More excuses for “the pause”.
A team of researchers from the U.K. Met Office, Sweden and Australia has found that three periods of global warming slowdown since 1891 were likely due to natural causes rather than disruptions to the factors causing global warming. In their paper published on the open access site Science Advances, the group describes their study of global mean surface temperatures (GMST) since the late 19th century and what they found.
In this new paper, the researchers looked at GMST as registered by multiple sources around the globe over the past 127 years, noting the slow march of temperature increases. More specifically, they noted the three previously identified slowdowns in GMST increases—the time periods from 1896 to 1910, from 1941 to 1975, and then from 1998 to 2013. They then looked at factors that could have contributed to these slowdowns and found natural causes for each.
The team first reports that their study showed results similar to others regarding GMST increases—they have been slowly increasing overall for more than a century. They then offer possible explanations for the three main observed slowdowns in GMST increase. For the first slowdown, they found evidence of El Niño and La Niña weather patterns that likely reduced heating by producing more cloud cover.
For the second slowdown, they found evidence of increased volcanism—smoke and ashes from volcanoes can block sunlight.
The team asserts that the third slowdown, aka “the pause” which is also the one on which many global warming skeptics like us here at WUWT follow, was likely caused by a combination of La Niña events and volcanism.
They also claim that the third slowdown period wasn’t a stopping point, and they say temperatures continued to rise, they just did so at a slower pace.
They also looked at data from studies of the sun and found that there was a slowdown in energy output from 2001 to 2010, which was also a likely contributor to the third slowdown. In other words, the sun’s TSI does have an effect, and that works both ways. It seems nature is still in control.
They write:
Our main conclusion is that the most robust influence on the 1998–2013 slowdown resulted from the cooling effects of reduced TSI forcing between 2003 and 2011 (Fig. 6B, i) followed by a trend toward increasing La Niña conditions and a negative IPO in its second half. The negative IPO is in turn likely to have been enhanced by regional anthropogenic aerosol forcing (43). Cooling throughout the slowdown was slightly but significantly enhanced by persistent but small increases in volcanic forcing.
Reconstructions for slowdown period 3, 1997–2015 and its three main sub-periods, where the observed time series include the lead-in period 1995–1996. (A) Average reconstruction of GST for slowdown period 3: 1997–2015. The linear trends are for 1998–2013 (thin lines) and 2001–2010 (thick lines). Otherwise as for Fig. 2A. (B) Reconstruction of WMO GST for slowdown period 3: 1997–2015. Otherwise as for Fig. 2B. (C) Linear components of total temperature change over slowdown period 3. (a) 1998–2013; (b) 2001–2010; (c) 2001–2013. Stars denote significance at the 1% level or better. Otherwise as for Fig. 2C. (D) Summary of the contributions of significant forcing (at <1% level) factors to GST trends (°C per decade) during (a) warming periods and (b) slowdown periods. The period 2001–2013 is used to represent slowdown period 3 where the appreciable but not significant ENSO-induced trend is shown.
The paper: (open access) http://advances.sciencemag.org/content/4/6/eaao5297.full
Causes of irregularities in trends of global mean surface temperature since the late 19th century, Science Advances (2018). DOI: 10.1126/sciadv.aao5297 Chris K. Folland et al.
Abstract
The time series of monthly global mean surface temperature (GST) since 1891 is successfully reconstructed from known natural and anthropogenic forcing factors, including internal climate variability, using a multiple regression technique. Comparisons are made with the performance of 40 CMIP5 models in predicting GST. The relative contributions of the various forcing factors to GST changes vary in time, but most of the warming since 1891 is found to be attributable to the net influence of increasing greenhouse gases and anthropogenic aerosols. Separate statistically independent analyses are also carried out for three periods of GST slowdown (1896–1910, 1941–1975, and 1998–2013 and subperiods); two periods of strong warming (1911–1940 and 1976–1997) are also analyzed. A reduction in total incident solar radiation forcing played a significant cooling role over 2001–2010. The only serious disagreements between the reconstructions and observations occur during the Second World War, especially in the period 1944–1945, when observed near-worldwide sea surface temperatures (SSTs) may be significantly warm-biased. In contrast, reconstructions of near-worldwide SSTs were rather warmer than those observed between about 1907 and 1910. However, the generally high reconstruction accuracy shows that known external and internal forcing factors explain all the main variations in GST between 1891 and 2015, allowing for our current understanding of their uncertainties. Accordingly, no important additional factors are needed to explain the two main warming and three main slowdown periods during this epoch.
