Guest Post by Ira Glickstein.
The graphic from RealClimate asks “How well did Hansen et al (1988) do?” They compare actual temperature measurements through 2012 (GISTEMP and HadCRUT4) with Hansen’s 1988 Scenarios “A”, “B”, and “C”. The answer (see my annotations) is “Are you kidding?”
HANSEN’S SCENARIOS
The three scenarios and their predictions are defined by Hansen 1988 as follows
“Scenario A assumes continued exponential trace gas growth, …” Hansen’s predicted temperature increase, from 1988 to 2012, is 0.9 ⁰C, OVER FOUR TIMES HIGHER than the actual increase of 0.22 ⁰C.
“scenario B assumes a reduced linear growth of trace gases, …” Hansen’s predicted temperature increase, from 1988 to 2012, is 0.75 ⁰C, OVER THREE TIMES HIGHER than the actual increase of 0.22 ⁰C.
“scenario C assumes a rapid curtailment of trace gas emissions such that the net climate forcing ceases to increase after the year 2000.” Hansen’s predicted temperature increase, from 1988 to 2012, is 0.29 ⁰C, ONLY 31% HIGHER than the actual increase of 0.22 ⁰C.
So, only Scenario C, which “assumes a rapid curtailment of trace gas emissions” comes close to the truth.
THERE HAS BEEN NO ACTUAL “CURTAILMENT OF TRACE GAS EMISSIONS”
As everyone knows, the Mauna Loa measurements of atmospheric CO2 proves that there has NOT BEEN ANY CURTAILMENT of trace gas emissions. Indeed, the rapid increase of CO2 continues unabated.
What does RealClimate make of this situation?
“… while this simulation was not perfect, it has shown skill in that it has out-performed any reasonable naive hypothesis that people put forward in 1988 (the most obvious being a forecast of no-change). … The conclusion is the same as in each of the past few years; the models are on the low side of some changes, and on the high side of others, but despite short-term ups and downs, global warming continues much as predicted.”
Move along, folks, nothing to see here, everything is OK, “global warming continues much as predicted.”
CONCLUSIONS
Hansen 1988 is the keystone of the entire CAGW Enterprise, the theory that Anthropogenic (human-caused) Global Warming will lead to a near-term Climate Catastrophe. RealClimate, the leading Warmist website, should be congratulated for publishing a graphic that so clearly debunks CAGW and calls into question all the Climate models put forth by the official Climate Team (the “hockey team”).
Hansen’s 1988 models are based on a Climate Sensitivity (predicted temperature increase given a doubling of CO2) of 4.2 ⁰C. The actual CO2 increase since 1988 is somewhere between Hansen’s Scenario A (“continued exponential trace gas growth”) and Scenario B (“reduced linear growth of trace gases”), so, based on the failure of Scenarios A and B, namely their being high by a factor of three or four, it would be reasonable to assume that Climate Sensitivity is closer to 1 ⁰C than 4 ⁰C.
As for RealClimate’s conclusion that Hansen’s simulation “out-performed any reasonable naive hypothesis that people put forward in 1988 (the most obvious being a forecast of no-change)”, they are WRONG. Even a “naive” prediction of no change would have been closer to the truth (low by 0.22 ⁰C) than Hansen’s Scenarios A (high by +0.68 ⁰C) and B (high by 0.53 ⁰C)!
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davidmhoffer says:
March 20, 2013 at 12:06 pm
…
Troll quality has declined significantly in the last two years. Perhaps this is a proxy for something?
————
See, now that’d be a more worthwhile use of my tax dollars in my opinion. At least it’d be good for laughs. I’d be glad to whomp up some computer models and fiddle with data to
reach whatever conclusion you’d like me toobjectively study the question if we could just resolve the question of where the grant money would come from.During the last century we had two warm “pulses” and one cold, superimposed over a roughly 0.6K rise from the Little Ice Age (which was the second coldest period since we came out of the last Ice Age), each lasting very roughly 30 years. This century, we will have two cold pulses and one warm, leaving us with temperatures pretty much what they are now. This doesn’t take into consideration the unusually quiet sun, which could affect things even more to the negative side.
