A Strange Problem with the IPCC Numbers

Guest Post by Willis Eschenbach


The IPCC says that the expected change in temperature arising from a change in forcing is equal to the change in forcing times the climate sensitivity. The IPCC provides values we can use to estimate the total human and natural forcing change since 1850. The IPCC also proves estimates for the climate sensitivity. These can be multiplied to provide the IPCC expected temperature change since 1850. The value derived (best estimate per IPCC numbers = 1.4 °C warming since 1850) is twice the observed warming (HadCRUT best estimate = 0.7°C warming since 1850).

Recently I became puzzled by what seems to be a glaring discrepancy in the official IPCC numbers. The IPCC estimate of climate sensitivity is +3 [+2 to +4.5] °C per doubling.

We also have the IPCC estimate of the change in forcing since 1750, in Watts per square metre (W m-2). The human contribution to that forcing is given by the 2007 IPCC Summary for policymakers as:

The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR), leading to very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming, with a radiative forcing of +1.6 [+0.6 to +2.4] W m-2.

This represents the best estimate plus [lower and upper bounds].

Now, a doubling of CO2 is estimated by the IPCC to produce a change in forcing of 3.7 W m-2. So if we divide the climate sensitivity (in degrees per doubling) by 3.7, we will get the climate sensitivity expressed in units of degrees per W m-2. This gives us the result:

Climate Sensitivity = +0.8 [+0.5 to +1.2] degrees per W m-2.

Finally, we know that sensitivity times the change in forcing gives us the temperature change. Using the IPCC estimates of both, this gives us:

+0.8 [+0.5 to +1.2] degrees per W m-2   times   +1.6 [+0.6 to +2.4] W m-2

= +1.3 [+0.4 to +2.2] degrees of warming from human activities since 1750. (Errors throughout have been assumed to add in quadrature.)

Now, we don’t have very good temperature data before 1850, so we need to adjust for that. However, there was very little human effect on the climate from 1750 to 1850. CO2 levels were only slightly lower in 1750 than in 1850, the industrial revolution was in its infancy, little fossil fuels were burnt, sulfur emissions were negligible, no fluorocarbons were emitted. Since the 1750-1850 anthropogenic contribution is very small compared to the total anthropogenic forcing, that IPCC based calculation of temperature change from humans of +1.3 [+0.4 to +2.2] degrees can be taken as the best estimate and bounds of the human caused temperature change since 1850.

For our final estimate, in addition to the human forcings since 1850 we need to add the natural forcings. The IPCC includes only one of these, solar forcing. The IPCC estimates that changes in solar forcing in the ~250 years since 1750 was 0.12 W m-2. For our rough calculations, we can make a crude but adequate estimate that three fifths of this change occurred since 1850. Adding solar forcing to the earlier equations makes the IPCC calculated temperature change from human and natural forcings combined since 1850 slightly greater, at +1.4 [+0.4 to +2.3] degrees.

Now, here’s the problem with that, and it’s a very big problem. According to the HadCRUT dataset (monthly dataset here, with notes here), the total temperature change 1850 – 2006 is +0.7 [+0.5 to +0.9] degrees. In other words, the world has warmed by around three-quarters of a degree (best estimate 0.7°C) since 1850. That’s nowhere near 2.3°C, the high end of what the IPCC says should have happened since 1850. It’s only half of the IPCC’s most likely number. It is just above the IPCC’s lower bound. So the IPCC method, using the IPCC numbers, way overestimates the historical temperature rise.

What can we conclude from this mismatch between observations and calculations? There are a number of possible explanations, in no particular order.

1. The sensitivity numbers are too high, and the forcing numbers are correct. If that is the case, the  sensitivity is +1.5 [+0.5 to +2.4] degrees per doubling of CO2, a much lower and narrower range than the +3 [+2 to +4.5] range espoused by the IPCC.

2. The forcing numbers are too high, and the sensitivity numbers are correct. That gives us a calculated change in forcing since 1850 of +0.9 [+0.5 to +1.4] W/m2. Again this is much lower and more narrowly bounded than the canonical IPCC range of +1.7 [+0.7 to +2.5] W/m2 including solar. Note that in both this and the previous case, the relatively narrow bounds of the temperature observations have constrained narrow bounds on the underlying forcings or sensitivities.

3. Both the sensitivity and the forcing numbers are too high. This would limit possibilities to values such that the product of the two give us +0.7 [+0.5 to +0.9] degrees of warming. If the reductions were proportional, the forcing and the sensitivity would each need to be cut to about 70% of the IPCC numbers.

4. There are other mechanisms at play (e.g. cosmic rays, plankton aerosol production, thunderstorms) that the IPCC is not accounting for.

5. I’ve made a foolish mathematical mistake.

6. Climate may not obey a linear relationship between forcing and temperature change. My calculations are based on the IPCC assumption that a change in temperature can be calculated as a constant called “climate sensitivity” times the change in forcing.  However, climate sensitivity may not be (and in my view is not) a constant. Instead, in my view climate sensitivity is a function of T, which changes the equation.

7. This is the “missing heat” that Trenberth referred to.

8. Something completely different that I haven’t thought of.

I couldn’t even begin to say which of those, or how many of those, if any of those, are actually going on …

Anyhow, that’s the oddity. If we multiply the IPCC historical forcing change since 1850 times the IPCC climate sensitivity to get the IPCC estimated temperature change since 1850, the result is nothing like the historical temperature change. The high IPCC estimate (2.3°C) is three times the actual change (0.7°C) since 1850. Clearly, something is wrong. Depending on which explanation we choose, we have different conclusions, none of which seems compelling.

Assistance and ideas welcome …

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richard telford
October 23, 2010 4:08 am

You are assuming that the climate is in equilibrium with the forcings.
Look at the committed projection in the AR4 report. There is still more warming expected even if forcings are held constant.

October 23, 2010 4:18 am

I think that; “5- I’ve made a foolish mathematical mistake”, fits the bill.

October 23, 2010 4:24 am

Dear Willis
I cannot find your email address. If you can send it to to me
(tcurtin (at) bigblue.net .au)
I will be able to respond with my paper just submitted to RES (UK) and Economic Papers (Australia). I need your comments!

John Marshall
October 23, 2010 4:25 am

Figures plucked out of thin air! We have atmospheric CO2 content for the 1850’s and later which are between 400 and 520ppmv. Way above today’s 385. It was colder back then as the planet was recovering from the LIA. The IPCC assume that pre 20th cent CO2 content was 250-285ppmv which on the old figures is completely wrong. Their low CO2 figure is there to prove that we are heating the climate.
You can always prove your assumptions if you use incorrect data.

