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« New Zealand's temperature record | Main | Snail's pace - Josh 298 »

McLean on clouds

John McLean, of James Cook University in Australia, emails with details of a paper he has just had published in Atmospheric and Climate Sciences about the warming of the planet at the end of the last century. He adds a useful layman's summary.

The paper ...

- indicates that the temperature pattern can be attributed to a sequence of events, namely a shift in the prevailing ENSO conditions, then a reduction in total cloud cover and then a shift on cloud (decrease in low level cloud that was largely offset by an increase in mid and upper level cloud)

- uses the Trenberth, Fasulo & Kiehl energy balance diagram to show that the loss in total cloud cover caused an increase in heat energy being absorbed at the Earth's surface that was greater than the increase that IPCC 5AR claims was due to greenhouse gases

- indicates that greenhouse gases played little if any part in the warming, which not only refutes the IPCC's belief or opinion but also means that there is negligible, or even no, 16 or more years' of "missing heat" to be found.

- shows the changes in cloud cover and temperature both as global averages and then for the six latitude bands each of 30 degrees, the latter indicating the changes in cloud cover applied to most latitude bands except the Antarctic and to a less extent 30S-60S.

- doesn't attempt to identify the reason for the reduction in total cloud cover or the shift from low level cloud.

The paper is open access and can be seen here.

Update 7.52am, 31.10.2014 John McLean commented  at 9.20pm last night that he is a PhD student, not a professor. TM

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Reader Comments (59)

So, the missing heat has been found... beyond Alpha Centauri :-)

Oct 30, 2014 at 9:48 AM | Unregistered CommenterDave Salt

Wonder how they missed this paper, prime candidate for PALS review torture ;)

Oct 30, 2014 at 9:53 AM | Registered CommenterBreath of Fresh Air

Will Prof. McLean suffer the same fate as Prof. Bob Carter ? James Cook Uni., Townsville has not been kind to people who question CAGW.
Emeritus Prof. John Nicol, also from JCU, wrote a detailed critique of so called 'back radiation' from CO2.

Oct 30, 2014 at 10:15 AM | Unregistered CommenterG. Watkins

Interesting that he's a real physicist. :-)

Oct 30, 2014 at 10:41 AM | Unregistered CommenterNial

Obviously any fairly small change in the amount cloud cover would have a big effect on energy balance. I've read a few summaries stating late 20th century cloud cover was low, is that true?

Oct 30, 2014 at 10:54 AM | Unregistered CommenterRob Burton

I see no reason why this paper should be controversial.

If you remember Sherwood et al 2013 , they noted that models with an increasing proportion of high cloud gave more realistic projections.

McLean has noted a similar change in cloud cover and a similar result.

He does seem to have oversimplified the cause and effect relationship. Most involved view the change in cloud cover and its warming effect as a positive feedback effect of warming, rather than as its cause.

Oct 30, 2014 at 10:58 AM | Unregistered CommenterEntropic man

"the change in cloud cover and its warming effect as a positive feedback effect of warming"

Well, that's interesting - warming causes warming. Or should it be that warming causes warming. You choose.

Oct 30, 2014 at 11:05 AM | Unregistered CommenterBudgie


Most involved view the change in cloud cover and its warming effect as a positive feedback effect of warming, rather than as its cause.

Those would be the same scientists who predicted The Pause ahead of time I'm sure.

Oct 30, 2014 at 11:05 AM | Registered CommenterRichard Drake

Your Grace
Is this not the same argument that Dr Roy Spencer has been making for some time.I understand that he says cloud effects are usually treated as a feedback to CO2 warming but cloud levels can change for other reasons and in effect become the forcing.He wrote a book on the matter.

Oct 30, 2014 at 11:21 AM | Unregistered Commenterroger

Well the IPCC-stated argument that the late 20th century warming must be CO2 because they can't think of anything else, which was always a logical fallacy anyway, has to perhaps now consider a 'something else'. However I expect it will simply be ignored on the basis that there is no explanation of why cloud cover changed. It is perfectly possible for the climate clique to argue that manmade CO2 could have caused the warming that caused the cloud feedback that causes more warming. Even though the relationship is reversed from their usual more clouds=more warming mantra such U-turns are quite common in climate science and justified by 'initial uncertainty'. Of course it is well-established that some clouds cause warming and others cause cooling so all arguments are acceptable as long as CO2 is the cause one way or the other. If they can argue global warming causes Antarctic cooling then clearly no causation logic is off limits.