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If the pause is caused by the sun it would seem to follow that all of the warming would be caused by the sun also.
Yes. The cause of the pause was the cause before the pause. Solar activity.
Our main conclusion is that the most robust influence on the 1998–2013 slowdown resulted from the cooling effects of reduced TSI forcing between 2003 and 2011
Fig 10 from my Solar Cycle Influence work:
I’m feeling vindicated – thank you very much.
And here I thought it was because I left the freezer door open.
“The time series of monthly global mean surface temperature (GST) since 1891 is successfully reconstructed from known natural and anthropogenic forcing factors, …”
I rceall Mary Shelley writing about the “successful reconstruction” of a living creature from spare parts by one Dr Frankenstein…..
Ya gotta admit that these people are inspired.
Precisely. (and I should have read your comment first or I would have refrained from posting mine, lol)
I’ve noticed this before. Other scientists have also concluded that natural processes have caused cooling. But they completely ignore simple logic: if natural processes can cause cooling then they must also be able to cause warming.
This must be true: if they could cause cooling, but no warming, then the climate would continuously get colder until presumably it reached absolute zero.
The reason for this nonsense is obvious: they are incapable of questioning the dogma, or they are afraid to. It’s very sad. In some ways we seem to be living in a dark age of science.
Chris
Right, so what branch of Climate Science is working on that solar thermostat project. These people are working under the premise that the world is populated by idiots and to prove it, here in the U.S. they are graduating kids from our urban public schools with on average an 8th grade reading proficiency and 4th grade math skills. All the better to dupe the little buggers
An issue is that the data bases they are using are so corrupted, it it difficult to actually find anything.GIGO.
Actually, IMHO it is because the data is so corrupted they can and have been finding EVERYTHING and ANYTHING (of course none of it is correct).
It wasn’t all that long ago that we were being told that there was no need to consider natural causes because CO2 was so powerful that it completely swamped all natural causes.
We’re making progress. No they are admitting that natural causes can stop the increase caused by CO2, how much longer till they admit that it’s possible that much of the warming over the last 150 years could have been caused by natural causes rather than just CO2?
You know…..no one has read that paper correctly
What the idiots are saying…..one time volcanoes…one time ocean…one time sun
…..if all three of those things hit at the same time…we’re in a ice age
“It wasn’t all that long ago that we were being told that there was no need to consider natural causes because CO2 was so powerful that it completely swamped all natural causes.”
You were never being told that.
From the NEW YORK TIMES
By Lisa Friedman and Glenn Thrush
Nov. 3, 2017
897
WASHINGTON — Directly contradicting much of the Trump administration’s position on climate change, 13 federal agencies unveiled an exhaustive scientific report on Friday that says humans are the dominant cause of the global temperature rise that has created the warmest period in the history of civilization.
https://www.nytimes.com/2017/11/03/climate/us-climate-report.html
“humans are the dominant cause of the global temperature rise”
Yes. They caused that variation. That doesn’t mean that natural variation has diminished, nor that it could contribute warming or cooling over shorter periods.
The analogy is Spring. The sun gets warmer every day. But that doesn’t cancel out weather. Cold snaps still happen. But they don’t stop the arrival of summer. The Sun is the dominant cause of that.
…But they don’t stop the arrival of summer. The Sun is the dominant cause of that….
That’s funny. I thought it was the tilt of the Earth. My old Geography teacher must have been wrong when he pointed out that when we have our summer, the opposite hemisphere has their winter….
Well, it’s the height of the sun in the sky. The point is that that is a steadily changing effect, but doesn’t override weather in the short term. However, weather is changing, and the sun keeps rising in the sky till summer comes. As it does.
Oh yes we are told that.
Javier – what a beautiful reply. That’s the whole thing right there – look at that idiotic bar chart, sorry Nick, I admire your tenacity but really you are undone by that chart.
That’ll leave a bruise…..
Javier, your plot supports Nick’s comment very well.
The boxplot is over a 60 year period with ~0.6°C of observed warming, or 0.1°C per decade. Natural internal variability has a 0.2°C range. So for the recent period in question (around 15 years), natural internal variability can indeed ‘swamp’ increases from greenhouse gasses, which without variability could be expected to be ~0.15-0.2°C. The IPCC view still holds.