October 23, 2010 4:26 am

Excellent overview based on a scientific approach: result: as expected more reasonable and required questions!

Josh Grella
October 23, 2010 4:31 am

I think the answer is obvious. The IPCC does not know what they are talking about when it comes to the overall contributions of all the various factors that are invovled in climate. In fact, they don’t know all the factors, nor do they care to know/understand them. Their real objective has always been about control of people and redistribution of wealth. That’s why they have focused solely on the emissions from fossil fuels and have ignored everything else. Control energy and you control wealth and progress.

David Brewer
October 23, 2010 4:32 am

The explanation will be ocean delay. IPCC models have atmospheric warming taking 30 years or so to show up after atmospheric forcing, mainly because the oceans “dampen” the effect. So the temperature change up to now represents the forcing accumulated up to about 1980, in their view.

Roger Knights
October 23, 2010 4:40 am

Didn’t Monckton make a similar (or identical) criticism?

October 23, 2010 4:46 am

Does this mean that its worse than we thought?

Luis Dias
October 23, 2010 4:57 am

Aerossols. For crying out loud, read the damn IPCC report.

October 23, 2010 4:58 am

David Brewer: I think you’re right that “ocean delay” would be the explanation. But it’s looking less and less likely since the OHC trend has been flat for several years now. See e.g. http://bobtisdale.blogspot.com/2010/10/update-and-changes-to-nodc-ocean-heat.html

Dr T G Watkins
October 23, 2010 5:04 am

Always enjoy Willis’ postings.
Warren Meyer at Climate Skeptic has pointed out the inconsistencies in his excellent reviews some time ago but the more the numbers are exposed the better.

October 23, 2010 5:05 am

never heard something about thermal interia of the oceans????
See for example Wetherald et al. 2001, ” Committed warming and its implications for climate change”

Nullius in Verba
October 23, 2010 5:10 am

I think you’re talking about the difference between equilibrium and transient sensitivity. Warren Meyer noted this same discrepancy ages ago in his video.
The problem with high sensitivities is that we’ve already seen half a doubling (logarithmically speaking), so we ought to be seeing half the predicted warming. Clearly we’re not. So to explain that, they have invented lags and time delays that shift the consequences decades into the future. This is what the storage of heat in the oceans was supposed to achieve. Their idea is that even if you stopped changing the CO2 level now, and held it constant at the current level, the temperature would still continue to go up, until it reached the equilibrium level.
This is part of the three steps to catastrophe – first, construct a model with very high sensitivity; second, explain why the warming that ought to result from it did not occur in the past; third, explain why these blocks will cease to apply some time over the next century.
This is why model sensitivities are not falsifiable – whatever sensitivity you pick, the other parameters can be adjusted to fit observations.

Nigel Brereton
October 23, 2010 5:11 am

baffled24 – I fail to see the significance of your link!
‘Now, a doubling of CO2 is estimated by the IPCC to produce a change in forcing of 3.7 W m-2’
What is the actual change in CO2 during this period aprox 280-380 ppm? Do we need to factor the 3.7 Wm-2 by this amount?

Golf Charley
October 23, 2010 5:14 am

The models are right, it is the earth that is wrong. If the data doesn’t match reality, change the data. But make sure no one finds out.
Paleoclimatology doesn’t match history, so change history. But make sure no one finds out.
It is man’s emissions of CO2 that make the earth wrong. Make sure everyone knows that this is a fact.

October 23, 2010 5:23 am

In your first point, it should be more like [+1.0… instead of [+0.5…
John M Reynolds

Dave Springer
October 23, 2010 5:28 am

baffled24’s response is useless. The link he gave only confirms the .7c temperature rise from 1850 via Hadley CRU. No wonder the child is baffled.
Your math appears to be correct. Trenberth agrees that half the expected heat is missing. Actual temp rise (if HadCRUT3 is correct) is .7C while IPCC mid-range projection for that amount of forcing is 1.4C. To be fair .7C is the lower IPCC bound. Trenberth evidently doesn’t believe the lower bound is correct.
The larger issue here seems to be that these calculations are all about CO2 doublings whereas CO2 accounts for 50% or less of anthropogenic forcings with methane and black carbon accounting for most of the other half.
So I’m not sure what exactly is referred to by a “doubling”. If it’s truly CO2-only then the expected warming even at the low-end of IPCC figures is twice as high as measured warming. The amount of missing heat is worse than Trenberth thought. Adding insult to injury the amount of methane in the atmosphere is increasing twice as fast as CO2.
The reason methane and black carbon are swept under the rug is because the United States can’t be blamed for those. The U.S. emits very little of these as it cleaned up the black carbon particulates by law beginning with the Clean Air Act of 1963 and it doesn’t produce much rice which is the single largest world-wide source of methane. So-called “developing” nations are responsible for most of the methane and black carbon emissons but it’s politically incorrect to assign any blame to them so CO2 is the designated boogeyman and because (up until about 2008 when China became the biggest emitter) the U.S. was the largest emitter of CO2 it becomes the designated scapegoat for global warming. Making the United States of America the nation responsible for global warming is the whole point of the CAGW agenda. Most of the world and evidently half the U.S. electorate as well believes the United States is too powerful, too wealthy, too arrogant, and too willing to flex its muscle around the world and they desperately want that to change in a big way. Hobbling the U.S. economy by making it pay dearly for every ton of CO2 emitted while giving “developing” countries a free pass to keep on growing their emissions of CO2, methane, and black carbon without restriction will accomplish their goal. Thankfully US leaders up until now (primarily Clinton, GW Bush, and congresses during those administrations) saw straight through this charade and refused to ratify the Kyoto Protocol. Obama and the current congress in their zeal to appease the rest of the world might actually throw US GDP under the bus to do it. The US electorate however appears as recalcitrant as ever so the elected leadership is well enough aware they’ll be replaced before any actions they take could be implemented. Given it looks like they’re going to be replaced anyway in a few days it’ll be interesting to see what they try to shove through in the lame duck session between now and January since they’ll have nothing left to lose.

Mike Davis
October 23, 2010 5:35 am

You are not using the correct “Math”!
Your math: 2+2=4!
Climate Math: 2+2=6!
There is an “Esoteric” formula for that and your not being among the enlightened is why you got it wrong!

Niels A Nielsen
October 23, 2010 5:42 am

The explanation is the ocean lag, the heat capacity of the great oceans. I’m sure you heard about the “heat in the pipeline”. Go to Pielke Sr for interesting discussions about the concept. The cooling of the oceans in recent years makes it increasingly doubtful that there is much if any “heat in the pipeline”, though.

