Statistical analysis shows pattern consistent with pre-industrial temperature swings, study concludes
From McGill University’s Shaun Lovejoy
Statistical analysis of average global temperatures between 1998 and 2013 shows that the slowdown in global warming during this period is consistent with natural variations in temperature, according to research by McGill University physics professor Shaun Lovejoy.
In a paper published this month in Geophysical Research Letters, Lovejoy concludes that a natural cooling fluctuation during this period largely masked the warming effects of a continued increase in man-made emissions of carbon dioxide and other greenhouse gases.
The new study applies a statistical methodology developed by the McGill researcher in a previous paper, published in April in the journal Climate Dynamics. The earlier study — which used pre-industrial temperature proxies to analyze historical climate patterns — ruled out, with more than 99% certainty, the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate.
In his new paper, Lovejoy applies the same approach to the 15-year period after 1998, during which globally averaged temperatures remained high by historical standards, but were somewhat below most predictions generated by the complex computer models used by scientists to estimate the effects of greenhouse-gas emissions.
The deceleration in rising temperatures during this 15-year period is sometimes referred to as a “pause” or “hiatus” in global warming, and has raised questions about why the rate of surface warming on Earth has been markedly slower than in previous decades. Since levels of greenhouse gases have continued to rise throughout the period, some skeptics have argued that the recent pattern undercuts the theory that global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels.
Lovejoy’s new study concludes that there has been a natural cooling fluctuation of about 0.28 to 0.37 degrees Celsius since 1998 — a pattern that is in line with variations that occur historically every 20 to 50 years, according to the analysis. “We find many examples of these variations in pre-industrial temperature reconstructions” based on proxies such as tree rings, ice cores, and lake sediment, Lovejoy says. “Being based on climate records, this approach avoids any biases that might affect the sophisticated computer models that are commonly used for understanding global warming.”
What’s more, the cooling effect observed between 1998 and 2013 “exactly follows a slightly larger pre-pause warming event, from 1992 to 1998,” so that the natural cooling during the “pause” is no more than a return to the longer term natural variability, Lovejoy concludes. “The pause thus has a convincing statistical explanation.”
The methodology developed in Lovejoy’s two recent papers could also be used by researchers to help analyze precipitation trends and regional climate variability and to develop new stochastic methods of climate forecasting, he adds.
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The paper:
“Return periods of global climate fluctuations and the pause”, Shaun Lovejoy, Geophysical Research Letters, published online July 14, 2014. DOI: 10.1002/2014GL060478
Abstract
An approach complementary to General Circulation Models (GCMs), using the anthropogenic CO2 radiative forcing as a linear surrogate for all anthropogenic forcings [Lovejoy, 2014], was recently developed for quantifying human impacts. Using preindustrial multiproxy series and scaling arguments, the probabilities of natural fluctuations at time lags up to 125 years were determined. The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence. In this paper, this method is extended to the determination of event return times. Over the period 1880–2013, the largest 32 year event is expected to be 0.47 K, effectively explaining the postwar cooling (amplitude 0.42–0.47 K). Similarly, the “pause” since 1998 (0.28–0.37 K) has a return period of 20–50 years (not so unusual). It is nearly cancelled by the pre-pause warming event (1992–1998, return period 30–40 years); the pause is no more than natural variability.
Preprint paper here:
He has actually inadvertently stumbled upon a flaw in the models and in the alarmists idea that most 20th century warming was human related. Give them another 5 years and they might stumble on another idea that sensitivity to c02 is much less than they think. They need to look at the PDO and its interplay with the sun.
Climate is spring loaded to jump right back down from exactly the type of spikes that our hockey stick blade represents, as seen in the main Greenland ice core:
http://oi61.tinypic.com/2cxbxw4.jpg
Gee I wonder why recent Greenland warming isn’t also turned into a hockey stick! Thanks, mile think ice, Mike couldn’t blot you out or cherry pick you apart or hand wave you away even, though the later he tried but for that darn Internet and those rascally kids on it digging up old data.
what a condescending paper… “Even if the ex-post facto reconciliations proposed by [Guemas et al., 2013], [Schmidt et al., 2014] or [Mann et al., 2014] are correct, the damage has been done. Climate change deniers have been able to dismiss all the model results and attribute the warming to natural causes.” and “The two most cogent remaining skeptic arguments– that the models are wrong and the variability is natural – are thus either irrelevant or are disproved by the new approach”. Disgusting. How can this have passed objective peer-review? This is a very subjective and condescending manner of writing. I taste hatred through this words. A critical paper writing about “believers” and “alarmists” would never pass review… so how can this…?!!?