That simply says that the nett effect of natural forcings on temperature rise over that period 1950-2010 came to about zero. It isn’t saying that natural forcings can’t have an effect over other periods.
It has never been claimed that CO2 forcing damps natural causes. Natural variation proceeds as it always did, and CO2 adds to it. The difference is that natural causes tend to have net zero effect over longer periods, as this chart shows, whereas CO2 forcing goes one way. That isn’t inconsistent with short term natural warming or cooling. That has always been happening and will continue, in addition to the AGW trend.
Nick
The co2 forcing is overestimated by at least a factor of three. When corrected, the chart reads quite differently.
What I read in your replies is a setup to be able in future to claim, as cooling continues, that it is natural variation that masks the AG forcing, that will come back to bite us in the ass. This argument was flighted by Gavin back in the days when the pause was admitted, before the rounds of padding temps.
I don’t see the upside of exaggerating the AG influence. It really sounds like ass-covering to save face for having made such excessive claims for so long. Sort of like buying time so ‘new discoveries’ can be used to tamp down the excesses of the past, while simultaneously entrenching certain policies for members of the green-industrial complex.
Monckton is right about the feedback error in the models; Willis is correct about the atmospheric response to volcanic dust; so the analyses showing ‘the models match the past’ is the result of parameter fitting, not physics.
Missing from the chart above is the natural corrective caparity (expressed in Watts per sq m potential) that are ample and multiple, and ignored. The claim that the cooling 1940-1975 was because of human emissions and volcanoes is laughable. Climate forecasters are still wrapped in their initial assumptions. A weaker ego and more perceptive eye will produce a more realistic chart of forcings.
Your memory is typically porous.
That is the implication when the purpose of the Paris Accord is to reduce the burning of fossil fuels. None of the other probable contributors, such as land use changes, were addressed. The IPCC explicitly exempted variations in the sun from having any significant influence.
The Paris accord addresses effects that we cause and can control. I think land use changes are included in net emissions. There is no use making an agreement about solar variation.
Now there’s a point. Can we control? If I look at the graph of total atmospheric CO2 over the last century, and try to spot Kyoto, Paris, the Clean Dev Mechanisms, the numerous certified emissions schemes, the Renewables Obligation, the Climate change act and the plethora of other national and supra national emissions policies that we’ve had since 1997, I would expect to see some dents in the graph after they were implemented. No? But alas, they are all but invisible on the CO2 trajectory. One could be forgiven for concluding that there’s no evidence whatsoever that any emissions policies for the last 30 years have had any effect at all on total atmospheric co2. And that by pouring ever more eye-watering sums into the policies that intend to reduce emissions is not only a waste of time and money, but the policies themselves do more damage than the purported warming would ever do… And even if we were to dent the graph – notch it downward to say 350, would that even result in any temperature fall just when we wanted it?
You are right, Nick Stokes. The warmests have always acknowledged that a Tamboro-sized eruption could temporarily overcome the warming power of increasing CO2. They have also acknowledged that a giant asteroid impact could have an even bigger, longer-lasting cooling effect on the climate. There may have been a few other hugely improbable scenarios that could happen naturally and disrupt the warming power of increasing CO2.
BUT NONE OF THOSE THINGS HAPPENED!
The point is, the warming power of CO2 is being disrupted by the natural causes that we were very explicitly told cannot disrupt the warming power of CO2. I do believe that was the meaning of Mark W’s original statement, that you knew what he meant, and decided to be disagreeable for the sake of being disagreeable, and to divert attention from the growing failure of the man-made global warming crisis theory.
The assumption that ‘routine’ natural climate variability is insignificant to the power of increasing CO2 in determining global atmospheric temperature is absolutely essential to the crisis theory. The assumption was used early to argue that late 20th Century warming was almost entirely due to increasing CO2, which, in a circular argument, supported the later idea that climate sensitivity to CO2 was high. And since, climate sensitivity was high, we were headed for a crisis.
Without the assumption of ‘weak’ ‘routine’ natural climate variability, All the wailing about a crisis is unfounded.