October 23, 2010 5:47 am

Thanks Willis for your great post. I always learn so much from you – clear explanations, logical progression of argument – its really appreciated.
Personally I wish I knew more about the changes in Land Use / Land cover over time. Because I suspect that we are tilling more land now than in 1750 or 1850 (or 1950 for that matter) – which have an effect in the size of an important carbon sink. Are changing sizes of sinks accounted for?
It seems to me that a small change to that huge reservoir could have a colossal impact on things too.

October 23, 2010 5:49 am

Epicycles, old boy. If you are not seeing what fits with the theory, you merely add something. With planetary motion, it was epicycles. With climate, well maybe it is aerosols. Or missing heat stored secretly in the ocean, waiting to pounce. I am not quite sure of the mechanism whereby today’s excess heat is somehow going into the ocean, not the sky, but I’m sure there is a peer-reviewed paper. Otherwise it would be a travesty.

Vince Causey
October 23, 2010 5:49 am

You forgot to include the radiative imbalance. Hansen’s figure is about 0.8 W/square metre. I understand this reflects the lag between forcing and equilibrium. I’m not sure what affect that would have on expected temperature rises though.

October 23, 2010 5:53 am

I’m surprised you don’t have enough “FAITH” in the IPCC numbers to “SEE” where the “TRUTH” is without the aid of math and human reason. Alas, true faith is not given to all; many are called, but few are chosen. (-;Sarc Off;-)

David L. Hagen
October 23, 2010 6:03 am

4. There are other mechanisms at play . . . that the IPCC is not accounting for.

Especially the 60 year Pacific Decadal Oscillation (PDO). Easterbrook shows past trends are dominated by PDO driven cooling/warming and projects similar temperature trends through 2010 which are markedly below IPCC trends. See:
Don Easterbrook’s AGU paper on potential global cooling

8. Something completely different that I haven’t thought of.

Climate is stable and the true feedback is negative. The transition from one stable configuration to another stable configuration appears to give positive feedback. (Will give ref when I find it again). IPCC’s positive feedback is unrealistic – it projects runaway temperature, contrary to evidence of previous multiple glacial periods.
Prior interglacial temperature inferences show we need to be concerned over global cooling not warming. etc.

Michael Jankowski
October 23, 2010 6:07 am

IPCC says “net effect of human activities,” which would assume to include aersols and their supposed cooling effects. Then again, that also would include warming from land use changes, other GHGs, etc.
At any rate, comparing “net effect” to that solely from CO2 might be a little apples-to-oranges.

October 23, 2010 6:16 am

The effect of CO2 is logarithmic but linear will give a decent approximation.
The old chestnut about the heat building up in the oceans doesn’t appear to be true. So where is the warming in the pipeline hiding and better yet when will it emerge !
If it is hiding at the bottom of the ocean and will emerge in 1,000 years who cares ?

Joe Lalonde
October 23, 2010 6:17 am

Science is so focused on temperatures that a great many other “insignificant” facts are being missed and pushed aside. CO2 itself IS changing our weather without factoring ANY heat.
This planet in being over-pressurized.
Growth up in the mountainous areas.
Average wind speeds decreasing.
Ocean salinity changes.
Increased heavy precipitation.
Increased storm strengths.
Incorrect theory that oceans cause hurricanes and cyclones when oceans have no wind to contribute, just precipitation.
The clouds being compressed by atmospheric changes.
These all add up to the displacement of regular molecules that stay close to the planet surface with a more dense/heavier molecule CO2.

October 23, 2010 6:19 am

Off topic:
Scientific American reports a massive coral bleaching event off SE Asia. It’s interesting that SA has moderated its tone of cock-sure certainty (that it had a couple of years ago) about AGW being clearly to blame for all such events, and now headlines the article with the question: “Is climate change to blame?”

October 23, 2010 6:22 am

Thank you for your clear post and for your interest in checking the numbers.

Charlie A
October 23, 2010 6:24 am

As several commenters have said above, the error in your very basic calculation is that the sensitivity numbers are for equilibrium. Or to put it another way, the heat capacity of the oceans slows the response.
This is just another example of why the OHC (ocean heat content) is the preferred metric for global warming. Over a given period (1 year for example), the change in ocean heat content is a direct function of the overall radiative forcing over that period.
Obviously incorrect, oversimplified calculations of just multiplying the radiative forcing time the equilibrium sensitivity are counter-productive.

Bill Illis
October 23, 2010 6:37 am

Trenberth did comment on this on two different papers.
One, which hasn’t been taked about much, has a more revealing chart which adds to what Willis is talking about and adds another section to the IPCC bar chart of Anthropogenic forcing – the feedbacks.
+ 1.6 W/m2 of anthro forcing;
+ 2.1 W/m2 of feedbacks which should be there;
– 2.8 W/m2 of mysterious negative radiative feedbacks that we don’t know how are occuring;
net +0.9 W/m2 which gives +0.7C (using the 0.81C/watt/m2 formula used by the IPCC)
Sometimes, the IPCC and Hansen quote a sensitivity about how much temperatures will rise for a given 1 Watt/m2 of Anthro forcing – which is usually quoted as +0.75C to +0.81C per 1 Watt/m2.
But this amount is before feedbacks (the IPCC and Hansen assume there will be 200% of additional feedbacks per 1 additional Watt/m2 of Anthro forcing – feedbacks including water vapour, ice albedo and vegetation albedo).
And these feedbacks take 25 years to fully materialize. A large amount occurs almost immediately, another large amount in the first 7 years and then the feedback factor starts to fall off (but the theory says they will continue building for up to 1000 years).
How much do temperatures actually increase per 1 Watt/m2 of forcing – there is only about a dozen numbers one could use.
– 0.18C/watt/m2 – the Stefan Boltzmann equation for the surface;
– 0.265C/watt/m2 – the Planck Response for the tropopause;
– 0.42C/watt/m2 – the short-term-less-than-one-year transient response the climate models use for a given 1 watt/m2 of Anthro forcing after feedbacks;
– 0.75C to 0.81C/watt/m2 – the medium-term equilibrium response from the theory for a given 1 watt/m2 of Anthro forcing after feedbacks have fully adjusted; and,
– 1.5C/watt/m2 – the long-long-term equlibrium response starting to be accepted as the full equilbrium response for a given 1 watt/m2 of Anthro forcing after about 1000 years.
We are actually much closer so far to the very lowest number above.

