are significant differences between the global temperature and the Greenland temperature records within the 1881-2005 period. While all the decadal averages of the post-1955 global temperature are higher (warmer climate) than the pre-1955 average, almost all post-1955 temperature averages at Greenland stations are lower (colder climate) than the pre-1955 temperature average.
To summarize, we find no direct evidence to support the claims that the Greenland ice sheet is melting due to increased temperature caused by increased atmospheric concentration of carbon dioxide. The rate of warming from 1995 to 2005 was in fact lower than the warming that occurred from 1920 to 1930.
http://meteo.lcd.lu/globalwarming/Chylek/greenland_warming.html
The Viking farm under the sand in Greenland.
Claus Andreasen of Greenland University could not have guessed what would be revealed when they excavated the ruins of the five-room, stone-and-turf house in the early 1990s. As the archaeologists dug through the permafrost and removed the windblown glacial sand that filled the rooms, they found fragments of looms and cloth.
The points being made are that there is NO correlation between the modern Greenland warming and CO2.
There is historical not proxy evidence that clearly shows the medieval warm period was warmer than today. The stone farmhouse could not possibly have been built under the permafrost, therefore the present warming is not unprecedented within the 1000 year period which shows the hockey stick to be the result of GIGO.
Rob, Reur 3018:
You’ve reminded me that I should finish a graphic I started some weeks ago, (prompted by Brute in his 2555), for a discussion on how sea-ice cover may have been assessed BEFORE the availability of even the early most basic broad-view satellite observations and whatnot!
The facts are, that Arctic sea-ice is a very dynamic thing; for instance, that recent intrepid English explorer, (Haddock?), found himself marooned on an ice-island, and placed a whole rescue team of others in risk, (and at significant financial cost), in order for him to be rescued. No matter; he has since been REWARDED with big funding to do some more stuff up there, although I’m puzzled as for what end-purpose. (seems a VERY daft waste of money to me!)
And, then as just ONE other thing; NASA; JPL; published in October 2007:
EXTRACT: Nghiem [team leader] said the rapid decline in winter perennial ice the past two years was caused by unusual winds. “Unusual atmospheric conditions set up wind patterns that compressed the sea ice, loaded it into the Transpolar Drift Stream and then sped its flow out of the Arctic,” he said. When that sea ice reached lower latitudes, it rapidly melted in the warmer waters.
http://www.nasa.gov/vision/earth/lookingatearth/quikscat-20071001.html
Of course there has been much naïve commentary by some individuals that in the early 1900’s various marine explorers had difficulty in winding their way through the very complex Canadian archipelago. Well, that is hardly surprising without the recent modern mapping, and various navigation aids, and whatnot!!!
For an early explorer‘s consideration: Shall we go to the left or right of this ‘ere island? And later: ho hum, we have found ice!…. Let’s go back and try another way…. Or stay here for the season!
BTW, naval structural engineering, (ice collision protection), has also improved since those times.
Well anyhow, keeping it brief, here is my graphic, which hopefully might be the basis for some RATIONAL discussion:
3SubsNorthPole
Hi Rob,
Your reference to the Viking farm recovered from the permafrost in Greenland is interesting. It provides another “nail in the coffin” of the deniers of a Medieval Warm Period that was warmer than today (without benefit of man-made CO2).
We have similar evidence of warmer earlier periods here in Switzerland, when receding alpine glaciers reveal signs of earlier vegetation and civilization under the retreating ice.
Of course there are also historical records of medieval alpine silver mines being covered up by advancing ice and snow at the end of the Medieval Warm Period, ancient Viking sea charts revealing coastlines that are now covered by glaciers, old records from China showing that oranges were being grown in regions that are much too cold today, crop records from the Middle East, records of wine grapes being grown in the north of England, etc.
AGW enthusiasts have been generally skeptical of a Medieval Warm Period that was warmer than today, trying to prove otherwise with all sorts of proxy studies (the most notorious of which was the since discredited Mann “hockey stick” using bristlecone pine tree-ring proxies). Others have admitted that there may have been a local warm anomaly in Europe, but that this was by no means a globally warmer period than today.
