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:
The subject paper, Mr. Watts set up and following comments are confusing. It is hard to know what the paper is really about until you get to Mr. Lovejoy’s conclusion. Mr. Lovejoy seems to be saying that AGW is real, but to help convince the “skeptics” of that, it may be necessary to make the case with less dependence on climate models because “skeptics” are skeptical of the models. He is not saying there is a problem with climate models but that since “skeptics” like them, there is plenty of other evidence that can be used to make the case.
From Mr. Lovejoy’s conclusion:
“As data and models have improved, the thesis of anthropogenic warming has
become increasingly convincing, and today we appear to be reaching a state of small
incremental improvements. Unless other approaches are explored, the AR6 may
simply reiterate the AR5’s “extremely likely” assessment (and possibly even the
range 1.5 – 4.5 K). We may still be battling the climate skeptic arguments that the
models are untrustworthy and that the variability is mostly natural in origin. To be
fully convincing, GCM-free approaches are needed: we must quantify the natural
variability and reject the hypothesis that the warming is no more than a giant
century scale fluctuation. With the help of nonlinear geophysics ideas on
fluctuations and scaling, this has been done. By lumping all sources of natural
variability together (i.e. internal and external) and by using the CO2 forcing as a
surrogate for all anthropogenic effects, it is possible to avoid assumptions about
radiative effects of aerosols, cloud radiation feedbacks and other difficult issues.”
Winston says: July 22, 2014 at 7:22 am
Earth’s magnetic field is important for climate change at high altitudes
(23 May 2014)
http://www.antarctica.ac.uk/about_bas/news/news_story.php?id=2630
………………………………..
I did some research into correlation between the Earth’s magnetic field change and climate indices.
It appears that the climate change boundary conditions for the N. Hemisphere are set annually, i.e. it is not the absolute intensity, but it is the annual differential that governs natural variability.
“To be fully convincing, GCM-free approaches are needed: we must quantify the natural
variability and reject the hypothesis that the warming is no more than a giant
century scale fluctuation. ”
Who says we must reject natural variablity ?
Reality of the dominant nature of natural variability over green house gases is faintly being perceived by the alarmists , not accepted but realized never the less. The warming phase of the 60 year climate cycle happened 1910-1945 and again 1970-2000 . The century scale natural variability of a cooling climate is just getting underway.
steven s,
Random is an oft abused term in my opinion.
1. There is truly random, as in quantum uncertainty. We don’t know something because it doesn’t actually have a fixed value until a measurement / observation is made. I don’t think this is applicable here.
2. There is chaotic random, as in the weather. We actually have a decent idea what’s going on, but the nature of the math is such that iteration to iteration, very small differences in initial conditions cause very large changes in the overall system. For all practical purposes, we can’t predict weather very far out even though we understand the mathematical relationships pretty well. This may or may not apply to climate AFAIK, I’ve heard arguments both ways.
3. Finally there is random as in complicated. We sometimes treat very complex things that may be deterministic as if they were random because it’s too darn difficult to account for every factor. This probably applies to some extent to the climate. Not all models ‘model’ everything about the climate.
For those of you concerned about NOAA’s coronation as the hottest June on record, please be advised: NOAA’s own agency, NCEP, doesn’t agree
https://mobile.twitter.com/BigJoeBastardi/status/491425758745604096/photo/1
Neither does the satellite data. NOAA seems to have the worst record wrt correctly adjusting the data.
(Thanks goes to Joe Bastardi for the info.)
From the Independent:
“A new study has found that global temperatures have not flat-lined over the past 15 years, as weather station records have been suggesting, but have in fact continued to rise as fast as previous decades, during which we have seen an unprecedented acceleration in global warming.
….
Two university scientists have found that the “pause” or “hiatus” in global temperatures can be largely explained by a failure of climate researchers to record the dramatic rise in Arctic temperatures over the past decade or more.
When Kevin Cowtan of York University and Robert Way of Ottawa University found a way of estimating Arctic temperatures from satellite readings, the so-called pause effectively disappeared and the global warming signal returned as strong as before.”