October 23, 2010 6:39 am

Ocean delay, aerosols, fairies; sounds like massive hand waving to me.

October 23, 2010 6:40 am

IPCC magic trick goes something like this:
Cup #1: 1.4° F
Cup #2: 0.7° C
Shuffleshuffleshuffle . . . shuff.
Cup #1: 1.4°C
Cup #2: 0.7° F
Taaa . . . Badabadabadabum . . . da.
That’s climate change live for ya’ll and that’s all folks.

October 23, 2010 6:47 am

My career, funding and reputation are hitched to the hysterical global warming movement.
My numbers don’t support my choice of theories to support
Gradually, science is replaced by the the need to cover my backside.

October 23, 2010 6:49 am

You appear to have omitted ‘aerosol cooling’ [Figure 2.4 of AR4]: 0.5 W/m^2 direct; 0.7 W/m^2 indirect [clouds]. Recent work suggests the direct effect may be 0.3 W/m^2. I believe the indirect effect is imaginary.
It’s because in 1974, Hansen and Lacis adapted an equation from Carl Sagan predicting cloud albedo from ‘optical depth’, inversely related to droplet size. Unfortunately, dark clouds, e.g. raining cumulo-nimbus, have largest droplets so Sagan’s simplification is wrong yet the calculation appears to be present in all models.
The justification seems to be that Twomey showed polluted thin clouds have higher albedo [but warned it didn’t work for thick clouds]. He also predicted 0.5 maximum cloud albedo. However, by about 2003, the cloud part of ‘global dimming’ couldn’t be proved experimentally and thick clouds were shown to have >0.5 albedo. The subject seems to have been in a quandary, retreat to sustainable science or bluff.
In 2004, Twomey was given a prize, fake physics purported polluted thick clouds have high albedo from a reflection process, e.g.: http://geo.arc.nasa.gov/sgg/singh/winners4.html , http://terra.nasa.gov/FactSheets/Aerosols/
Despite no experimental proof and no theory except for thin clouds, the ‘cloud albedo effect’ is 44% of median AGW in AR4. Without that correction, the IPCC’s predicted AGW should be nearly halved. But if you do that the models have to take into account heating from other than CO2, so in reality you must reduce it by a factor of c. three.
But, because the second optical process is strongly dependent on droplet size, the effect of pollution is to decrease albedo, another AGW. As it’s self-limiting, it may explain why as measured by ocean heat content, global warming stopped in 2003. So, net CO2-AGW may be still lower, even zero as predicted by Miskolczi.

John Whitman
October 23, 2010 6:52 am

Very educational for me. Thanks.
Nice touch at the end of your post to invite assistance & ideas. I will try.

October 23, 2010 6:54 am

Willis, Are you aware of the following http://www.rsbs.anu.edu.au/Profiles/Graham_Farquhar/documents/271RodericketalPanreviewIGeogCompass2009_000.pdf
Here, is something measured which has a greater impact than CO2!

October 23, 2010 6:59 am

Observations always trump models! Ergo ………………….

Noblesse Oblige
October 23, 2010 7:06 am

Aerosol cooling is supposed to mask much of the underlying warming. See for example Stephen Schwartz http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=1067
However, regardless of whether this is correct, we can say that the observed warming since 1850; the calculated forcings of all GHGs, aerosols, albedo, solar variabilty, etc., as provided in AR4, are not consistent with a sensitivity of 3 [2-4.5] deg. Something is indeed wrong, but the system has too many variables to determine what it is.

Robert of Ottawa
October 23, 2010 7:12 am

I think this reveals how simplistic and naive is this equation. The warmistas are just trying to blind the masses with scientific bafflegab.

R. Craigen
October 23, 2010 7:23 am

I’m not saying it’s the right one, but I like your inclusion of possibility #8. It’s often the unknown unknowns that come and bit you in the butt. Your “math” looks correct to me, but let’s be clear: It’s just arithmetic. Too often people invoke “math” when what they mean is that they did some arithmetic. Not the same thing.

Charles Higley
October 23, 2010 7:28 am

1) Does the IPCC believe that the warming since 1750 is all manmade. The planet gets no credit for coming out of a mini-ice age?
2) The IPCC altered (unilaterally and for no reason) a thermodynamic constant for CO2 (I cannot remember its name), bumping it up 12-fold, while lauding (some misdirection here) how constant this value had been in the literature (pretending it had been high the whole time).
If we go back to the real value for CO2, the 3 degC becomes 0.25 degC, making this a whole new ball game.
3) Do they assume CO2 has a linear effect? Is Beer’s Law being included in their fantasies about warming due to CO2 increase?
4) They say that they have a much better understanding of man caused warming when in fact they know virtually nothing as their assumptions are invalid from the beginning.

Roger Andrews
October 23, 2010 7:44 am

According to detailed estimates prepared by NASA-GISS (http://data.giss.nasa.gov/modelforce/RadF.txt) anthropogenic radiative forcings during the 20th century amounted to 1.8 watts/sq m, with almost all of this occurring after 1970.
According to my reconstruction of the global surface temperature record, surface temperatures increased by 0.75C during the 20th century, with almost all of this occurring after 1970 too.
According to the IPCC, “most” of this warming was anthropogenic, and I’m going to assume that “most” means two-thirds, or 0.5C. (Scafetta and West and Solanki come up with roughly the same number after subtracting solar irradiance impacts.)
And if 1.8 watts/sq m causes 0.5C of warming, then 3.7 watts/sq m, which is what we get from a doubling of CO2, will cause a temperature increase of slightly over 1C. Therefore the climate sensitivity is +/-1C. (The Lindzen estimate).
What’s wrong with this number? Nothing. It’s a reasonably robust empirical estimate, probably the best we can make using the data we have. So why isn’t it used? Because it shows a) that there were no significant feedback mechanisms operating during the 20th century, b) that there won’t be a huge temperature increase during the 21st and c) that the climate models that predict one are wrong.
Nothing wrong with your math, Willis.

October 23, 2010 7:47 am

On top of all this do we have to assume all the .7C increase is CO2 or other greenhous gas.?
What about UHI?
How about measurement error?
What about various natural cycles; if we have .2C cooling in the next 25 years where does this place the already poor IPCC numbers?

October 23, 2010 7:48 am

[Note: There is a Test page at the top of the home page. ~dbs, mod.]

October 23, 2010 7:50 am

I’ve tried to make the same argument in the past and was assured by warmistas that there is a 30-year lag at work.