For me the best proof of a “global” (rather than just a “local European”) Medieval Warm Period are the long-lived Viking settlements in Greenland (which is not very “green” today) and the short-lived ones in Newfoundland, which they named “Vinland” for the wild grapes growing there.
http://www.mnh.si.edu/VIKINGS/1138.html
“According to the sagas, at precisely A.D. 1000, Leif Eriksson, first son of the notorious Erik the Red, voyaged from Greenland for lands sighted to the west. He then landed on the shores of a beautiful place he named Vinland (Vine land). Later voyagers to Vinland met strange peoples, whom they called skraeling.
Ever since these tales became widely known in the 19th century, scholars have debated their veracity while enthusiasts have proclaimed locations from Labrador to Florida as Leif’s Vinland.
But in 1960, undeniable proof of Vikings in North America came to light at L’Anse aux Meadows in Newfoundland, Canada. Several Norse Viking pieces and clear Icelandic- style house foundations gave proof positive that Vikings had indeed landed, and briefly settled, in North America 500 years before Columbus.”
It now looks like the more enlightened “proxy” guys are coming around to the fact of a global MWP. While there have been several earlier studies confirming a warmer global MWP, a more recent study by Craig Loehle concludes, “The mean series shows the Medieval Warm Period (MWP) and Little Ice Age (LIA) quite clearly, with the MWP being approximately 0.3°C warmer than 20th century values at these eighteen sites.”
http://www.ncasi.org/publications/Detail.aspx?id=3025
Steve McIntyre has taken a look at Loehle’s recent (non tree-ring) results, which showed a warmer MWP than today in comparison with those of another earlier (tree-ring) study by Moberg, which showed the current warm period slightly warmer than the MWP.
http://www.climateaudit.org/?p=2403
But IPCC has still not gotten the word. While they have quietly scrapped the discredited Mann hockey-stick, they still refer to contradicting “spaghetti graphs” in order to claim, “Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1,300 years. The last time the polar regions were significantly warmer than present for an extended period [was] 125,000 years ago.”
Tell it to the family who built that 13th century farm that was recently uncovered from the Greenland permafrost.
Regards,
Max
Another study I found, It appears according to this Aug 2008 study that it is the oceans that drive climate.
Abstract
Evidence is presented that the recent worldwide land warming has occurred largely in response to a worldwide warming of the oceans rather than as a direct response to increasing greenhouse gases (GHGs) over land. Atmospheric model simulations of the last half-century with prescribed observed ocean temperature changes, but without prescribed GHG changes, account for most of the land warming. The oceanic influence has occurred through hydrodynamic-radiative teleconnections, primarily by moistening and warming the air over land and increasing the downward longwave radiation at the surface. The oceans may themselves have warmed from a combination of natural and anthropogenic influences.
http://www.cdc.noaa.gov/people/gilbert.p.compo/CompoSardeshmukh2007a.pdf
discussed st :
http://www.realclimate.org/?comments_popup=504
This new report concerns poor management and budgetary practices at the WMO
http://wattsupwiththat.com/2008/12/04/internal-report-says-un-climate-agency-rife-with-bad-practices/
At the top of the report is a link to CA who have many words to say about the so called global measuring of temperatures
The main part of the story is the link to the actual report
Of particular interest to TonyN who has an interest in the UK Met office is this intriguing section;
“Less obvious is the fact that WMO programming is also being used to create the elements of a number of potentially huge and lucrative climate-based financial service industries.
In one hefty promotional document, WMO extols the possibility of new weather insurance products, based on finely-tuned WMO data, that could ease financial credit for developing world farmers and also expand the world weather reinsurance market. Pilot projects for such schemes have been established, the brochure says, in Thailand, Nicaragua and Vietnam, among other locales.
The same document extols “tailored climate information” that can “help enhance exploitation of sustainable natural sources such as wind and solar energy, biomass and hydraulic energy.” It also hails the “development of new financial instruments for hedging weather risk, as well as advances in forecasting (so-called climate derivative products)” which will benefit energy producers and consumers. “It is most important to generate and sustain an effective partnership between the energy sector and the meteorological community,” the document asserts.