Oct 30, 2014 at 11:47 AM | Unregistered CommenterJamesG

About a year ago Euan Mearns and myself submitted an almost identical paper to Climate Dynamics. It was eventually rejected by just one of the referees, partly because they did not like the conclusion.

I wrote a post based on that paper which can seen here

We used a combined Cloud Forcing and CO2 forcing model to compare to Hadcrut4 temperature data. We found that about half of the observed warming from 1983 to 2000 could be explained by a decrease in global cloud cover, and that the hiatus in warming could be explained by a slight increase in GCC since then.

By then fitting the model to the observations we measured TCR = 1.4 ± 0.3 C

Oct 30, 2014 at 11:56 AM | Unregistered CommenterClive Best

Back to Trenberth, and demonstrating I'm sure my woeful ignorance, but am always willing to be corrected, if you can, friend or foe, please do.

From memory Trenberth assumes 77w/m^2 of heat reflected by clouds and finishes with an energy imbalance of 0.9W/m^2. So a variation in cloud cover causing an increase in reflected heat of 1W/m^2 would negate the imbalance. In other words if the reflected heat from clouds from 77W/m^2 to 78W/m^2 gives a balanced radiation budget.

In other words clouds have to maintain exactly the same radiative reflectivity for a year for the budget to be proven and must not increase radiative reflection by 1.3% average over that period. Am I alone in believing that cloud cover is much more volatile than 1.3% up or down? If I am please point me to the literature. It all looks terribly flaky to me, but ignorance has never stopped me asking questions.

Oct 30, 2014 at 12:00 PM | Unregistered Commentergeronimo

"...there is no explanation of why cloud cover changed."

Long term ocean circulation, Svensmark effect, just some internal variability, easy to come up with some possible reasons. Clouds fundamentally cool as they stop the sun's rays reaching the ground in the first place. Just because a cloudy night might keep things warm for a while is a odd definition of 'warming' to me.

Oct 30, 2014 at 12:10 PM | Unregistered CommenterRob Burton

UK temperatures since 1956 - physical models and interpretation of temperature change

Together with Clive Best, we also did similar analysis of UK temperature variance in relation to cloud cover. Sent it to Nature twice and one other journal with no luck.

In this post we present evidence that suggests 88% of temperature variance and one-third of net warming observed in the UK since 1956 can be explained by cyclical change in UK cloud cover. The post is co-authored by Clive Best and builds on an earlier post that described the UK Met Office climate station data from 1933 to present (links given below).

Oct 30, 2014 at 12:10 PM | Registered CommenterEuan Mearns

I presume this is the same John McLean whose work the players at SkS sought to discredit during 2010-2012. If so, all the more kudos to him.

This is exactly the sort of work that may have been discouraged by the headlong rush to demonise CO2 by the malevolent schemers behind the IPCC. It is complementary to Hubert Lamb's wish that past climates be studied to help establish 'natural variation' before taking conjectures about recent changes too seriously. The examination of other sources of variation in modern climate history helps that same end. This is why this new paper by McLean is very welcome, and I look forward to studying it soon.

In the meantime, I note another Australian, a statistician called Jonathan Lowe, reported a few years ago his statistical analysis which adjusted temperature records by 'taking out' variation which he was able to associated with variation in cloud cover. His results suggested about half of observed temperature rises in Australia could be due to variation in cloud cover. This was a piece of informal publishing on his blog, and I do not know if he has developed it since into a published paper.

Oct 30, 2014 at 12:11 PM | Registered CommenterJohn Shade

Greetings from Oz. Geronimo, if I remember correctly, the uncertainties of each of the components of the "energy balance" estimate to which you refer are many times the supposed imbalance of 0.9 w, so worrying about this is simply a waste of time. Have a nice glass of red wine with dinner and enjoy life!

Oct 30, 2014 at 12:16 PM | Unregistered CommenterBoyFromTottenham

Clive and Euan, I suspect that if you had sent your paper to Atmospheric and Climate Sciences (and paid the $800 article processing charge), your paper might well have been accepted.

Oct 30, 2014 at 12:36 PM | Registered CommenterPaul Matthews

What Paul Matthews said.

Oct 30, 2014 at 12:40 PM | Registered CommenterJonathan Jones


That's why it is almost impossible to get anything published without the financial backing of a university or of a government funded research programme.

We are left with blogs !