Skeptics have long maintained that even routine natural climate variability has been misunderstood, grossly underestimated and intentionally ignored in the creation of the global warming paradigm. This paper strongly supports the skeptical argument and undermines the global warming theory, which practically guarantees that it will be ignored or, at the very least, mischaracterized.
“The point is, the warming power of CO2 is being disrupted by the natural causes that we were very explicitly told cannot disrupt the warming power of CO2.”
I think you should quote what “we were very explicitly told”. I doubt that anyone said that natural variation would be any different with AGW active. What is true is that natural causes tend to cancel over longer periods. We know that, because they always have, even though longer can mean long in glacial cycles. We’re not looking at Milankovitch events here. So AGW prevails, not by suppressing natural variation, but by being unidirectional.
If I remember rightly, they assume the earth is in equilibrium with solar around the 1850. that allows them to eliminate the sun
THEY are making progress. They keep the grants, the journal editorships, the Professorial positions. They are like Soviet apparatchiks becoming Russian oligarchs, the ideology flips but they retain power, finance and prestige.
Does it really make even a little bit of difference whether they acknowledge that which became quite obvious several years ago?
Either they’re mistaken or we’re living through the greatest coincidence in the history of the universe. In “busting the pause”, Karl also found that the temperature trend from 1950-1999 was virtually identical to the trend from 2000-2014. Now they’re saying that completely unrelated changes in the Sun and volcanic activity on Earth have, by chance, created a cooling effect that exactly matches CO2’s warming influence. What are the odds against that happening to a hundredth of a degree? Isn’t is simpler and more reasonable to believe that the hypothetical feedbacks associated with CO2 have been exaggerated and TCR is actually extremely small?
A reduction in total incident solar radiation forcing played a significant cooling role over 2001–2010
As we would expect because a 0.1% change in TSI equates to a 0.07C change in temperature.
On the other hand, their TSI input is not correct. There has been no secular increase during the 20th century: http://www.leif.org/research/EUV-Magnetic-Field.pdf
Yes. The Modern Maximum.
If you look carefully at your graph of the Modern Maximum, you’ll notice that activity now is on par [or even a bit less] with what it was back around 1900 thus has no secular change since 1900, while the wrong TSI used in the paper has a marked variation. You have been fooled by your bias.
http://www.leif.org/research/Wrong-TSI-Anomaly.png
to make it clearer for you.
Lief Can you summarize for us dummies exactly what you are saying?
Leif, like Alan, I’d appreciate an explanation — even just a caption below the graph you linked to! When I look at your graph, I see an upward trend of increasing TSI(?) until about 1960, then flat to declining until about 1975, and then strong sinusoidal oscillations until the present. That is, there seems to be a strong correlation between your graph and historical temperatures. What am I missing?
That graph is from the paper of the post, and is as I pointed out wrong. There is no long-term upward trend.
There are several TSI reconstructions significantly different, and we have problems measuring TSI in the space age. So your confidence that you know what the correct TSI was in the past is unfounded.
Javier: Applied to Dr. Svalgaard, the term should be “the certainty monster”.
Your confidence that the ‘official’ TSI is correct is by the same token unfounded. I have explained very carefully my reasons for my confidence in my reconstruction of TSI. Show where that goes wrong, if you want to be taken seriously.
They say the biggest factor behind the Pause is reduced solar irradiation. Not precisely what you have been saying.
I thought we’d all gotten past considering TSI changes directly, because the evidence suggest the spectrum of the radiation changes more significantly than the TSI and it’s that change in relative emissions that’s significant to various natural processes
I have yet to see any kind of proposed index to account for the different spectral composition at different levels of TSI. Perhaps an integration of the spectral curve weighted with the energy of the photons of different wavelengths would be a good first cut.
Clouds. Nightime clouds vs daytime clouds, high thin cloud cover vs low thick cloud cover, high latitude clouds vs low latitude clouds, clouds over oceans vs clouds over land all will have some effect upon what TSI reaches where. Add to this a better understanding of how the oceans store the energy they receive, how they transport it and how they release it and we might start to understand why total TSI varying so little does not seem to correlate well with temperature over long periods of time.
If Natural Causes can cause a pause, why can’t they cause warming and cooling?…Becuase they can and do. CO2 doesn’t play into the picture.
I’m happy to see the study which concedes that natural factors play a role in the changes in temperature. However, the report doesn’t support the nonsense claim that “CO2 doesn’t play into the picture”. It’s assertions like this that make it easy for warmest to dismiss skeptics. Please don’t provide them the fuel.