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What satellite readings are being referred to?
How is the estimate of temperature made?
Perhaps Dr Spencer, or anyone els who may about this sateelite data, may enlighten us
If natural variation rules in a period of rising CO2, it always rules.
Felix says:
July 21, 2014 at 5:36 pm
Give it up guys ….
“The combined average temperature over global land and ocean surfaces for June 2014 was the highest on record for the month, at 0.72°C (1.30°F) above the 20th century average of 15.5°C (59.9°F).”
http://www.ncdc.noaa.gov/sotc/global/2014/6
[what, you think the temperature won’t ever go back down? -mod]
Just an FYI. The above Felix is not the Felix writing now. So, I guess I’ll re-register as Not The Other Felix, (NTOF) so as not to confuse folks. Only post rarely, but I wouldn’t want to be . . . um . . . confused with another poster.
Sincerely,
NTOF
Ulric Lyons says:
July 22, 2014 at 10:44 am
“Then with the weaker levels of solar activity since then, solar forcing has just been able to maintain a steady global mean T, hence the recent lack of a warming trend.”
I couldn’t agree more Ulric.
**** **** ****
vukcevic says:
July 22, 2014 at 11:28 am
“I did some research into correlation between the Earth’s magnetic field change and climate indices. It appears that the climate change boundary conditions for the N. Hemisphere are set annually, i.e. it is not the absolute intensity, but it is the annual differential that governs natural variability.”
I’m curious as to what you mean by this.
“Grasping at straws”, by Shaun Lovejoy.
It doesn’t matter what caused the lack of warming for the last 17+ years. They didn’t see it coming. The whole Climate change, with only negative consequences, assertion, is based on warming. The only driving factor was anthro. Co2. Anything else was insignificant. This was the official line of the alarmist dictatorship only a few short years ago. Maybe now they should admit their errors and acknowledge that there are Natural drivers after all, with far greater influence on our climate than Co2. Oh, hang on. I think Lovejoy’s paper has done just that. Well, it’s a start.
Avery Harden says:
July 22, 2014 at 10:47 am
“By lumping all sources of natural variability together (i.e. internal and external) and by using the CO2 forcing as a surrogate for all anthropogenic effects, it is possible to avoid assumptions about
radiative effects of aerosols, cloud radiation feedbacks and other difficult issues.”
Yes but if, for example, the post war cooling is attributed to natural variability, then it ignores the short term effects of the aerosols and vulcanism that is not related to CO2 and cant be lumped into a single proxy. What it does is to over-estimate the natural variability impact which then in turn over-estimates the underlying CO2 forcing that it is masking. Im not saying that the entire concept is wrong, just that it doesnt seem to accurately capture the real variables at work.
Good lord.! It is so painful to watch these people twist in the wind, going through so many tedious mental gyrations in order to maintain this failed AGW belief system. Wouldn’t it be much simpler to just reject the theory rather than inventing so many new ones to keep it afloat?
The following is my explanation of the Antarctic ice extent quandary, peer reviewed by a knowledgeable colleague:
SCHROEDINGER’S ICE. It is both there and not there, with a probability of 0.5 maybe. But looking at the ice to verify whether it is / is not there collapses the quantum wave function.
Turney and his Ship of Fools looked, and look what happened to them.
I’m sorry if I missed anybody else saying this, but if this study is correct we should be rejoicing and trying to reverse any reduction in CO2 emissions.
You see, if CO2 is responsible for warming the earth, and natural variation is responsible for the present ‘pause’, then if the CO2 levels were not still rising, the average temperatures would be falling, and falling rapidly. If this study is correct then Arrhenius was right and we can, and are, preventing an Ice Age.
Mike Tremblay, if you take in all the news on this for the week, what you get is that ENSO is the primary natural variability that creates the current temperature “pause” just as it created the exceptional high in 98. The elephant in the room, the ocean sloshing about, is becoming more evident as the heat sink that turns the knob on the atmosphere temperatures. If the ocean is getting warmer, well, that could be a problem.
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.