Of course they used NASA GISS… the most adjusted and tampered with data set you can get. I recently just showed how Hansen et al keep cooling the past and warm the present… How about using HadCrut3 and 4 as well. Would be nice to know if they get the same results.
Forgot to write that luckily lovejoy and others (finally) admit that “.. the models over-estimated the post-1998 El Nino global temperatures: they did not anticipate the “global slow-down” [Guemas et al., 2013], “hiatus” [Fyfe et al., 2013], or ”pause” [Slingo et al., 2013].” 1:0 for the skeptics and deniers!!!!
I really don’t care about this guy’s take on the statistical range of natural variation. If he wants to claim that we are currently witnessing such an event and that it is strong enough to overcome CO2 forcing, then he needs to identify the physical elements of natural variation that he claims are responsible. If he cannot identify them, then there is no reason to believe that they are currently in play. To simply claim that they must be in play because a high level of CO2 forcing is a given and because statistical variation allows for it is not science. It is assumption driven pseudoscience.
OK, lets see … according to Lovejoy:
From 1998 – present, we have had a ‘natural variation’ cooling event.
From 1992 – 1998, we had a ‘natural variation’ warming event, of somewhat greater magnitude.
That means that ‘global warming’ occurred before 1992. IPCC says that anthropogenic ‘global warming’ cannot have been much of a factor prior to 1950, as the global CO2 hadn’t really budged yet.
HadCRUT3 global surface temp trend 1950-1992 …. 0.08C per decade. That is 0.8C per century – 5 to 10 times less than the scary stories they tell. And of course, that 0.8C is tallied before one accounts for things like the climb out of the Little Ice Age, the bigger Ice Age, etc.
Whoop-dee-doo.
Which of the 100 or so models in their Texas Sharpshooter battalion picked 0.8C/century?
And there I was thinking natural variation was “global warming” …
“Lovejoy’s new study concludes that there has been a natural cooling fluctuation of about 0.28 to 0.37 degrees Celsius since 1998 — a pattern that is in line with variations that occur historically every 20 to 50 years, according to the analysis.”
The corollary to this “finding” is that a similar proportion of the warming from 1975 to 1990 was also attributable to natural fluctuation.
Now IIRC the global temps rose about 0.5K in the last half of the 20th c.
That leaves 0.13 to 0.22 degree C in 50 years as amount attributable to AGW and other anthropogenic causes.
Now to play the warmist game : “if that trend continues” we can expect global temperatures to be “as much as ” 0.4 degree celcius warmer by the end of this century.
What these clowns don’t seem to have realised yet is that you can’t have your cake and eat it.
The harder they twist the figures to ‘explain’ the pause, the more they prove that the remarkable warming that had everyone panicking in 2001 was ALSO to a large degree natural.
You can call this a message to the Greens with both love and joy.
Goldie says: “If these people are that confident that they now know what the “natural variability” factors are; they should incorporate them into the models and then publish their findings.”
If natural variability is just noise around good models (which I think is the essence of the author’s argument), then doesn’t that just mean the modelers have grossly underestimated the error bars? But if they increase the error bars too much, they include no temperature increase and falling temperatures. That kind of interferes with the narrative.
On the other hand, if they think they can predict the natural variability, they should, as you suggest, do that and make predictions with error bars by combining their climate models with their natural variability models. Then we can wait and see if they come true.
Someone looked at some random stars in the sky and decided they looked like a Big Dipper, but someone else decided they looked like a Great Bear.
The first person said, “Bears don’t have long tails.”
The second person created a myth, “How The Bear Lost Its Tail.”
That’s how it works, in the worlds of star-gazers and Climate Scientists.
http://www.amazon.com/How-Lie-Statistics-Darrell-Huff/dp/0393310728/ref=sr_1_1?s=books&ie=UTF8&qid=1406011779&sr=1-1&keywords=how+to+lie+with+statistics
I’ve been waiting for the wheels to fall off this bus for about ten years. Is it finally happening? You know the worst thing about it, when it finally happens, we still won’t get any satisfaction. When communism collapsed, all the hard left just melted away. They never really admitted they were wrong. (Actually, they just morphed into greens. ) How about the peak oil fanatics? The real estate never falls types? All the alarmists will just disappear…or move onto the next scare.
Hang on a minute, I was under the impression that the post war cooling that Lovejoy attributes to natural variation, was firmly attributed to fine particulate and SO2 aerosol cooling. So which one do they want. They cant have it both ways.
Mosher….?
dbstealey,
Thank you for the link to woodfortrees, but could I get a clarification of the significance of 1997? I was under the impression that an interval of less than twenty years was not typically considered to be of statistical significance when calculating temperature trend, but when I insert pretty much any year prior to ’97, a warming trend seems apparent. This applies to (I believe) every temperature record available via the site, calculated over any timeframe greater than 20 years. I’m clearly confused, could you assist? Is this due to fudged/corrupted datasets, or am I using the site incorrectly? Thanks in advance.