Oct 30, 2014 at 12:44 PM | Unregistered CommenterClive Best

@ Clive B & Euan M

In the light of Professor McLean's paper, are you able to resubmit, ask for Climate Dynamics' rebuttal of JM's paper?

Oct 30, 2014 at 12:58 PM | Unregistered CommenterJoe Public

"doesn't attempt to identify the reason for the reduction in total cloud cover or the shift from low level cloud"

I'm sure the climate scietivists are already inventing reasons why this is directly attributable to CO2 levels, consistent with their models and even worse than they thought.

Oct 30, 2014 at 1:15 PM | Unregistered Commenterjaffa

@ Paul

(and paid the $800 article processing charge)

Wot, and blow a whole days donations in one go?! ;-)

@ Joe

If we were fully paid up academics then we would persevere cos our careers would depend on it and we would be getting paid. But as unsalaried bloggers the whole peer review process is just too time consuming. Nature rejected both papers within hours - never read them. Probably compared the conclusions with the script, got a mis match, and responded accordingly.

Oct 30, 2014 at 1:38 PM | Registered CommenterEuan Mearns

I am glad to see clouds getting some attention. I think Judith Curry has promised a blog on clouds.

One thing that has always puzzled me is the claim that high cloud leads to warming - I guess this means higher lows rather than higher highs and if that is the case it seems to me the sort of warming that pretty much all of mankind would welcome.

I also seem to recall that Roy Spencer says that one of the big problems is that it is impossible to say what is cause and what is effect - is cloud a forcing or a feedback. One suspects that it must be both but impossible to tell when it switches from one to the other.

H2O in its most miraculous guise!

Oct 30, 2014 at 2:15 PM | Unregistered CommenterH2O: the miracle molecule

Blue Sky Thinking data needed

I'm having a very similar problem with cloud cover and it is this.

There has been a discussion amongst some archaeologists and to help move the discussion forward I am looking for information on the probability of seeing a sunrise at Stonehenge - ideally in the Neolithic but I will settle on today. indeed, I will settle on anywhere S-central England.

I am having a terrible time trying to find anything. I can't even find out how much more/less likely it is to view the midday sun compared to that closer to the horizon.

I've even been looking today at buying some meteorological equipment at $1000 but unfortunately that is well outside my pay bracket.

If anyone (e.g. John McLean) happens to read this and happens to know where I can get solar data and/or cloud cover data, by which to work out a suitable figure I would appreciate it. (Ideally the solar and/or UV level at regular intervals through the day with information on the local horizon)

For info on discussion see: The probability of seeing a sunset

Oct 30, 2014 at 2:32 PM | Registered CommenterMikeHaseler

To John McLean ... regarding figure 1, this shows a remarkable correspondence in date with my own post Cosmic rays & the late 20th century temperature data: a smoking gun?

I've got a small collection of similarly timed divergences so perhaps these might be of interest.

The question I raised in that post was could this divergence be due in some way to the cleaning up of the atmosphere after the 1970s clean air acts?

Oct 30, 2014 at 2:49 PM | Registered CommenterMikeHaseler


Not sure there has been much cleaning up of the atmosphere outside western Europe and North America!

Oct 30, 2014 at 3:04 PM | Unregistered CommenterGlebekinvara

Glebekinvara, I was looking at an old photo of a railway engine trying to work out its location. Eventually I realised it was Dundee - apparently in the fog - until I realised that all the landscape photos I saw in the 1800s had this dense fog ... or smoke.

In the 1970s most of the world was not industrialised., but the level of pollution was high. Then from 1970s onward we saw a massive clean up. E.g. rivers started to become suitable for fish and the air was breathable.

From the 1970s -- this increase in solar as a result of less smog would have led to world wide increase (or more accurately recovery) of temperatures.

Then around 2000 we began to see heavy industrialisation in the former "2nd world" countries. ... and since then we've had this unexplained "pause".

As the CERN project showed, even very small traces of some chemicals can affect cloud cover. Therefore it is at least plausible that much of the warming was due to reduction in pollution levels from the 1970s-2000.

Oct 30, 2014 at 3:23 PM | Registered CommenterMikeHaseler

I also seem to recall that Roy Spencer says that one of the big problems is that it is impossible to say what is cause and what is effect - is cloud a forcing or a feedback. One suspects that it must be both but impossible to tell when it switches from one to the other.
Oct 30, 2014 at 2:15 PM | Unregistered CommenterH2O: the miracle molecule

Yes. That is what Entropic Man appears to miss, upthread.

Unlike cloud cover and temperature, feedback cannot be measured. Positive or negative, it must be inferred. And, judging by the data, IPCC proponents have inferred wrong.

Water vapour and its cloud effects is the dog that IPCC modelers claim is being wagged by the tail of CO2 in their models. They acknowledge that it is probably the most important effect.

They acknowledge that they can't do it: Theory lacking. Not enough data to make it. Not enough CPU time to fake it.

Oct 30, 2014 at 3:25 PM | Unregistered Commentermichael hart

McLean over-simplifies. One can't talk about the effect of clouds without considering their altitude!. All clouds reflect incoming SWR and absorb outgoing OLR. However, the amount of radiation they emit depends on their temperature and therefore their altitude. Raising a cloud top 1 km drops its temperature 6.5 degK and reduces its emission by about 10%. The situation complicated - DLR emitted by the cloud bottom also changes and the intensity of the absorbed OLR varies with altitude. Our observation systems may not have the ability to monitor clouds accurately enough to determine how much radiative forcing changing cloud cover may be causing.

Oct 30, 2014 at 3:50 PM | Unregistered CommenterFrank

Offhand, does anyone know how good the cloud data is? A few years ago when Spencer and Braswell and then Dessler published their papers, it seemed fairly clear that the data was hard to interpret and very uncertain unless it was processed by very re-analysis models. Has the situation changed recently or do uncertainties in the data suggest that McLean's findings are only provisional? I guess Clive and Euan probably have a view on this matter.

Oct 30, 2014 at 3:50 PM | Unregistered Commenterdiogenes


At the time I started looking at the global cloud data I had some correspondence with William Rossow at NASA. My reading of the tea leaves is that NASA send up a satellite to measure clouds, get results that don't fit the script, and so the warming community call into doubt the veracity of the data. Rossow said he had checked and double checked all the algorithms and was fairly damming of the IPCC. Amongst other things NASA provide software to analyse their .csv files that allowed me to make this cool plot.

The work I did on the UK was based on surface sunshine measurements. Sun in line of site with surface sees through all the complexity of cloud layers. Thanks to Clive's physics we made a stab at estimating climate sensitivity using both global and UK cloud variability and got values close to 1.4 ˚C both times.

Oct 30, 2014 at 4:37 PM | Registered CommenterEuan Mearns


Nice graphic! Antartica looks to have possibly the least average cloud cover (most dark blue) - not exactly intuitive, but never been there...

Oct 30, 2014 at 4:47 PM | Unregistered CommenterSensorman

That excellent highlighter of subversive research papers (subversive to the simple but insidious world of the IPCC SPMs for example), the Hockey Schtick blog, is reporting on a related topic:

New paper finds sunshine has controlled maximum temperatures and temperature ranges in China since 1962

A paper published today in the Journal of Geophysical Research Atmospheres finds that daily [diurnal] temperature range in China decreased from 1962 to 2011, and that this decrease was due to a decrease in maximum temperatures related to a decrease of sunshine durations over this period.

These changes are indicative that sunshine durations, rather than increased greenhouse gases, were the "control knob" which decreased maximum temperatures and decreased daily temperature ranges throughout China, and opposite of the predictions of AGW theory and climate models.

'Inch by inch, row by row
We shall see the rascals go'

Oct 30, 2014 at 4:50 PM | Registered CommenterJohn Shade


Most involved view the change in cloud cover and its warming effect as a positive feedback effect of warming, rather than as its cause.


Ah, the mythical positive feedbacks again. Would these be the same positive feedbacks that have enabled the Earth to maintain a stable climate sufficient to sustain life for hundreds of millions of years?

Funny how CAGW starts falling apart as soon as you apply common sense..........

Oct 30, 2014 at 5:07 PM | Unregistered CommenterAnything is possible

@ Sensorman

Vostok is a desert, gets about 1mm snow / year. Looking along these lines of data I see a rhythmical beat. Is it possible for global cloud cover to be constant? The answer has to be no, its impossible. And so the question is how variable and why?

Oct 30, 2014 at 5:11 PM | Registered CommenterEuan Mearns


The longest continuous dataset is from the International Satellite Cloud Cover Program (ISCCP). The data has been criticised for certain viewing biases, although these have consequently mostly been corrected - according to NASA. The real problem is that these data show a slow decline in cloud cover from 1980 to about 2000 which does not fit well with the CO2 being the driver of climate. The IPCC does not consider ISCCP 'reliable' as it does not fit their models.

