verytallguy,
I’d just note that a large and global MWP if proven implies a high TCR
Isn’t that a circular argument? it seems you are assuming the cause of the MWP was CO2? Why couldn’t it have been caused by interactions of one or more the very large number of factors that cause the abrupt climate changes that happen periodically and also irregularly?
Peter,
it is certain that essentially all the CO2 rise post industrialisation is anthropogenic.
I’m not at all interested in debating that point, it’s simply proven.
On MWP and sensitivity no it’s not a circular argument. I’ll try and illustrate with an example.
Let’s say there was a global and large MWP, and it was caused by solar changes (neither is likely true, but let’s just take it as an example)
We can then estimate sensitivity to the forcing from the change in temperature during the MWP.
The larger the MWP temperature rise in this scenario, the larger the TCR, and the same feedbacks both positive and negative will operate for solar and CO2 forcing.
If there is a strong negative feedback in the climate system, be it clouds, lapse rate, etc it would preclude large temperature variations in global temperature caused by a perturbation in climate, regardless of the cause of the perturbation
VTG,
You lost me at the start of your last comment.
it is certain that essentially all the CO2 rise post industrialisation is anthropogenic.
I’m not at all interested in debating that point, it’s simply proven.
That sort of answer won’t get anywhere. Remember you are trying to explain in simple terms to a policy analyst, politician or intelligent, interested, unbiased non specialist member of the public.
You say it is a fact. If that’s so what’s the evidence?
And how do you explain the increases in CO2 concentration that occurred during periods of warming before the industrial era?
You need to be able to provide simple clear answers to all these sorts of questions.
Peter,
You need to be able to provide simple clear answers to all these sorts of questions.
I don’t *need* to do anything Peter, I very politely gave you a rationale for attribution of temperature rise, which is the topic.
The recent CO2 rise being anthropogenic is as certain as the earth orbiting the sun and the evolution of species.
I have no more intention of debating that than debating the laws of thermodynamics.
I’m happy to debate attribution, sensitivity and other things which are difficult or uncertain.
Feel free to explore or question what I’ve suggested on those, and feel free to research or debate elsewhere the anthropogenic nature of the Co2 rise.
The surface temperature record shows a decadal peak in 1944, a decadal low in 1976 and again a high point in 1998. The cooling from 1944 to 1950 is all ENSO – and this is a substantial part of the warming cited.
The difference between 1950 and 1998 is 0.71K – the difference between 1944 and 1998 is 0.39K.
If it assumed that natural decadal cooling between 1944 and 1976 was exactly balanced by natural decadal warming between 1976 and 1998 – the residual due to anthropogenic effects was 0.39K.
Was the residual all anthropogenic? Models give us no clue at all – there are literally thousands of plausible solutions to any model and tuning gives no reassurance that the complex physics of climate are captured. Paleodata is simply playing games – we barely have enough data in recent decades to constrain estimates. Energy budgets are a joke unless you know what is actually happening with TOA energy flux and why.
‘In summary, although there is independent evidence for decadal changes in TOA radiative fluxes over the last two decades, the evidence is equivocal. Changes in the planetary and tropical TOA radiative fluxes are consistent with independent global ocean heat-storage data, and are expected to be dominated by changes in cloud radiative forcing. To the extent that they are real, they may simply reflect natural low-frequency variability of the climate system.’ AR4 3.4.4.1
Independent evidence from multiple sources suggest – if ‘real’ – that recent warming was all cloud changes associated with decadal changes in ocean and atmospheric circulation.
What seems incontrovertible is a prospective downturn in solar activity from the late 20th peak – and a decrease in El Nino frequency and intensity from a 1000 year high.
VTG,
I don’t *need* to do anything Peter, I very politely gave you a rationale for attribution of temperature rise, which is the topic.
The recent CO2 rise being anthropogenic is as certain as the earth orbiting the sun and the evolution of species.
OK. So clearly you are simply a Climate Cultist. You have beliefs and if challenged to explain why you believe, you fly into an uppity defence of your cult’s beliefs.
Your response is another example of how the Climate Cultists carry on. You would have done better for your cause to have not answered, because what you’ve done is reinforce for me that those of your persuasion are just cultists. Referencing SkepticalScience and RC damaged your credibility from the time you told me to go read the answers to my questions on those sites. Do you have any idea of who set up and paid for RC and do you know about what Skeptical Science has been up to. If you don’t know, go find out.
What the hell are you talking about? You don’t make an ounce of sense.
It is perfectly simple. Simple enough even for your brain to take in surely.
The IPCC and you, have stated that the expected median increase from doubling CO2 would be 3.25c .We are about half way there, so according to you we ALREADY have increased temperatures by about 1.6c. ACTUAL temperatures are influenced by the underlying ‘natural trend overlaying that apparent inescapable increase.
Therefore according to you and your IPCC chums, current temperatures would be 1.6c cooler that today’s measured temperatures if Man had not emitted any CO2 at all. Don’t have to be Einstein to figure that out now do we?
That would be cooler than the Little Ice Age and as the measured warming trend decreases you must believe that this long term cooling trend is getting worse. i.e.when CO2 reaches 560ppm you must believe that, whatever the actual temperature is at that time, it is 3.25c higher than it otherwise would be naturally.