I think we should make more of the 50/50 ‘consensus’ amongst the warmists. It seems that half of them are adamant there is no pause and the other half have accepted there is a pause and are imaginatively explaining it away.
Desperation is increasingly gripping the CAGW crowd. The Warmistas are running round in ever decreasing epicycles in search of answers to Nature’s stern commands. If temperatures go down, then it’s natural variation, if they go up, then it’s climate change for the Warmistas. The Warmistas are desperately adjusting the past colder and the present warmer, They ask “Is the warming hiding in the deep oceans?” ….more likely it is escaping to outer space as usual.
I apologise in advance to all other commenters – with well over 100 comments already I have not read them all and some will no doubt already have said what I say here:-
This paper is surely one of the biggest pieces of absolute nonsense ever to masquerade as a scientific paper:
“More troubling, the models over-estimated the post-1998 El Nino global temperatures: they did not anticipate the “global slow-down”, “hiatus”, or ”pause”. Even if the ex-post facto reconciliations proposed by [..] are correct, the damage has been done. Climate change deniers have been able to dismiss all the model results and attribute the warming to natural causes.“.
That’s not science, that emotional advocacy. Emotive / pejorative terms such as “troubling”, “damage” and “deniers” have no place in a scientific paper (and that was just the introduction). How on earth could this have got past the editor, let alone peer-review?
There’s more specific absolute nonsense just a few sentences later: “The two most cogent remaining skeptic arguments – that the models are wrong and the variability is natural – are thus either irrelevant or are disproved by the new approach. [..] The basic hypothesis is that the global temperature anomaly [..] is the sum of an anthropogenic component – assumed proportional to the observed CO2 forcing – and a residual representing the natural variability.“.
There’s that pejorative language again (“sceptic”), but leaving that aside their logic is absolute nonsense. They claim to have disproved (their word) that natural variability played a major role and that therefore the observed temperature change was anthropogenic. But, as they point out, they have assumed it was anthropogenic in the first place, that the anthropogenic effect is linear, and that the natural variability can be determined as the residual after their assumptions have been applied.
It is absolutely mind-boggling that such appalling circular logic can even reach the peer-review process, let alone pass it.
Partial extent of the short term (multi-decadal) natural variability (cooling/warming) for the N. Hemisphere can be calculated from the oscillations in the geomagnetic field (combination of the solar and earth’s internal ‘oscillations’).
1910-1932 = 22 years +0.3C warming
1932-1955 = 23 years ~0C pause
1955-1975 = 20 years -0.5C cooling
1975-2002 = 27 years +0.6C warming
thus, total warming as derived from geomagnetic field since 1910 is of order of +0.4C.
Since there are other natural factors such as the ENSO, volcanic eruptions, etc (which appear not to be linked to geomagnetic variability, e.g. current pause started around 1995), the numbers quoted above only one part of the overall natural variability factor.
Confused and genuine question – every year on Jan 1st for the last 10 years, the BBC have stated that the previous year was the warmest on record and something similar to saying the last 10 years have been the warmest on record. How on Earth can thus statement fit in with the Earth has been cooling for the last 17 years ?
He’s using the Wahl and Ammann “Jesus paper” again, so IMHO this article should never have been published. ‘Nuff said about another sad little chapter in the history of Climate Junk Science 🙁
Natural variability can explain cooling but not warming???
And this paper tells us what that we didn’t know (or think) already?
It claims natural variation did it. Breaking news – so do ‘99.9%’ of sceptics!
That’s the whole damn point – that human influences on long term global climate temperatures are so tiny as to be effectively lost in the noise of….natural variation.
Imagine if this paper had instead been authored by a sceptic and arrived at roughly the same conclusions, but was coming from the other end of the spectrum. ‘It IS natural variation after all’. Would it have even seen the light of day?
And where does this fit with yesterdays offering from Lew’ – or the other dozen or more ‘explanations’ already offered? CAGW theory is all over the place.
The good professor Lovejoy doesnt need a phd to play this game, its known to kids around the world as snakes and ladders.His ladders represent manmade warming his snakes represent natural cooling. All you have to do when designing your game board is cherrypick your start point lets say the mythical start of the industrial revolution instead of the mwp or lia.this helps link your manmade warming ladder to mans emmissions and ensures your game board is rigged with more manmade ladders than natural cooling snakes, you cant fail to win eventually.then when you reach the top of the board you can draw a linear trend line back to the start and hey presto a winner every time . Bet he cheats when he plays the kids