A Strange Problem with the IPCC Numbers

Guest Post by Willis Eschenbach

ABSTRACT

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

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.

baffled24

I think that; “5- I’ve made a foolish mathematical mistake”, fits the bill.
http://www.metoffice.gov.uk/climatechange/science/explained/explained5.html

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!
Tim

John Marshall

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.

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

Josh Grella

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

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

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

Orkneygal

Does this mean that its worse than we thought?

Luis Dias

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

Espen

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

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.

Solaris

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

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

baffled24 – I fail to see the significance of your link!
Willis
‘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

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.

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

Dave Springer

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.
@willis
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

Willis:
You are not using the correct “Math”!
Your math: 2+2=4!
3+3=6!
Climate Math: 2+2=6!
3+3=16!
There is an “Esoteric” formula for that and your not being among the enlightened is why you got it wrong!
😉

Niels A Nielsen

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.

LearDog

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.

anopheles

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

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.

Pascvaks

Willis
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

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

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.

netdr2

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

Willis,
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.
Facts:
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.

Enduser

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?”
http://www.scientificamerican.com/blog/post.cfm?id=asian-coral-die-off-could-be-worst-2010-10-22

trbixler

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

Charlie A

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

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.
http://img638.imageshack.us/img638/8098/trenberthnetradiation.jpg
+ 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.

JJB MKI

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

1DandyTroll

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

Fred

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.

alistairmcd

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

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

cementafriend

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!

Dusty

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

Noblesse Oblige

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

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

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.

higley7

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

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.

david

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?

Bdaman

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

sabril

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

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

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

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