Any decrease in low clouds leads to a net increase in solar forcing!

The CERES data will be more robust but does not yet cover a sufficient timescale to see trends. IPSC and CERES agree that trends over the hiatus period are flat.

P.S. CERES data is not accurate enough to measure the net Top of the Atmosphere energy imbalance. This is instead normalized to agree with models.

Oct 30, 2014 at 5:40 PM | Unregistered CommenterClive Best

"doesn't attempt to identify the reason for the reduction in total cloud cover or the shift from low level cloud"

Cloud formation is affected by aerosol numbers. Aerosol numbers vary because of... well, why do they vary? Le Quere did a paper on bacteria influencing their environment by producing aerosols. Plankton produce DMS. Breaking waves, smoking power stations, car exhausts and dusty agriculture change the numbers.

We do know all these numbers, don't we? We've allowed for the measured variability of aerosols and incorporated the data in the models?

What has happened to plankton populations? Has the balance between diatoms and calcareous plankton changed? Have farming practices altered nutrient run-off into the oceans, increased/decreased/changed the timing of dust emissions? Has ocean pollution changed salt production, DMS production? Has agriculture altered bacterial aerosol...

You get my point. Have we measured other possible causes of climate change or have we just ignored everything except CO2?

Judith Curry tried to get the aerosols over Deep Water Horizon measured, but the aircraft was busy elsewhere. There are still scientists around,


Oct 30, 2014 at 6:40 PM | Unregistered CommenterJulian Flood

Michael Hart

Water vapour and its cloud effects is the dog that IPCC modelers claim is being wagged by the tail of CO2 in their models. They acknowledge that it is probably the most important effect.

There can be little doubt that H2O the miracle molecule regulates the temperature of the earth (IMHO). As water vapour it is a powerful greenhouse gas but as cloud it provides significant cooling and all in response to changes in temperature.

It does other tricks to move heat from the surface. All in all a wonderful little fellow, though I say so myself.

Oct 30, 2014 at 6:49 PM | Unregistered CommenterH2O: the miracle molecule

H2O the miracle molecule

H2O vapour varies from about zero to 50,000 ppm in the troposphere at any given point in time.

CO2 varies from about 400 to 400 ppm at any point in time but has drifted upwards by about 140 ppm since Watt invented his steam engine.

So go figure which molecule performs miracles ;-) Also take into account that the IR absorption bands for CO2 are already saturated at surface at pre industrial levels.

Oct 30, 2014 at 7:35 PM | Registered CommenterEuan Mearns

I read, many many years ago, a book on megaliths and their use in sighting astronomical events. Having done a google search on The Paps of Jura which is the one that stuck in my mind I came across this.

Ballochroy Standing Stones
Tarbert, Argyll
Stone Row
CANMORE site record

The three stones in this row stand 6, 11 and 12 feet tall.

They line up to the southwest in the direction of the midwinter sunset. Unusually their broad faces lie across the row rather than with the row. Sighting along the broad face of the stones to the northwest you find yourself looking to where the midsummer sun sets behind the Paps of Jura - very distinctly shaped mountains on the Isle of Jura.

Looking back the way, the stones make a line to the northeast that indicates the most northerly point that the moonrise reaches.

At mid summer/winter sunrise/sunset there is about a week where the sun rises and sets in almost the same place on the horizon. This allows for one day's sighting if the weather is bad. The blanket bog started forming about 5000 years ago burying the trees which had died as a result of colder wetter conditions. That, to me, suggests that the last ~5000 years have been cloudier than the previous millennium.

I don't know if that is of any help in what you are looking for.

Oct 30, 2014 at 8:00 PM | Unregistered CommenterSandyS

Julian Flood @ 6.40: "aerosol numbers vary because of - well why do they vary?"

Possibly we might have known but for the failure of the Taurus XL launch to deploy the "Glory" satellite 3.4.2011.
This would have provided exceptional data on Solar Irradiance, aerosols and cloud - the three great unquantified variables of climate theory.
Two years earlier (24.02.2009) the same launcher failed to disgorge the OCO1 satellite providing information on CO2 concentrations, sources and sinks, no doubt providing useful data before the Copenhagen conference.
OCO2 successfully launched 2nd July this year on a different launcher.
Good god - I've created my first conspiracy theory. Good job I still have my granddads old ARP Helmet . Do I need a tinfoil liner?

Oct 30, 2014 at 8:01 PM | Unregistered Commenterdiogenese2

Evan Mearns

I think it's H2O which is the miracle molecule. Can I claim the prize? Mind you, CO2 once used to be great for extinguishing fires.