I’m happy to see the study which concedes that natural factors play a role in the changes in temperature. However, the report doesn’t support the nonsense claim that “Unicorns don’t play into the picture”. It’s assertions like this that make it easy for Unicornists to dismiss skeptics. Please don’t provide them the fuel.
I have to agree with The Other Phil. We live in a world and time when alarmists can say any ridiculous thing and be unquestioned in the mainstream, but skeptical statements are like chum in the shark tank. They will be torn to pieces.
CO2isLIfe could have made a more defensible statement by adding just a few words: “CO2 doesn’t need to play into the picture.”
The entire crisis argument is devoid of definitive statements, protecting it from being falsified. We tend to think the power of persuasion is the product of being right. Not true. Persuasive power is the product of hyperbole and being immune to being proven wrong.
Selection bias is mandatory to get published in the CO2 biasene era.
Everything is CO2-induced warming except the events that are identified as cooling, where the effect of the event exceeds the CO2 effect. No consideration is given to the well-known pre-industrial (natural) heating that has occurred in recorded history. This confirmation bias renders their analysis useless.
OMG….Are they FINALLY getting it ?
No, just positioning with published excuses
So they finally admit there is a recent ‘pause’ but once again trip over saying when the temperature goes down it’s natural and when it goes up it’s AGW. Must be a full court press on at the alarmist camps trying to figure out ways to discount nature and get people to believe it. Truth is no one cares anymore if the sky is falling.
Given that socialist Western ‘governments’ are busily engaged in the total destruction of Western civilisation and the ethnocide of their peoples, no, people really are not concerned about the climate.
OT, but very interesting…for the curious space nuts like me…( and urgent..2 pm EST )
NASA stokes curiosity, preps ‘major announcement’ about red planet discovery
http://www.foxnews.com/science/2018/06/07/what-has-nasa-found-on-mars-get-set-for-major-announcement.html
Consider, if you will, a planet. A planet occupied solely by robots.
Robots made by an alien species from another planet.
Science fiction?
Molecules, yawn
“It’s life Jim, but not as we know it…”
I listened to their live feed (until they brought on some middle school class questions). The discussion of the limitations of the current on-planet soil/rock spectrometer assets was interesting, as well as the improved assets just getting on orbit now and planned lander assets set for 2020.
Toddler steps exploring the near solar system… First you crawl. Then you walk. And finally, you run!
Book, by geologist Prof. Ian Plimer: Heaven and Earth, global warming: the missing science examines warming/cooling climate changes in this present warmish inter-glacial-ish period, back through to geological timescales of hundreds of millions of years.
This attempt by the UK Met Office et al to restrict the the debate to post 1891
& blame mankind for warming & natural forces for cooling is nothing short of pathetic: we’ve been in & out of tropical & ice ages for billions of years, FFS, with absolutely no corrrelation with CO2, never mind the negligible proportion of CO2 in the atmosphere which is man-made.
http://www.biocab.org/Carbon_Dioxide_Geological_Timescale.html
John Doran.
so….volcanoes, La Nina, the sun…..looks like they covered all their bases
…except for one
The one where they tell us every time the science is settled…and their latest paper is correct
One comforting factor about such results is they suggest that natural influences did not stop in 1950 with the rise of CO2 as is often claimed
So when volcanic activity decreases and temperature goes up that is CO2. When clouds decrease because of the increase in temperature caused by a reduction in volcanic activity wth consequent warming, that’s CO2. When it’s relatively warmer recently because historical temperature measures were adjusted down that’s CO2 as well I assume. /sarc off
Over the pause the CO2 + feedbacks was supposedly getting stronger yet the pause remained ie the negative forcing must have been getting stronger to prevent a rise.What a coincidence. Or are we still coming out of the Little Ice Age?
Need I go on?
Warming Period 1911 – 1940 “. . . increases of greenhouse gases contribute significantly to the early 20th-century GST warming trend . . ”
That’s just plain nuts.
Who’dda Thunk!
They went looking for a reason for recent “pauses” with a possible explanation in mind that wouldn’t upset their apple cart, and By Golly, they were RIGHT!
That silly business of having an open mind in research only gets in the way of confirming what you already knew was correct.