So answer the question do you believe the Earth should naturally be currently colder than the LIA and cooling further as we speak?
Alan.
… How do you use this idiom to make the comparison then? …
Easy – you say that “more than all of the temp rise that didn’t happen during the last 15 years is due to anthropogenic causes.
Peter,
compare and contrast
you originally:
Is anyone who blogs on CE capable of meeting my request (while refraining from the usual abuse and snide remarks)?
you now:
OK. So clearly you are simply a Climate Cultist. You have beliefs and if challenged to explain why you believe, you fly into an uppity defence of your cult’s beliefs.
You asked for clear and simple attribution without abuse and snide, which I provided, using data directly from the host’s papers.
You choose to challenge realted but separate unequivocal and well understood science, and tell me I *need* to go down that rabbit hole.
Now you come back with snide and abuse.
I am not your encyclopaedia. There is a level of accepted science below which there is no point in debate. Co2’s anthropogenic origin, for me is one of these. I have no problem if you want to challenge that, but equally I have no intention of wasting my time on it.
If a company grossing $10,000 makes $2 net profit, and I made $3 for it, am I responsible for 150% of the company’s profit?
Interesting. Thanks.
Thank You for explaining this to me Judith.
I see it now! It’s brilliant. The circle is closed. All bases are covered.
Warming is what they say it is – no matter what happens.
Can’t wait to see the fingerprints on the models!
Two and two are five! Sometimes they are three. Sometimes they are all of them at once. I must try harder. It is not easy to become sane!
(apologies to Orwell)
yes. I’m aware of that. Perhaps you should first analyse your own responses. As far as I am concerned, you are not someone with credibility.
Show me a reference stating you can just ignore GIA for short term changes.
VTG,
You didn’t answer the question. You weren’t capable of answering the question. You should have shut up and let others answer.
I never said it was an error in GRACE data. I specifically said the isostatic rebound models were questionable.
I think I may have written about this in the past, but here it goes:
In the oil industry we run computer models which use hundreds of thousands and sometimes above one million cells. The models are used to match the data, and to run forecasts, which are expected to run for as much as say 50 years (although a 20 year forecast is much more common).
When we run these models we do attribution analysis, but I find such attributions to be somewhat inaccurate. And some of them are absolute non sense, because the different “forcings” are interrelated. This means that in each time step a “forcing” can impact how other “forcings” behave. Imagine the frustration we suffer when management insists we try to separate the individual effects so they can decide if they were worth the effort.
In our case a “forcing” can be the injection of CO2 slugs. These are injected using wells, and are alternated with water injection. Imagine the mess when we are asked to figure out whether an individual well in a 20 well pattern is worth drilling and used to inject. However, that’s the type of question I have faced in the past.
Steve Ta, according to the logic of Judith Curry’s critics, yes!
+1
I think this underlines the sophistry employed by the IPCC and others when attempting to convince policy makers of how ‘significant’ the contribution from anthropogenic greenhouse gases has been with regard to the very moderate warming we have seen since 1951. Their measure of ‘significance’ is phrased in an obscure and impenetrable manner that is far removed from what most people would understand to be logical and consistent with reality. Fraction of Attributable Risk (FAR) models are increasingly used nowadays to ‘fingerprint’ regional and global climate variability and even extreme weather events. As Judith says, those ‘fingerprints’ look very ‘muddy’
I think a comment I made recently on another blog is apt to repost here:
“If I understand TCR (to doubling of CO2) correctly, it involves only the positive radiative forcing theoretically calculated from the increase in atmospheric CO2 plus an array of positive and negative feedbacks which are a direct consequence of the increase in CO2 radiative forcing. I am guessing that this would include increases in other associated GHGs (+ve feedback) and increases in aerosols from fuel burning (-ve feedback). Though natural variability (external and internally generated – including the cooling effect of naturally produced aerosols) would affect the final temperature achieved, this would not affect the calculation of TCR as long as natural variability is accounted for. So solar, volcanic activity, ENSO/AMO etc. are independent of TCR and any measurement of TCR would presumably have accounted for their (presumed estimated) effect upon global temperatures.
The situation we have here is that the cooling effect of man-made aerosols has declined appreciably [since 1951] as CO2 emissions and other GHGs have increased, so we would expect even greater warming, which hasn’t happened. Hence TCR must be lower than previously thought. Of course, it could be argued that natural variability since 1951 has been appreciably greater than that which is estimated by the IPCC, and that this may explain part or all of the observed reluctance of temperatures to rise as quickly as they have been predicted to rise using AGW forced models. In which case a higher estimate of TCR could be argued. But this requires natural variability to have contributed a net negative influence on global temperatures over that period. If it has been net positive – which looks more likely – and greater in magnitude than assumed by the IPCC in their calculations, this will put even more pressure on the downward revision of TCR.”
The IPCC refuse to consider the real possibility that the majority of the positive climate forcing (I deliberately do not use ‘warming’ to avoid confusion) we have seen post 1951 may be due to internal and even external variability. As there is very little room to include any negative contribution from man-made aerosols, this necessarily implies that the positive climate forcing contribution from anthro GHGs has been minimal, which brings into question the ‘urgency’ of climate mitigation measures.