Oct 30, 2014 at 8:31 PM | Unregistered CommenterMike Post

@SandyS, strangely the discussion started when I tried to explain that it is impractical to calibrate the calendar against the sun when it is as solstice, precisely because it doesn't change position for around a week.

As are result of the discussion I wrote the article: Stonehenge the Calendar in which I explain the best time to calibrate a calendar against the sun is at equinox (Autumn/spring) and that one would expect a series of alignments because the sun is often not visible at sunrise.

The only data I have to support that assertion is that in videos of the last 14 druidic/pagan midsummer festivals, there are only two years when the sunrise is visible. This suggests that only 14% of sunrises are visible, suggesting that it could only be calibrated to a single day's alignment every 7 years. So, one can imagine a neolithic sceptic, asking: "how do you know the calendar is accurate?". So we might expect the monument to start having added alignments to provide more regular calibration if it was used to calibrate a date. However, it is very difficult to see anything resembling this kind of feature - so perhaps this means that they didn't have any concept of date - which then begs the question whether any of the alignments had any functional purpose.

And yes you are right that the climate turned colder-wetter (supposedly??) around or after the time Stonehenge was being built. So, it is quite possible the sun was more visible in the past.

Oct 30, 2014 at 8:33 PM | Registered CommenterMikeHaseler

Slow down! I'm not a professor of physics (yet). I'm a PhD student in that department. I'm not sure where my "professorship" came from. This is how rumours get started ...:-)

Oct 30, 2014 at 9:10 PM | Unregistered CommenterJohn McLean

My sympathies to Clive and Euan for the rejection of their paper along similar lines to mine.

I had a struggle to have this paper published too. First it went to a well-known journal whose editor didn't even send it for review and told me that I had to show why late twentieth century warming could NOT have been caused by CO2. Later, being a paper on clouds and temperature, I submitted it to a journal that deals particualrly with clouds, but the editor rejected it as being unsuitable for the journal.

The publication of a paper doesn't mean that it's "correct" but only that it's made available for wider consideration. Reviewers and editors should only consider whether the hypothesis is well-presented and contains no obvious flaws in logic, mathematics or science, but unfortunately papers can be, and often are, rejected for less objective reasons.

Oct 30, 2014 at 9:36 PM | Unregistered CommenterJohn McLean

@ John McLean: "The publication of a paper doesn't mean that it's "correct" but only that it's made available for wider consideration."

The problem is that the "warmist establishment" are doing, and will do, all they can to prevent the publication of any papers that do not support the 'party line'.

Oct 30, 2014 at 10:41 PM | Registered CommenterSalopian

Oct 30, 2014 at 9:36 PM | Unregistered CommenterJohn McLean

The traditional model of publishing is dead. reading Euan's rejection implied they agreed with him and it just didn't add anything to the subject. How did science reach this state where commonsense became unpublishable,

Oct 30, 2014 at 10:42 PM | Unregistered CommenterRob Burton

@ John McLean

The simple observation for me was that if the sun shone more in the UK it was warmer. I didn't need a new £100 million pound computer to work that out. In fact I think varying cloud cover is one of the only ways to vary ocean heat ± inertial time lags. You are of course correct and wise when you say being published does not make you right. But being published corruptly by the existing peer review system is more likely to make you wrong (I'm not referring to your paper in this instance). If I were the proprietors of Macmillan publishing I'd be incredibly worried. Over $1.7 trillion has been spent on new renewables the last decade or so with the sole purpose of reducing CO2 emissions based on advice from the scientific community. The cost of this to the global economy is multiples of that sum. At some point the chickens will come home to roost.

Good luck with your PhD. A good title might be "Die Hard in Australia" ;-)

Oct 30, 2014 at 11:45 PM | Registered CommenterEuan Mearns

Clove/Euan Thanks for your comments. Are you able to characterise the uncertainty in your findings in any rigorous way?

Oct 31, 2014 at 12:10 AM | Unregistered Commenterdiogenes

Anything is possible

According to the paleo and observed data global temperature has varied through 20C over the last 700 million years, 10C over the last 2 million years, 5C over the last 25000 years and 0.8C since 1880.

Conditions have varied between glaciation to the Equator and ice-free poles, with sea level variations exceeding 120M.

That is not a stable climate.

Oct 31, 2014 at 1:38 AM | Unregistered CommenterEntropic man

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