Wilson Flood
October 23, 2010 7:51 am

I doubt if you can starting counting at 1850. The number of weather stations was so small then that the uncertainty of the data is huge. I maintain a HadCRUT3 graph using monthly not annual data. From 1850 to 1880 the graph is all over the place. However, you still have the problem of where you start counting. The 1800s seems to have been a cold century but if you start at say late 1870s there is hardly any warming but if you start at about 1890s there is more. If we had data for the 1700s we would get much less warming as the 1700s seems to have been a warm century. Same with starting at 1910 or 1940. This is not good science it is salesmanship. There is no correct place to start counting. It is rather like these investment packages which advertise huge value growth by starting at a stock market slump and ending in a boom. Move the chart a couple of years either way and you make no money at all!!!

J. Bob
October 23, 2010 7:51 am

Solaris says: “never heard something about thermal interia of the oceans????”.
If there is thermal inertia, due to the heat capacity of the ocean, then one would expect the global temperatures to continue rising. But over the past 8-10 years they have flattened out. Sort of contradicts the laws of thermal transfer.
Maybe there’s a thermal drain in the sea floor.

Wilson Flood
October 23, 2010 7:53 am

In reply to Luis Dias, most IPCC reports are indeed a load of aerosols.

October 23, 2010 7:55 am

“What can we conclude from this mismatch between observations and calculations?”
Models vs. Reality = Models always lose

Steve Keohane
October 23, 2010 8:10 am

Thanks again for a clear-headed analysis. I suppose if one were to take out a UHI influence there may be little to no sensitivity/warming at all.

old construction worker
October 23, 2010 8:15 am

Wow. Why don’t we go back in time and “heat” our homes in the southwest using swamp cooler as “heaters”. Isn’t that what the idea of CO2 forcing and water system feedback does?
Or better yet, why not go back using swamp cooler in high humidity to cool our homes.

Mike G
October 23, 2010 8:28 am

Well, the democRats can do a lot of damage during the lame duck session and they can pass all kinds of economy hobbling measures. Obama can agree to any treaty he wants to. One thing they can’t do is ratify any of these stupid treaties. The founders saw to that by requiring 2/3 of the senate.
Hopefully, the new house of representatives will shape a little of the future legislation to bring some of Pelosi’s stupidity home to roost on the morons in her district who keep re-electing her. That may be the only way to do anything about the entrenched ideologues who are working so hard to do away with the document that requires that inconvenient two-thirds majority.

October 23, 2010 8:47 am

A large radiative imbalance caused by ocean lag means there should be continuous warming of the oceans as they catch up to the equilibrium temperature. The data that shows they are not warming is in direct contradiction to the long lag time hypothesis.
Aerosols are so much fun. They can explain everything because our understanding is so poor. What is often missing from the aerosol discussion is the fact that black carbon could easily cause more warming then attributed and sulfites could cause less cooling then attributed making the climate sensitivity much less. Since when has ignorance become a convincing argument?

Jim D
October 23, 2010 8:54 am

I can’t believe Willis didn’t know about aerosols, volcanoes, global dimming, and he was probably just testing his readership by feigning ignorance. Areas where warming has been suppressed, mostly in the northern hemisphere, include as a most obvious example the SE USA, where the obvious effects of anthropogenic haze have been increasing between the 40’s and 70’s in conjunction with the oil industry. Some claim the PDO and AMO caused all of this, but I dispute that on geographical grounds as regards the southeast, which dominates the US average cooling.

October 23, 2010 9:15 am

Willis, when it comes to trolling for trolls, you da best! Amazing how these folks hover over the site and jump in with their views ahead of normal human beings! Your posts seem to roil the bottom and bring these odd creatures to the surface. Thanks.

Scott Covert
October 23, 2010 9:17 am

Mike Davis says:
October 23, 2010 at 5:35 am
You are not using the correct “Math”!
Your math: 2+2=4!
Climate Math: 2+2=6!
There is an “Esoteric” formula for that and your not being among the enlightened is why you got it wrong!
2+2=16 for very large values of “2”.

October 23, 2010 9:17 am

This post is perfectly timed for me. I have recently finished an analysis of the CO2 forcing and climate sensitivity and I found some serious flaws that cannot be reconciled. Using only AGW supplied information I have concluded that their sensitivity is much greater than possible. By only using their information.
Tomorrow I will post the analysis on my website. It is pretty good. Still touching up the article so I am giving myself time, but it should be a very good read. I am very curious what the response will be.
John Kehr

October 23, 2010 9:23 am

thank you for a step closer to truth! So sick of all the BS out there! love your blog.

October 23, 2010 9:40 am

I have a question for all you gw ‘computer ensemble’ programmers out there.
If the atmosphere contains 750 gigatons of carbon, and all 4,000 gT of known fossil fuel reserves were burned, the CO2 concentation would increase from 390 to 2,440 ppm, resulting in a logarithmic temperature increase of 1.5C. If we are burning 5.5 gT of carbon per year, the temp increase can only be about 0.002C.
How many people do you know own a thermometer that can measure this increase?

Leonard Weinstein
October 23, 2010 9:43 am

You forgot to include natural recovery from the LIA. About half of the temperature rise occurred before 1940, and almost all of that is considered to be natural rise. After 1940 the temperature went down then up. It is fairly obvious that the drop is not due to aerosols, since cycles up and down occurred before and are occurring after that period. The long period ocean currents and or solar variation are the likely cause. There is a reasonable chance much of the rise over the 1940 level is related to CO2 and other human causes, but when the cyclical variation due to the oceans (or whatever the cause) is accounted for, the human effect is almost surely less than 0.3 C. The cycle down is started, and projecting out to a doubling of CO2, possibly 0.3 C more might be caused by human activity. By this time, the use of fossil fuels should be almost stopped (due to greater difficulty getting it and thus increased cost compared to say nuclear). The basic point I make is that including natural recovery from the LIA, most of 0.7 C has to be dropped to about 0.3 C, and the models are even more wrong.

October 23, 2010 9:51 am

Perhaps I’m missing something, but I’ve often wondered what is the point of error bands if everyone ignores them and assumes the ‘mean’ of ‘median’ or some other value is the ‘correct’ one.
Since the IPCC are correct (i.e. the real data is within the error bands) then the theory is OK – perhaps someone needs to work one reducing the error bands.
Equally, the hockeystick, when shown with error bands, easily encompass the MWP, the LIA, and the missing recent increases, and in fact hardly looks like a hockeystick at all if you include the error bands.
So what are they for if they are always ignored?

October 23, 2010 10:02 am

Jim D says:
“Areas where warming has been suppressed, mostly in the northern hemisphere”
Actually it is the southern hemisphere that hasn’t been warming.

October 23, 2010 10:03 am

Thank you Willis. I have wondered at your patience to sift through these reports that are full of wild theories and outright fabrications. It occurs to me you have a natural inclination to teach. I appreciate the lessons you have brought forward and feel a small kinship with you in that in all things I want to see the numbers. Dont try to baffle me with discourses that imply I lack the intelligence to understand as I saw through that argument at the age of eight. What I see in the comments here does nothing to persuade me in agreeing to AGW. On the other hand I see Joe Lalonde qualifies for a grant worth camillions, the ocean heat sink theory needs a camillion dollar grant, etc. etc. I expect these reports to reach the high standard displayed by those paragons of virtue Hanson and Mann. I think I understand how the dark ages happened from watching what is going on today as these charlatans are at least with the likes of the al gores responsable for some of the dimming of the intellect of this generation.

Political Junkie
October 23, 2010 10:16 am

steveta_uk wonders:
“Equally, the hockeystick, when shown with error bands, easily encompass the MWP, the LIA, and the missing recent increases, and in fact hardly looks like a hockeystick at all if you include the error bands. So what are they for if they are always ignored?”
Your recollection of events may be different from mine, but it seems that the Hockey team and IPCC made a bit of a fuss about the hockey stick.
I don’t recall Mann saying: “Hey, our conclusions are well within the error bands, you can fit in any curve you feel like! Nothing to look at here.”

October 23, 2010 10:21 am

I’m pretty sure Pielke Sr. has refuted the “heat in the pipeline” hypothesis (aka Trenbeth’s Travesty), mentioned by several posters above. I don’t have the ref handy, or the time to find it now. Anyone?
TIA, Pete Tillman

P Walker
October 23, 2010 10:23 am

Jim D – I have lived most of my life in the SE US and have no idea what you’re talking about .

October 23, 2010 10:32 am

One great thing about numbers is they only work well when properly used.
Did the IPCC include flatulence from cows and bulls, that could account for the missing heat.
When arguments rigged to support theory are acceptable by authority there is no need for fundamental physical laws. It is depressing to see people with obvious ability use it in such a fashion.

Jim D
October 23, 2010 10:37 am

tty is wrong. The minimum in the 70’s is clearly a northern hemisphere phenomenon. Recent differences in rate of warming between the hemispheres can be explained by the larger ocean area in the southern hemisphere that has more thermal inertia. Look at the GISS temps for example.

October 23, 2010 10:39 am

The IPCC cherry-picked the highest forcing examples it could find, and declared them to be the global average.
Since when has that bunch ever made an honest attempt at getting an acceptable number?

October 23, 2010 10:40 am

old construction worker says:
October 23, 2010 at 8:15 am
“Wow. Why don’t we go back in time and “heat” our homes in the southwest using swamp cooler as “heaters”. Isn’t that what the idea of CO2 forcing and water system feedback does?
Or better yet, why not go back using swamp cooler in high humidity to cool our homes.”
steveta_uk says:
October 23, 2010 at 9:51 am
“Perhaps I’m missing something, but I’ve often wondered what is the point of error bands if everyone ignores them and assumes the ‘mean’ of ‘median’ or some other value is the ‘correct’ one.
Since the IPCC are correct (i.e. the real data is within the error bands) then the theory is OK – perhaps someone needs to work one reducing the error bands.”
I guess we don’t use swamp coolers to heat our homes because we could never figure out in advance whether they would be heating or cooling today.

Ken G
October 23, 2010 10:59 am

You use the same approach, over the same time period, as Schwartz did in “Why hasn’t the earth warmed as much as expected” Journal of Climate 2010.
“The current best estimate and uncertainty range of
the earth’s climate sensitivity suggest an equilibrium
increase in the earth’s global mean surface temperature
for forcing by anthropogenic long-lived greenhouse
gases of 2.1 K (range 1.5–3.2 K, roughly 1 standard deviation),
well in excess of the observed increase relative
to preindustrial times, about 0.8 K. The discrepancy is
attributed mainly to uncertainty in climate sensitivity
and/or cooling forcing by anthropogenic aerosols, also
highly uncertain; countervailing natural cooling and
thermal lag in climate response seem to be relatively
Considering there remains to be no hotspot the tropical troposphere, it would seem this is consistent with an IPCC overestimate of climate sensitivity and WV feedback.

October 23, 2010 11:00 am

Over at climate4you.com there is clear evidence that most of the recent warming was caused by a 5% decrease in cloud cover, which caused about 0.35 deg C warming out of the observed 0.4deg warming during the satellite period.
Therefor CO2 caused only 0.05 c warming compared to the estimate of 0.4-0.6
Ie the sensitivity is 10 times to high.
The ERBE results back up the cloud results, shortwave absorption is up, and the planet responds by losing more energy (longwave increased) demonstrating negative feedback.

Jim D
October 23, 2010 11:02 am

Willis says “Where did I say that my numbers did not include aerosols and the rest? Take a look at the SPM? The IPCC forcing figures are from all sources of forcing, not just CO2 …”
My interpretation of the 3 degrees per doubling does not include aerosols, and it can’t because you can’t predict how those will change with CO2. The aerosols are an additional negative effect that prevailed during the 40’s to 70’s as the aerosol haze/cloud area expanded to its current size. Note that the aerosol effect is limited from growing further by its short residence time in the atmosphere, so its growth does not figure into future projections, and should not unless places like Africa industrialize rapidly.

October 23, 2010 11:08 am

Willis – the observed 0.74 C temperature increase is consistent with the IPCC estimate of 1.6 W/m^2 “forcing”, but the confusion arises because of their unusual definition of forcing; I would have preferred a different term, such as “delta forcing”. The 1.6 figure does not refer to a TOA energy imbalance (ignoring feedbacks) but rather to an estimated change in the variables responsible for creating an imbalance since 1750. As noted, these include CO2, aerosols, and solar changes.
If the atmosphere had instantaneously become imbalanced by 1.6 W/m^2 in 1750, and no perturbations had been added since then, but feedbacks had been allowed to proceed, we would now be close to equilibrium, and the equilibrium climate sensitivity estimate of about 1.4 C should be close to realization. In fact, however, much of the imbalancing factors (particularly CO2 increases) have changed mainly in the past half century, and due to the thermal inertia of the climate system (particularly the deep ocean), we are only part way there. In the process, the imbalance has been reduced by the rise in temperature, so that the current estimate of forcing in its more traditional sense has diminished to a currently estimated 0.9 W/m^2. If this were alllowed to come to equilibrium without further perturbations, the 1.4 C figure you cite would be more or less what we should expect on the basis of current climate sensitivity estimates.

Jim D
October 23, 2010 11:21 am

RobJM, a decrease in cloud cover in a time of warming (if true) would just kill the ideas of Spencer and Lindzen who say the opposite should happen to provide a negative feedback. For AGW it would provide an additional positive feedback that they don’t really consider yet.

October 23, 2010 11:23 am

Dave Springer says:
“Most of the world and evidently half the U.S. electorate as well believes the United States is too powerful, too wealthy, too arrogant, and too willing to flex its muscle around the world and they desperately want that to change in a big way. Hobbling the U.S. economy by making it pay dearly for every ton of CO2 emitted while giving “developing” countries a free pass to keep on growing their emissions of CO2, methane, and black carbon without restriction will accomplish their goal.”
The objective of the Copenhagen conference and the up coming Mexican conference is in addition to giving a free pass to the developing countries to pollute is to send billions of tax dollars to corrupt, comically inept, third world governments. The estimate for the current waste for aid dollars is 1 to 10. 10% of each dollar is effectively spent. The remainder goes to middle men, government officials, other non-related projects, and “consultants”.
The Green Parties are the fantasy parties. Money grows on trees. When I traveled through Europe this summer I saw field after field filled with wind turbines, none of which were turning as there was no wind. Practical engineering issues such as what to do with the wind power that is generated when there is no load or load requirements when there is no wind are ignored.
CO2 is beneficial to the biosphere. Plants eat CO2. The planet’s response to a change in forcing is obviously negative not positive. Global warming is beneficial to the biosphere. (70% of the planet is covered by water. Warmer planet more precipitation.)
The biosphere expands into the higher latitude regions when the planet warms (i.e. Most of the warming occurs for high latitude regions. Storms severity is less not more for a warmer planet. Less difference in temperature from high latitude to low latitude regions.)

October 23, 2010 11:33 am

In my earlier comment, I forgot to mention an important factor that will significantly influence future temperature increases. The 1.6 W/m^2 IPCC estimate balances GHG forcings with the negative forcings due to aerosols. However, aerosol forcing is not increasing, and with pollution remediation measures, may actually be diminishing in much of the world. Therefore, as CO2 concentrations rise, the ratio between CO2 and aerosols will also rise. As a result, one can’t extrapolate to the future from current CO2/aerosol balances, but must include the increasing level of “unmasking” of CO2 effects as a result of the changing ratio.

October 23, 2010 11:39 am

Willis Eschenbach: You’ve been sifting through the IPCC positions for a while. Can you recommend a decent layman’s overview of it all?
I’m looking for something reasonably honest and impartial.

October 23, 2010 12:04 pm

Roger Knights says: October 23, 2010 at 4:40 am

Didn’t Monckton make a similar (or identical) criticism?

(John Kehr also take note) Yes I think so. It was what really clinched AGW as conscious BS for me, when Schmidt claimed to refute Monkton and Monbiot piously quoted Schmidt, but Monckton really wiped the carpet with Schmidt and Monbiot, to which Schmidt replied with a deafeningly loud silence – but still continued carping over Monckton’s original article.

October 23, 2010 12:07 pm

@ Peter D. Tillman
No extra-heat in the pipeline …

October 23, 2010 12:45 pm

Willis, option 8 does provide a solution to this conundrum.
The actual increase in temperature is 1.4C, but its the data that’s wrong. Our modern temperature records are accurate, but the older ones overestimated the temperature. This can be corrected by lowering the earlier records to bring them into line. Some of this correction has already been done to achieve the apparent 0.7C increase, and I’m sure that NASA and HADCrut will be able to find more records that can be adjusted to suit.

Eric (skeptic)
October 23, 2010 12:50 pm

Fred Moolten (echoing prior claims) says “…and due to the thermal inertia of the climate system (particularly the deep ocean), we are only part way there”
Fred, or anybody else, please post some numbers. How much heat is being stored in the ocean, i.e. tell us what the mass is and what the rate of warming is. Please show how you arrived at the rate of warming (real world measurements? Working backwards from missing heat?) Next, please show the rate at which the heat is sent to the deep ocean by showing what the water flow is from the warm surface to the depths and the consequent energy transfer. Then show how that arrives at the measured rate of deep ocean warming.
JJB MKI, I think your explanation is the best one so far.

October 23, 2010 1:01 pm

Please go ask Lucia for her lumped parameter model which I named “lumpy”
You’ll see all the things you left out.

October 23, 2010 1:06 pm

Thanks again, Willis, for another interesting and useful post which gets to the core of how the IPCC cabal of climate scientists clearly haven’t a clue about what really drives Earth’s climate. They seem unable to back off from the ridiculous CAGW conjecture in the face of a mountain of contrary evidence – perhaps too much political pressure and vested interest.
My view is that your arithmetic is correct, and reason 6 gets close to explaining the issue:-
“6. Climate may not obey a linear relationship between forcing and temperature change. My calculations are based on the IPCC assumption that a change in temperature can be calculated as a constant called “climate sensitivity” times the change in forcing. However, climate sensitivity may not be (and in my view is not) a constant. Instead, in my view climate sensitivity is a function of T, which changes the equation.”
First, I think average global temperature is a very poor indicator of our planets energy flows. The amount of energy in the system varies every second of the day and is the driver of all the varying phenomenon we call weather. We do not have the capability to measure the ever changing Earth system energy level and I suspect the estimates we currently use are far off the mark.
The system acts like a complex driven oscillator and non-linear deterministic chaos determines the outcomes we observe at all time scales. Sometimes there is apparent order when linear behaviour occurs, but turbulence and non-linear behaviour can happen at any time, causing the apparent linearity to break down. Turbulence increases when extra energy is in the system, and this in turn increases our planets ability to cool because of maximum entropy production. The system tends to undershoot and overshoot when changing between laminar and turbulent flow.
Long-term weather/climate is made up of many overlapping short-medium-long term quasi-cycles, most of which follow a sinusoidal oscillating curve. This makes any detailed predictions about long-term weather regime/climate impossible to achieve. However, a broad based forecast is possible as shown below:-
1410-1500 cold – Low Solar Activity(LSA?)-(Sporer minimum)
1510-1600 warm – High Solar Activity(HSA?)
1610-1700 cold – (LSA) (Maunder minimum)
1710-1800 warm – (HSA)
1810-1900 cold – (LSA) (Dalton minimum)
1910-2000 warm – (HSA)
2010-2100 (cold???) – (LSA???)

October 23, 2010 1:29 pm

Eric – One good source is the paper by Levitus et al at Ocean Heat Content
The combined effects of aerosols and ocean heat storage can account for the current temperature increases based on the range of climate sensitivities that are typically estimated.

October 23, 2010 4:27 pm

Nullius in Verba says: “…The problem with high sensitivities is that we’ve already seen half a doubling (logarithmically speaking), so we ought to be seeing half the predicted warming. Clearly we’re not. So to explain that, they have invented lags and time delays that shift the consequences decades into the future…”
I’ve suspected for a long time that they’re making this stuff up as they go.

Jim D
October 23, 2010 4:38 pm

Willis, OK, looking at the SPM, remarkably the total anthropogenic forcing is very much like the CO2-alone forcing, but with a wider error bar due to the wide error bars for aerosol effects. It appears the true aerosol effect must have been in the upper part of its error bar range, but you see the error bars surround the observed trend, so is there really a problem?

Carl Chapman
October 23, 2010 10:14 pm

The feedback has to be negative or temperatures would have shot off to the limit millions of years ago.
My guess is a feedback of -2/3. An initial rise in temp of 1.2 for doubling CO2 would cause negative feedback of 2/3 of that, leaving 1/3 of 1.2 = 0.4.
That’s insignificant, so the warming we’ve seen would be due to normal natural changes. I think it was mostly an increase in the solar wind due to a more active sun causing more cosmic rays to reach the earth, causing changes in cloud cover.
A less active Sun, as it is now, should resolve that over the next decade.
By the way, I cancelled my subscription to Scientific American a year ago. They sent me a letter inviting me to re-subscribe. I sent it back saying they could mail me when they decided to live up to the Scientific part of their name. One small half-hearted article isn’t enough.

October 24, 2010 7:01 am

The really fundamental puzzle which I have is this: as far as I can ascertain, NONE of the ‘warmists’ and the world’s Lemming-like politicians seem to have read Kyoto.
The Kyoto protocol talks about reducing CO2 EQUIVALENT – not CO2 itself..! As we all know (or the contributors on this side of the fence at least know) that – for a start- water vapour is a far more potent greenhouse gas than CO2. However – many so-called ‘green’ projects talk about ‘only’ producing ‘harmless water vapour’..!
Oh, really..?
Its all down to the mantra that CO2 is nasty black stuff that chokes children and bunnies – not that it is an essential feedstock for plants, and that the atmospheric concentration of CO2 has been FAR higher in history than it is today.

October 24, 2010 10:09 am

I still can not recognize any anthropogenic forcing in the Greenland record. For most of the time it was warmer.

Doug Proctor
October 24, 2010 10:23 am

How bizarre it is after so many years that there is so much confusion about so few numbers at the base of so large an important issue.
The science is settled. There is consensus. 95% certainty.
Of course things don’t add up, make sense, bring us clarity of vision. The asylum is being run by the inmates.

Steve Case
October 24, 2010 11:03 am

I just got done doing a similar comparison. Chapter 8 in the AR4 quotes Dr. Hansen saying without feedbacks the sensitivity is 1.2°C but he adds the feedbacks from clouds and it increases to 3.2° ± 0.7°C. Here’s a graphic I put together showing that the 280 – 380 ppm increase last century falls in line with the 1.2° value but the 3.2° ± 0.7° overshoots the mark by a wide margin.

Steve Case
October 24, 2010 11:07 am

On further reflection, I find it hard to believe that this hasn’t been done before.
Probably has.

October 24, 2010 3:46 pm

Jim D says:
October 23, 2010 at 11:21 am
RobJM, a decrease in cloud cover in a time of warming (if true) would just kill the ideas of Spencer and Lindzen who say the opposite should happen to provide a negative feedback. For AGW it would provide an additional positive feedback that they don’t really consider yet.
Well, the “opposite” does happen daily in the Tropics as Willis so elegantly described a while back, of course coupled with the condensation of cloud water vapor into rain with the resultant loss of much heat to space every 24 hr. – a mechanism which also supplies a ready explanation for why water vapor has apparently never caused a runaway heating event all by itself, and why CO2 is not going to be able to cause water vapor to do anything more than it has always done.

October 24, 2010 9:29 pm

Gavin Schmidt cannot use + 1.2C climate sensitivity as that would not explain ice ages, hot house climate etc. in his models, therefore he goes for +3 C sensitivity.
See http://www.realclimate.org/?comments_popup=5246#comment-189066

Norm in Calgary
October 24, 2010 10:29 pm

Yabut, are you using homogenized data?

October 26, 2010 6:17 am

A lot of people are confusing the “missing heat”. It is a missing heat _flow_, not absolute over the entire 20th century. It started relatively recently, so is less than half of total heat (although it is significant! And if it is going into the oceans, all it means is that we’re slowing the eventual warming)
If you divide 0.7 C by the forcing range, you get somewhere between 0.3-1.2 K W^-1 m^2 with a best estimate of 0.4 K W^-1 m^2. Significantly lower than the IPCC estimate for _equilibrium_ climate sensitivity, but there are easy ways to explain that.
First off, this isn’t very close to equilibrium temperature change (you can tell that because satellites measure a heating imbalance): so more heating is coming. Second off, there are further uncertainties with natural internal forcings.
A good way of testing the actual value is to run the models that result in the 3 C best estimate for sensitivity. So far temperatures are changing within their expectations: we can’t dismiss them. Similar calculations of feedbacks from modern observations (e.g. ERBE) and calculations of climate sensitivity from the past (e.g. Knutti & Hegerl, 2008) also support the rough 3 C figure.

October 26, 2010 7:56 pm

MarkR, there are countless studies that say the same thing they say. It doesn’t change the fact that if the ENSO adjusted trend line which was 0.00C +/- 0.05C from 1999 – 2008 does not show warming by 2013 then the models will have been invalidated at the 95%. With the oceans cooling or at least not warming this seems possible if not probable. Should some small warming occur to prevent the statistical falsification of the models exactly how much confidence should we have in projections with large margins of error that barely manage to avoid falsification? If a lower climate sensitvity is better supported by the data then a higher sensitvity then shouldn’t the sensitivity with the appropriate margins of error be adjusted to the empirical data? Historical rates of warming support a lower sensitivity. Tropospheric warming to surface warming ratios support a lower sensitivity. Ocean heat content rate of change supports a lower sensitivity. What empirical evidence supports the sensitivities claimed by the models? That they can reproduce the past? When the answer is known? And that they can do this with widely differing parameters? That makes me quite comfortable with the science (cough). How about you?

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