This is Mann’s Yamal hockey stick, Mike’s nature trick and Marcott’s fabricated uptick all rolled into one. At the core of this, Lovejoy is comparing recent instrumental temperatre data with averaged proxy data.
He knows very well (as did Marcott) that proxy data – especially averaged from multiple sources, will be squashed flat and have reduced variation. Different proxies give differing results so averaging them will iron flat historic temperature variation, making recent instrumentally measured variation (coincidentally an upturn in the last half-century) seem anomalous.
This is a central trick of the AGW conjurers. It is pure fraud, however it is dressed up. This is Mike hiding the decline. You can compare instrumental with instrumental, or proxy with proxy, but NOT proxy with instrumental. If you are honest that is.
By contrast this study, comparing apples with apples, finds not that the recent warming is anomalous, but rather that the little ice age is the biggest down-fluctuation in temperature of the whole Holocene:
http://www.whoi.edu/science/GG/paleoseminar/pdf/obrien95.pdf
Meanwhile this study, from 1973 in the pre-politicised era of climate science, comes to a similar conclusion and finds ongoing warming as a rebound from the little ice age as the normal predictable outcome:
http://www.sciencedirect.com/science/article/pii/0033589473900409
Climate is recovering, in a fully predictable way, from the little ice age. Climate science meanwhile continues to go steeply downhill.
Here’s another one on Holocene variation:
http://yly-mac.gps.caltech.edu/AGU/AGU_2008/Zz_Others/Li_agu08/Mayewski2004.pdf
Looks like people across the world agree with the blogs expressed on this track . GWPF carries an interesting commentary on a new global survey by IPSOS MORI. Quoting GWPF,
Global Survey: Climate Scientists ‘Don’t Know What They’re Talking About’
Date: 23/07/14
Lewis Page, The Register
People all around the world, responding to a new global survey by Ipsos MORI, have generally agreed with the ideas that scientists don’t really know what they’re talking about when it comes to the climate and that governments are using environmental issues as an excuse to raise taxes.
“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.”
I commend Mr. Watts for sharing yet another line of evidence that further reinforces the understanding that there exists a continual forcing that is causing a net upward long term trend in the heat content of the climate system that is either augmented or dampened by shorter term, natural, stochastic, and lower magnitude, heat redistribution events such as ENSO.
1) This is consistent with the Risbey paper which showed that any model run discrepancy between calc’d and obs’d mean global SATs are minimized when the emergent stochastic ENSOs in the model are in phase with the observed ENSOs.
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2310.html
2) This data is consistent with no pause in ice mass declines observed in the Arctic and Antarctic.
http://onlinelibrary.wiley.com/doi/10.1029/2009GL040222/abstract;jsessionid=5CC63C213C94CF82C29D3519069FF8C7.f03t03
3) There was no pause in the ocean heat content trend (0-2000 m)
http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/index.html
4) In the last 18 years, the temperature record shows excellent correspondence with short term well documented short-term cooling and heating events (natural variations). The link below illustrates the quality of the correspondence in the last ~30 years of volcanic activity (El Cinchon, Pinatubo) El Nino, La Nina and the very small solar effects.
If you remove the temperature skew by known natural variations, the upward trend is the same as the last ~30 years. No pause in the greenhouse gas forcing.
5) The trend usually cited starts with an 1998 El Niño (heat transfer from ocean to air) and ends with La Nina (heat transfer from air to ocean). This artificially gives the impression of a lower trend. Evidence is put forward for the origin of the natural air/ocean heat transfer mechanisms (Anomalous trade winds) explaining the short ‘hiatus’
http://www.nature.com/nclimate/journal/v4/n3/full/nclimate2106.html
6) Similarly, sea level trend pauses are explained by precipitation variations (increased during El Niño, diminished during La Nina) and was supported by direct evidence.
This weight of evidence explains the ‘pause’ very nicely in the absence of an alternative plausible explanation for that which stops for 17 years after rising for >75 years.
Now it’s time for all of us to get on the same page and determine how to adapt to and mitigate an ever increasing economic disruption due to climate change. Let’s work together.
hanzo says:
Now it’s time for all of us to get on the same page and determine how to adapt to and mitigate an ever increasing economic disruption due to climate change.