(A textbook example is the Doran and Zimmerman “97%” study.)
Cooling is Gaia’s last gasp effort to survive the onslaught of man’s inhumanity to nature.
And I thought the science was settled. Clearly these people are deniers.
They have not gone far enough. This is the first inning of the cooling which I have been predicting, now that solar conditions have finally met my criteria.
Those two conditions being 10+years of sub solar activity in general and within the sub solar activity in general, low average value solar parameters equal to or exceeding that associated with typical solar minimums between normal sunspot cycles while longer in duration then those typical solar minimums.
Year 2018 being the first year since the Dalton that solar conditions have been met this criteria which can cause a significant climatic change.
Going forward the cooling will continue as long as solar activity remains sub par.
Year 2018 going very well thus far and according to what I was expecting.
Again very low solar equates to lower overall sea surface temperatures and a slightly higher albedo which equates in turn to global cooling.
All of the solar influences being compounded by the weakening geo magnetic field.
I think AGW theory is on it’s last legs and within two years from now will be shown to be false, not that it isn’t already.
For the best of me, I can not remember the name of this guy that first stated that:
“A tragedy, is only a misunderstood (or misinterpreted) comedy…..
Any help here or there, with that guy’s name, very much appreciated….thanks.
cheers
“A tragedy, is only a misunderstood (or misinterpreted) comedy…..” — unless it happens to you. Then it is a tragedy. A tragedy is what need not have happened, but did.
So the Met are still playing ‘find the lady ‘ ! But who can blame them this game has after all brought them considerable funding , despite the fact they got no beater at their ‘day job ‘ of weather prediction .
And that climate ‘science’ is once again using the ‘heads you lose , tails I win’ anti-science approach comes as no surprise at all. After all to date they never been able to says what would ‘disprove ‘ their theory despite this is being a standard element of the scientific approach widely accepted as a norm in science for over 200 years .
knr
After all to date they never been able to says what would ‘disprove ‘ their theory despite this is being a standard element of the scientific approach widely accepted as a norm in science.
——————–
knr,
They do not have to be able, or claim the right to be able or allowed or proclaim such right or allowance as to pretend, say or forward the point that :
” what would ‘disprove ‘ their theory despite this is being a standard element of the scientific approach widely accepted as a norm in science ”
They simple have to accept and recognize and abide to the conditions and requirements that could or may ” ‘disprove ‘ their theory” (as in the standard element of the scientific approach ) … A basic simple requirement from and for the ones that forward and propose a scientific hypothesis or a scientific proposition in principle, or any hypothetical evaluation in a given condition.
The other way around could be anything but not fair or scientific, regardless of the power “shining” through authority position, or any expert celebrity status position….or any kind of “superior” expertise from propagated or proclaimed position of the status quo of the “authority” forwarding and supporting a hypothetical or scientific “problem”….so to speak.
cheers
“Yeah, re natural variation and ocean oscillations, we found sceptics’ footprints all over the place when we finally got there. But, since we got here, we understand that sceptics have now shown that volcanics are only very temporary blips. The le Chatelier Principle kicks in to resist an agent of change like aerosols by reducing cloud cover and letting more sunshine through. It seems that earth sea and atmospheric components cooperate to resist temperature change. We wont go there until we have to”.
“Next thing you know, they will be demonstrating a law of natural modulation of earth temperatures but we will be retired before we have to confront that.”
I get it, when it’s cool/cold it’s natural, when it’s warm/hot it’s caused by anthropogenic CO2. The weather system is soooo clever. As are our (unbiased) friends from the Met.
Re the amount of recent warming caused by the Sun, my recent paper estimates 33%-37% in two different ways over the period 1980-2001.
This is a (long) summary of my paper “On the influence of solar cycle lengths and carbon dioxide on global temperatures”. Recently published by the Journal of Atmospheric and Solar-Terrestrial Physics (JASTP), it is a rare example of a peer-reviewed connection between solar variations and climate which is founded on solid statistics. It is available at https://doi.org/10.1016/j.jastp.2018.01.026 (paywalled), or https://authors.elsevier.com/a/1X30-4sIlkaszt (free access until July 4th 2018), or in publicly accessible pre-print form at https://github.com/rjbooth88/hello-climate/files/1835197/s-co2-paper-correct.docx .