Such world-shaping plans are the essence of WMO’s soaring ambitions — and the subject of the vast and sprawling conference at Poznan, which is preparing the way for a new environmental accord that is expected to emerge from a meeting next year in Copenhagen.”
So it looks like the WMO and its constituent organisations are going to actively create the weather data then sell it in all sorts of enterprising manners. This seems a highly commercial move.
TonyB
Peter and Max
Thanks for posting my graph. Perhaps either of you can answer something that has perplexed me since Peter wrote in 3003-referring to his graph;
“So, what can we say? For a start there is no such thing as proof but the evidence of the graph is that every 25 ppmv increase in CO2 levels increases the temperature by about 0.2 degC. If CO2 levels double from their preindustrial level of 280ppmv to 560 ppmv or an increase of 180ppmv from where we are now the temperature will rise another 1.4 deg C.”
When I first posted my graph I said it posed a number of questions- the first was that if co2 was constant at 280ppm yet there were temperature spikes to similar levels to today-did this mean that co2 had no effect?
The second explanation I came up with-that perhaps there were missing co2 peaks and troughs from 240 to 400ppm that would explain the temperature fluctuations-is obviously ridiculous and Ernst Beck is a fantasist.
So as there are no co2 peaks and troughs prior to 1958 the only logical explanations are,…
What?
That the recorded high temperatures prior to todays are a figment of our imagination?
That co2 levels only had an effect on temperature once there was a ’19’ in the year?
That co2 has no dramatic effect on temperature otherwise we could not have had high temperatures in the past at 280ppm?
That the ice cores are wrong (obviously ridiculous)
So Max, I am looking to you or Peter to explain how we can have current temperatures at 380ppm thereby supporting Peters hypothese of 0.2 temp increase equals 25ppm… yet we had similar temperatures to today at only 280-300ppm. How does that work?
Your answers are eagerly sought.
TonyB
Hi TonyB,
I secretly suspected that Peter would do a better job of posting your graph on TonyN’s site than I did, and, sure enough, he did. He is very good at that stuff.
Now to your question about earlier periods of similar temperatures to today with much lower CO2 concentration: I can only surmise, based on the evidence at hand, that there are many other factors out there beside just atmospheric CO2 that affect our climate.
I also suspect, based on paleoclimate data and the laws of physical chemistry, that higher atmospheric CO2 levels are likely to have been caused by lower solubilities at warmer ocean temperatures, rather than the other way around as assumed by IPCC and the AGW crowd.
Solar scientists tell us that a bit more than 50% of the 20th century warming can be explained by increased solar activity (which was at a several thousand year high level in the late 20th century and has now dropped significantly).
Bob_FJ has provided compelling evidence that ENSO oscillations have a strong influence on our climate as well. (Whether these two are in some way related is unknown at this time, but cannot be ignored until we know more about the causes for ENSO (and PDO) oscillations).
It could even be argued that ENSO oscillations are really just “feedbacks” to increased atmospheric CO2 concentrations, but that is even more far-fetched than the current IPCC assumptions on “positive feedbacks” from water vapor or clouds caused by increased CO2, so can probably be rejected.
The jury is still out on the cosmic ray / cloud theory of Svensmark until the CERN CLOUD project results are announced some time in the future.
I do not believe that anyone at IPCC (or anywhere else in the “broad consensus of 2,500 scientists”) has as yet postulated that increased solar activity is a “feedback” resulting from higher atmospheric CO2 concentrations, but who knows what the next suggestion will be?
TonyB, I believe you are following the right course to examine all these interrelationships and skeptically but rationally put into question the currently fashionable AGW explanation for everything that is going on as Peter apparently accepts with his oversimplified temperature / CO2 curve.
As TonyN has said, I hope you will post a “sneak preview” of your abstract on this site.
Lots of luck and best regards,
Max
Max,
You don’t say who these “many people “ are who “have pointed out the pitfalls of relying too heavily on ice core evidence.”
They would no doubt be from the more nutty elements of the denialist blogosphere. M&M obviously don’t want anything to do with them and I doubt that Lindzen and Spencer would want to get too close.