Hanzo is feeding at the taxpayer gravy trough, so naturally he wants that flow of loot to continue. But there is nothing that anyone needs to do. As I pointed out above:
The null hypothesis is the statistical hypothesis that states that there are no differences between observed and expected data. And since there are no differences between what is currently being observed and what happened in the past, the null hypothesis is not falsified. Global warming is natural.
The null hypothesis has never been falsified. It is a direct corollary of the scientific method, and it shows that there is nothing happening that is either unusual or unprecedented. Therefore, nothing needs to be done.
Global warming stopped many years ago, but the alarmist crowd, exemplified by hanzo, routinely disregards that fact. Because if they admitted it, their entire argument would be debunked, and any rationale for continued spending on ‘climate studies’ would be highly questionable.
New excuse for the ‘pause’: Negative phase of the natural Interdecadal Pacific Oscillation
http://hockeyschtick.blogspot.com/2014/07/new-excuse-for-pause-negative-phase-of.html
Excerpt:
“Matthew ‘say anything’ England is back with a new paper which offers yet another excuse for the 17+ year pause in global warming: the negative phase of the natural Interdecadal Pacific Oscillation (IPO) [excuse #14 by my count].”
OK, if you have computer models of a _phenomenally_ complex system that don’t manage to produce projections that match measured reality and 14 excuses are then forwarded to explain why they don’t, each one claiming to completely explain away the problem, then it’s rather obvious to anyone that those attempting to model that complex system really don’t have a adequate handle on the factors involved in it. Isn’t it?
katatetorihanzo on July 24, 2014 at 10:15 am
What strips your story of credibility is that it is always changing. Like climate does.
Some of us remember when the recent warming up-oscillation was still going strong. The idea of natural climate variation was openly derided by on-a-roll warmists. The very word “natural” was a dirty word. Any empirical observation of climate history was dismissed as worthless in the face of unquestionable authority of climate models.
Times change. Now the warmists are crawling all over natural variation. With every twist and turn in the real world a new story quickly appears to explain it. And the party line changes as quickly and frequently as the weather itself.
What would have given this any credibility is if any of this had been predicted by your models. The pause. Antarctic and now Arctic sea ice recovery. Decline in sea level rise. Increased snow cover. But no – it’s all post hoc, after the event. I’m afraid it doesn’t wash.
dbstealey says:
July 24, 2014 at 11:10 am
hanzo says:
Now it’s time for all of us to get on the same page and determine how to adapt to and mitigate an ever increasing economic disruption due to climate change.
Hanzo is feeding at the taxpayer gravy trough, so naturally he wants the loot flow to continue. But there is nothing that anyone needs to do. As I pointed out above:
The null hypothesis is the statistical hypothesis that states that there are no differences between observed and expected data. And since there are no differences between what is currently being observed and what happened in the past, the null hypothesis is not falsified. Global warming is natural.
Which as I’ve pointed out before is not the ‘null hypothesis’ and you conveniently forget about it when you want to claim that there is global cooling.
The null hypothesis has never been falsified. It is a direct corollary of the scientific method, and it shows that there is nothing happening that is either unusual or unprecedented. Therefore, nothing needs to be done.
What you claim to be the ‘null hypothesis’ bears no resemblance to the scientific method.
Phil.,
I’ve given you the dictionary definition of the null hypothesis several times. It’s not my fault that you can’t understand it.
Also, the null hypothesis is not the scientific method. Show me where I said it was. It is a corollary.
The null hypothesis applies to any research question, no matter what the debate is or who is on which side. For example, if your speculation is that dust is not natural, the null hypothesis would be that it is. The null hypothesis simply forces you to seek significant robust results against the premise that your speculation is not significant.
In summary, when engaged in formal climate research, for any who propose that temperature trends are human caused, they must be willing to admit that the null hypothesis is that temperature trends are natural. The flip side would be that for those who propose that temperature trends are natural, they must be willing to admit that the null hypothesis is that temperature trends are human-caused.