How’s that for a “reasonable naive hypothesis”.
The thing is that you can’t force people’s wallets open to cure a problem that might, just maybe might be a problem in several centuries to a millenium. It has to be NOW NOW NOW OR WE ALL DIE!
An off topic question for Andrew (no offence Ira).
Why are there no ads or ‘donate’ buttons on the RC site?
Great article btw Ira (thumbs up)
Ian H says:
March 20, 2013 at 1:14 pm
“However we don’t know that it is still true today that temperature alone is driving CO2. “
Yes, we do. Or, those of use savvy enough to understand what this plot is telling us do.
Ian H says:
March 20, 2013 at 1:14 pm
“In fact trying to predict CO2 from temperature is the same kind of mistake as trying to predict temperature from CO2.”
I absolutely can predict atmospheric CO2 levels from temperature to high fidelity. It is right here. Over the modern era, I can integrate the affine temperature relationship and get it within about 4 ppm.
I can reverse it, and take the derivative of the CO2 to get temperature, but it is the integrated variable which must be the cause to the effect.
Bart says:
March 20, 2013 at 2:53 pm
“Over the modern era, I can integrate the affine temperature relationship and get it within about 4 ppm.”
I could do even better, centralizing the error, if I did an actual least squares fit to derive the affine relationship instead of just eyeballing. Furthermore, the datasets have varying fidelity. The best agreement appears to be with temperatures in the Southern Hemisphere, which suggests that this is mostly an oceanic phenomenon.
That is perfectly reasonable, since the oceans are a giant conveyor belt for CO2 with continuous flow (from hundreds of years ago) into the surface system in the tropics, and out of it at the poles. Any imbalance between those flows will either accumulate in the surface system, or drain out of it. And, that imbalance is absolutely temperature dependent, and would give rise to exactly the relationship we see of the rate of change of CO2 as an affine function of temperature.
“… while this simulation was not perfect, it has shown skill in that it has out-performed any reasonable naive hypothesis that people put forward in 1988 (the most obvious being a forecast of no-change)” ok im tired but it sure looks to me like that naiva hypothesis is less wrong then the applicable prediction
This might sound like a stupid question!
Is the Mauna Loa measurements of atmospheric CO2 measured by volume? if so can someone quantify the volume for me?
Robert Anton Wilson’s law of the priority of politics over science:
“If A is greater than B, and B is greater than C, then A is greater than C, except where prohibited by law.”
At the risk of being labelled a real denier what evidence do we have that the Mauna Loa seemingly exponential rise in CO2 is human induced? To be honest I would have expected to see some impact from the GFC.
e = mc^2: hint binomial expansion of srt( 1 – v^2 / c^2) from m1 = m0 * sqrt( 1 – v^2 / c^2 )
[DesertYote: OK, since I’ve been studying Time Dilation in connection with my What is Time? video, I recognize “srt( 1 – v^2 / c^2)” as 1/(Lorentz Factor). v is velocity of an object in Space and c is the speed of light.
An object moving at v appears to us, if we are “at rest” to have Length Contraction proportional to the Lorentz Factor and Time Dilation proportional to 1/(Lorentz Factor). Also, the mass of the object appears to increase by 1/(Lorentz Factor) which you state as “m1 = m0 * sqrt( 1 – v^2 / c^2 )” but I think you meant to write as “m1 = m0 * 1/(sqrt( 1 – v^2 / c^2 ))”.
The reason no object with Mass can get up to the speed of light in Space is that it would take infinite energy to get it up to that speed, apparently because, as its speed approaches c, its mass approaches infinity. You can see that, when v approaches c, and thus v^2 approaches c^2, v^2 / c^2 approaches 1, and 1 – v^2 / c^2 approaches 0, causing 1/, 1 – v^2 / c^2 to approach infinity.
So, since f = ma, and the Energy required to increase the speed of an object is proportional to f, then Energy is proportional to Force which is equal to m0 multiplied by 1/( 1 – v^2 / c^2) multiplied by a. OK, this is starting to look something like e = mc^2, but I am not quite there. Do you have a reference that will get me there? Ira]
Ira’s excellent point: “Even a “naive” prediction of no change would have been closer to the truth (low by 0.22 ⁰C) than Hansen’s Scenarios A (high by +0.68 ⁰C) and B (high by 0.53 ⁰C)!” can be made another way:
Suppose James Hansen had a contrary twin brother, Jock, who made the prediction at the congressional hearings – just after brother James (and turning the air conditioner back on as he came in) – that actually global temperatures would DROP from 1988 levels by .30 ⁰C on CO2 output Scenario B and by .45 ⁰C on CO2 output A. Jock’s COOLING predictions, though not borne out, would nevertheless be nearer to the realised outcome than those of his headline-grabbing warmist brother.
Come on down, Jock!
Greg House March 20, 2013 at 9:33 am:
Thanks for your comment. You clearly and collegially restate arguments put forth by many sincere and generally well-informed WUWT readers who cannot accept the basic science of the Atmospheric “Greenhouse Effect” or that H2O and CO2 and other Atmospheric gases are responsible for the Earth Surface being over 30 ⁰C warmer that it would be absent that effect.
You conclude with “Time to wake up, Ira, and look at those things really critically.”
I appreciate your concern for my being correctly informed. I have a similar concern for you. I would appreciate it if you, and others who are having a problem accepting the Atmospheric “Greenhouse Effect” as real would read my Visualizing series, here at WUWT.
There are five parts: Physical Analogy, Atmospheric Windows, Emission Spectra, Molecules/Photons and Light and Heat.
This series has garnered over 70,000 page views and 3000 comments at WUWT, mostly positive. I’ve learned a lot from WUWT readers who know more than I do. However, some commenters seem to have been taken in by scientific-sounding objections to the basic science behind the Atmospheric “Greenhouse Effect”. Their objections seemed to add more heat than light to the discussion.
My series was designed to get back to basics and perhaps transform our heated arguments into more enlightened understanding :^)
Please have a look at why I, while I definitely am properly SKEPTICAL about the entire CAGW Enterprise, and the unscientific antics of the ALARMISTS and some WARMISTS, nevertheless accept that the Atmospheric “Greenhouse Effect” is real.
Happy reading, then get back to me. OK?
Ira
Ira
I have read your comments with interest. Your articles are always thought provoking and objective.
My take on this is that unfortunately we do not have sufficient high quality data from which to form any firm view. Error bars in the data sets are not sufficiently identified and acknowledged and there has been a lack of empirical experimentation on the true effects of CO2 in real world conditioons and precisely what DWLWIR can achieve particularly with respect to its interaction with the oceans and the atmosphere immediately above the oceans (I refer to the atmosphere say a few metres above the ocean and the top centremeter of the ocean itself). Any proxy data needs to be considered with a high degree of caution. Unfortunately the thermometer data set is not fit for purpose; it was never intended to produce a record of global temperatures accurate to within tenths of a degree, and with siting issues, station drop outs and endless basterdisation by way of repeated adjustments the legitimacy of which is moot, it too cannot be used as a reliable base upon which to make reliable extrapolations. Indeed, the land based thermometer record is not even measuring the correct energy metric, and we lack proper data on clouds, albedo and solar irradiance.
As a consequence, we are very much left with a gut impression as to what is going on. My gut tells me that there is some GHE caused mainly by water vapour but it is very the GHE is much over hyped. I do not consider that we sufficiently understand solar irradiance and I consider that solar irradiance is probably sufficient in itself to prevent the tropical ocean from freezing. If that is so, then global temperatures even withoutb GHE would probably not be less than plus a couple of degrees. Accordingly, I consider the 30 degree C figure you cite for the GHE to be probably over hyped. I would not wish to put a figure on the GHE but I would not be surprised if it turns out to be only about a third of the figure that you suggest.
As regards CO2, I consider it likely that it plays some limited role over land (very much less over the oceans since water is a LWIR block) and I consider that it is likely that sensitivity varies both with temperature, prevailing water vapour and saturation. With today’s temperatures, and water vapour, I consider it probale that CO2 sensitivity is low. I would not wish to forcefully argue against your 0.25degC figure, maybe it is a bit more, but maybe it is a bit less. We simply do not know enough about natural variation to make a good stab, but I would be reluctant to argue against your figure being a good ball park figure. My gut firmly riles against positive feedbacks; quite simply planet Earth would not have enjoyed the relatively benign conditions that it enjoys today if feedbacks were positive and we would not be here today some 4.5 billion years after its creation blogging on this topic if feedbacks were positive.
Of course, being sceptical, I cannot rule out the possibility that the entire underlying science is fundamentally flawed. If only there had been some proper empirical experimentation on some of the fundamental issues raised, we would have a better understanding of whether that might or might not be the case.
[richard verney: Well stated. Although I am quite a bit less skeptical than you on the basic science of the Atmospheric “Greenhouse Effect” I cannot object to anything you say here. The data is not accurate to support precision of anything like tenths of a degree, and the Climate System is far too complex to model or predict to that type of precision. As engineers, we understand the difference between precision and accuracy, and the fact that precision to more significant figures than is supported by the underlying accuracy is an illusion. Anyone who says they are absolutely sure about any of this stuff is almost certainly wrong :^). Thanks for this useful and collegial interchange of ideas and opinions! Ira]
Ira Glickstein, PhD says:
March 20, 2013 at 4:39 pm
Greg is one of those people who believe the whole idea is simply false. And, that is simply false.
But, there are serious criticisms of the GHE. Not that it does not exist, but that it is not necessarily monotonic. The GHE can exist while being locally insensitive to additional GHG.
I went over Mauna Loa’s method of measuring CO2, they process the air, remove water vapor, do a bunch of fatally flawed conversions, bounce inferred light of a box full of processed dry air and measure an electrical response, then they convert this electrical measurement into a mole fraction of dimensionless quantity and redefine what Air is, they shift the figures about and give lengthy BS about why and after they have their data, they further process it by calibrating it with other data (who calibrates their data? Mauna Loa?). Then When they model the calibrated data to produce a graph that say’s PPM, they are dishonest and call it Atmospheric CO2. They give the impression that what they have measured is the volume or effective volume of CO2 in the atmosphere, It is NOT.
They say so themselves “Most people assume that we measure the concentration of CO2 in air, and in communicating with the general public we frequently use that word because it is familiar”
This process can be controlled even inadvertently to produce results that give the impression of an increasing mole fraction over a time scale by processing normal variability, effectively the processed data produced is artificial and can in no-way be used to quantify what atmospheric CO2 is on the planet, (and I certainly wouldn’t use it to predict future climate temperatures) What can you measure an artificial value to?
It also seems that there are assumptions built into their data of fossil fuel use, just like the CO2 based climate models.
This is the actual effective forcing numbers that Hansen used.
http://www.realclimate.org/data/H88_scenarios_eff.dat
If you compare that to what IPCC AR5 is using for the increase in net forcing since 1984 (RCP 6.0 scenario which is the most realistic trend), it is almost identical to the increase in forcing Hansen used in Scenario B. So B was an accurate description of the forecing which actually occurred (despite the spin from RealClimate or Skeptical Science).
http://www.pik-potsdam.de/~mmalte/rcps/data/RCP6_MIDYEAR_RADFORCING.DAT
http://www.pik-potsdam.de/~mmalte/rcps/data/RCP6_MIDYEAR_RADFORCING.xls
Couple of other Hansen 1988 data sources; temperature anomalies under the scenarios and the GHG concentrations.
http://www.realclimate.org/data/scen_ABC_temp.data
http://www.realclimate.org/data/H88_scenarios.dat
Scenario B temp in 2012 +1.065C GISTemp +0.560C
Predicted increasein temps +0.983C Actual increase GISTemp +0.44C
Hansen also updates his own 1988 predictions here.
http://www.columbia.edu/~mhs119/Temperature/T_moreFigs/PNAS_GTCh_Fig2.gif
Regarding Hansen’s ABC emission scenarios, here is an insightful comment at Climate Audit a few weeks ago-
Climate Audit comment, 03/02/2013
Kurt in Switzerland
“Ref. Scenario B being the most reasonable comparandum to actuals:
I disagree. Scenario A corresponds to 1.5% annual CO2 emissions growth. Actuals have been about 1.9% per annum since 1990, i.e., above Hansen’s Scenario A.
Hansen’s CFC growth rate for Scenario A was 3% p.a.
The additional 0.4% p.a. growth rate in CO2 would compensate for the lack of CFC growth rate, nest-ce pas?
Furthermore, Hansen’s Scenario B called for the growth rate of CO2 emissions to decline from 1.5% per year {1988} to 1% per year in {1990}, 0.5% per year {2000} and 0.0% per year {2010}. Clearly this didn’t happen.
From a cursory look at Hansen et al 1988 Appendix B, the estimated forcing due to both CFC’s mentioned (F-11 and F-12) rising from 0.0 to 2.0 ppb is about 1/4 that due to CO2 doubling (315-630 ppm). The lack of this should approximately cover the underestimate of CO2 emissions growth.
I’ll consider CH4 second order (and much tougher to calculate). Given all the media screaming about methane clathrates being “freed” due to unprecedented arctic warming, one would think actual methane emissions had exceeded Hansen’s worst fears.
So Scenario A is the closest to reality, not Scenario B (it would seem to me).
Either that, or the net UPTAKE by the atmosphere as a result of said emissions was poorly estimated. But that would be a different story. Hansen’s Scenarios are defined primarily by human emissions, not by atmospheric concentration per se.
Kurt in Switzerland”
Ira Glickstein, PhD says, (March 20, 2013 at 4:39 pm): “I appreciate your concern for my being correctly informed. I have a similar concern for you. I would appreciate it if you, and others who are having a problem accepting the Atmospheric “Greenhouse Effect” as real would read my Visualizing series, here at WUWT. … This series has garnered over 2000 comments at WUWT, mostly positive. I’ve learned a lot from WUWT readers who know more than I do. However, some commenters seem to have been taken in by scientific-sounding objections to the basic science behind the Atmospheric “Greenhouse Effect”.”
============================================================
“Basic science”, Ira? Let me give you an example. 2×2=4 is basic math. 2×2=5 is not basic math, it is not science at all, it is false. I do not think there is a reason to call warming by back radiation (this is the “greenhouse effect” as presented by the IPCC) is science. It is false, Ira. Of course, you are entitled to a different opinion.
To your articles, I am already familiar with the concept of “warming by back radiation” and find it proven false both on theoretical and experimental level. As I said, on the experimental level it has been known since the R.W.Wood experiment, maybe you need to read his paper. It is really easy reading. Second, on the theoretical level in a certain case of a body at a stable temperature starting receiving back radiation according to the “greenhouse effect” concept, the result would be that more energy is radiated away then there is in the system, and this proves that the initial assumption (“greenhouse effect”) is false.
I guess I’d better not wait till you start digging yourself and give you a link to that second point. Note that it is about a theoretical setup our beloved Willis invented to illustrate how “greenhouse effect” is supposed to work: a planet with a constant internal power supply surrounded by a sphere. Here is the link to my comment about that on another blog: http://climateofsophistry.com/2013/03/08/the-fraud-of-the-aghe-part-11-quantum-mechanics-the-sheer-stupidity-of-ghe-science-on-wuwt/#comment-828. Well, the actual post starting that thread is overheated, but please, focus just on the scientific point.
[Greg House: I have read and considered the R. W. Wood experiment material and nevertheless remain convinced of the basic truth of the Atmospheric “Greenhouse Effect” and that the radiation exchanged between the Earth Surface and the “Greenhouse Gases” in the Atmosphere has been properly accounted for.
However, as I expressed above in my agreement with Richard Verney, I do not accept the levels of precision claimed by some Climate Scientists. That is why my estimte of Climate Sensitivity has such a large range, from 0.25 ⁰C to 1 ⁰C, and, even my high estimate is a factor of three less than the IPCC and a fourth of Hansen 1988. It is also why I think net warming since 1880 is closer to 0.5 ⁰C than the 0.8 ⁰C or higher claimed by the official Climate Team (“hockey team”).
So, I side with “our beloved Willis” and the proprietor of WUWT, and scientists such as Roger Pielke (Sr and Jr :^), and the other skeptics and lukewarmers who seem to me to have taken a detailed and rational approach to this subject area. Ira]
Bart says:
March 20, 2013 at 10:31 am
>>>>
richard verney says:
March 20, 2013 at 8:37 am
“If one looks at the 33 years of satellite data then there would appear to be no first order correlation between temperature rise and the rise in CO2 emissions.”
But, there is a definite correlation between the rise in CO2 concentration and temperature.
//////////////////////////////////////////////////////
Your referenced data, proves my point. No mathematician worth his salt would plot a straight linear line through the temperature anomalies between 1977 and end of 2012. A mathematician would look at that data set and say that there is an approximate straight line fit at around the +0.12C level for the period 1977 to 1996 and another straight line fit at around the +0.18C level for the period 2000 to end of 2012. The mathematician would note the anomaly around 1997 to 1999 where a step change takes place; that step change is not brought about by CO2 unless CO2 caused the super El Nino of 1998 and as I said, no one suggests that CO2 levels were responsible for that event.
If you wish to consider the point I made in more detail I would suggest that you split your plot in two. First consider the period 1979 to say 1997 and then consider the period 1999 to date.
As far as your CO2 derivative, are you seriously suggesting that as a consequence of manmade CO2 emissions the global derivative in 1997 was 0.02 but in 1998 it was 0.31. What evidence is there for a manmade emission change of this order in the year 1997 to 1998. Please provide your data on annual manmade emissions supporting such a change in these years.
I think that what you are looking at when you are looking at in the CO2 derivative is a response, not a cause. The ocean heat release has out-gassed CO2. CO2 has not driven the temperature spike, but rather what you are seeing in the derivative is the CO2 response to the El Nino temperature change.
Bart says:
March 20, 2013 at 10:31 am
>>>>
richard verney says:
March 20, 2013 at 8:37 am
“If one looks at the 33 years of satellite data then there would appear to be no first order correlation between temperature rise and the rise in CO2 emissions.”
But, there is a definite correlation between the rise in CO2 concentration and temperature.
//////////////////////////////////////////////////////
Your referenced data, proves my point. No mathematician worth his salt would plot a straight linear line through the temperature anomalies between 1977 and end of 2012. A mathematician would look at that data set and say that there is an approximate straight line fit at around the +0.12C level for the period 1977 to 1996 and another straight line fit at around the +0.18C level for the period 2000 to end of 2012. The mathematician would note the anomaly around 1997 to 1999 where a step change takes place; that step change is not brought about by CO2 unless CO2 caused the super El Nino of 1998 and as I said, no one suggests that CO2 levels were responsible for that event.
If you wish to consider the point I made in more detail I would suggest that you split your plot in two. First consider the period 1979 to say 1997 and then consider the period 1999 to date.
As far as your CO2 derivative, are you seriously suggesting that as a consequence of manmade CO2 emissions the global derivative in 1997 was 0.02 but in 1998 it was 0.31. What evidence is there for a manmade emission change of this order in the year 1997 to 1998. Please provide your data on annual manmade emissions supporting such a change in these years.
I think that you will find that what you are looking at in the CO2 derivative s a response, not a cause. The ocean heat release has out-gassed CO2. CO2 has not driven the temperature spike, but rather what you are seeing in the derivative is the CO2 response to the El Nino temperature change.
Dr. Will Happer (Physicist), Princeton: “I have spent a long research career studying physics that is closely related to the greenhouse effect. Fears about man-made global warming are unwarranted and are not based on good science.”
Dr. Lee C. Gerhard (Geologist), UN IPCC expert reviewer: “I never fully accepted or denied the anthropogenic global warming (AGW) concept until the furor started after [NASA’s James] Hansen’s wild claims in the late 1980s. I went to the scientific literature to study the basis of the claim, starting at first principles. My studies then led me to believe that the claims were false, they did not correlate with recorded human history.”
Dr. Nicholas Drapela (Chemist): “My dear colleague [NASA’s James] Hansen, I believe, has finally gone off the deep end… The global warming ‘time bomb,’ ‘disastrous climate changes that spiral dynamically out of humanity’s control.’ These are the words of an apocalyptic prophet, not a rational scientist.”
Now *that’s* a model that doesn’t need updating…..
Hansen’s Scenario A appears to be the best fit for CO2 emmissions but I’ve heard it be argued by lukewarmers that scenario B is preferred because scenario A includes increasing levels of CFCs which instead have decreased thanks to the Montreal Protocol which applied from around the time of the prediction.
So to accept Scenario B is the most apt means accepting that CFCs had about as much impact on the climate as CO2 did. That doesn’t seem very plausible to me and so I think Hansen’s scenario A is closer to his true prediction than Scenario B is.
As I said, on the experimental level it has been known since the R.W.Wood experiment, maybe you need to read his paper. It is really easy reading.
>>>>>>>>>>>>>>>>>>>>
What the Wood experiment demonstrates is precisely the same thing that Mann’s hockey stick graph demonstrates. That, on both sides of the debate, there are those who justify their world view on the flimsiest of evidence and cling to it in the face of overwhelming factual evidence to the contrary.
This graphic – with excerpts from the recent Marcott paper is it appears, pretty intresting.
When you match the main Marcott temp history graphic and compare with graph “D” the ice core GHG measured Radiative Forcing, things get interesting. The thin green line is 1950 (“present” for BP) .
The GHG measured Radiative Forcing bottomed appx 8000 years BP andwere relatively flat for appx 1000 years, after which they began, and have continuing, climbing – relatively uniformly – since. About 2000 years BP the radiative forcing level flattened, similar to 8000 yr BP – until a sharp increase between 1000 and 800 years BP – after which – from 800 years BP to end of data the GHG measured radiative forcing was decreasing.
What is interesting to me – is that at a virtually identical times; the GHG measured radiative forcing bottomed and began climbing, AND there is a clearly defined warming pulse/peak in the Marcott data. Since that time GHG measured radiative forcing has been increasing while the Marcott demonstrated temps have been decreasing.
It is also interesting that the same pattern seems to exist at the 8000-7000 yr BP and 2000 to 1000 yr BP points. The GHG measured radiative forcing flattens for appx 1000 years, during which time (7000 and appx 1200 yrs BP) there is a noted, short lived temp spike, followed by accelerated cooling.
In the time period appx 50 to -50 yrs BP (1900-2000) – ignoring the Marcott “spike” which it appears is not supported by the data, we see a similar warm spike beginning in the Marcott graphic. We also know this matches the temp record for the same period, with temps reaching a peak appx 1997 and leveling since.
Despite that GHG measured radiative forcing increased from 7000 BP thru the end of the data poresented, and that we know GHG’s have continued to increase steadily the last 100 years and more, Marcott shows overall temps have continued to fall from the peak appx 7000 BP.
We also know that after climbing from late 1800 thru late 1990’s, while GHG’s continue their rise, temps have leveled for the last appx 17 years.
While this is admittedly “eyeball” science – and assumes Marcotts charts are accurate, it certainly appears Marcott shows that GHG measured radiative forcing is clearly not a driver of temperatures – at least not a driver of temp increases.
Or I could be missing something altogether … 😉
http://tinyurl.com/marcott-ghg