The paper builds on the work in the 1990’s by Friis-Christensen and Lassen, by adding a CO2 element to their model based on solar cycle lengths (SCLs). By using a linear regression model, statistical significance levels can be measured for these two effects. Using HadCRUT4 as the global temperature series, averaged over 11-year periods starting 4 years before solar cycle maximum, the CO2 variable is hugely significant, as it explains the overall upward trend, while the length of the previous cycle has a 1.3% significance level (more on this below), and this variable explains the wiggles in the graph which is Figure 1 of the paper.
The upshot of the analysis is an estimate of TCR (Transient Climate Response) of 1.93K, and of ECS (Equilibrium Climate Sensitivity) of 2.22K. Under an assumption of continuing increases of CO2 concentration by 2 parts per million each year, the expected HadCRUT4 anomaly in AD2100 is only 1.1K higher than it was during the period 1996-2006.
Allowing for the SCLs does make material (but not vast) differences:
• without them the TCR estimate would be 2.37K instead of 1.93K
• they explain 37% of the observed warming between 1980 and 2001
• without them the residual errors significantly differ from the model assumptions
The paper also considers two other types of model, one being Scafetta’s based on 20- and 60-year cycles plus a quadratic component, the other using estimates of radiative forcings from various sources such as the Sun, well mixed greenhouse gases, and aerosols. One Scafetta model actually provides by far the best fit to the HadCRUT4 data, while the best radiative model gives a very similar estimate for the Sun’s contribution to global warming between 1980 and 2001, namely 33%. That model also implies that global temperatures are much more sensitive to solar (short-wave) radiation than to greenhouse (long-wave) radiation, by a factor of nearly 3.
And now, a few words on the statistics. For “layman” readers the meaning of the 1.3% above is that if there really is no solar effect, then it was an 80 to 1 shot or so against these observations having occurred. Of course, 80 to 1 shots do sometimes happen by chance, but…
For more mathematical readers, it is worth noting that compared with a lot of climate papers the statistics are pretty rigorous, with quoted significance levels rather than mere correlation values, and distributional tests on the residuals – specifically the Durbin-Watson (DW) test, which can detect missed low frequency effects as well as true serial correlation. This paper uses exact calculations of DW significance via algorithms from my Ph.D. thesis of 40 years ago. There are still papers published which use the ancient bounds on DW significance rather than the exact values, and to help others to benefit from these calculations, I have provided ‘R’ code for them in the SI.
One reviewer suggested that in addition to quoting values for Root Mean Square Residual , F-statistics, and DW, I use the Akaike Information Criterion (AICc). In so doing I discovered an apparently novel feature, which is that while it is widely assumed that AICc is independent of and superior to an F-statistic, in the case of 1 additional regressor (= 1 degree of freedom lost) there is an approximate relationship between AICc and F. This constitutes a rule-of-thumb that if AICc favours the additional regressor then F has a tail area less than 12%.
The paper also contains one or two other “titbits”. For example, in order to allay reviewers’ concerns that natural short-term autocorrelation might persist into the 11-year bins which were chosen to match the mean solar cycle length, Appendix A conducts a study of autocorrelation. The most surprising thing to emerge is that there is a strong 18-year autocorrelation of temperatures, which one might guess corresponds to the period of precession of the Moon’s ascending node on the ecliptic.
Also, Appendix C introduces a model for lagged ocean warming in order to arrive at the difference between TCR and ECS quoted above. This difference is somewhat less than appears in IPCC documents, but it arises from the observation that between solar Cycles 14 and 23 the oceans warmed by three-quarters as much as the land, which leads to a half-life for the lag being 20 years, and ECS/TCR = 1.15. This model appears quite plausible.
Finally, though it has only a minor bearing on the results, it irked me that the solar “authorities” declared that the Cycle 22/23 minimum was at 1996.9 when that date is later than both of the observed 13-month smoothed minima at May 1996 and August 1996. So Appendix B studies the differences between mirrored values at m-x and m+x about a putative minimum month m, and uses the signs thereof to conclude that the minimum was no later than July 1996, i.e. 1996.5. This then made Cycle 23 12.4 years long instead of 12.0.
Rich.
Acknowledgment of the pause in a big deal. Has Al Gore received the memo?
“Acknowledgement of the pause in a big deal.”
Far from it. The IPCC AR5 of 2013 devoted a special box to the issue: