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.
—————————-
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:
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Once again we are assured that natural variation is strong enough that the negative swings can cancel out global warming. On the other hand, the positive natural variation swings have absolutely no impact on global warming, it’s all CO2.
If there is a linear increase in GISS from adjustments as suggested by Goddard and Lovejoy’s natural variability theory is valid, then would this prove no CO2 warming?
Lovejoy has committed a no-no here. If the pause or cooling is a natural variation, perhaps too was the warming.
I’m sure The Team will be knocking on his door.
So, instead of the heat “hiding”, they are now claiming it is being masked by a natural variation.
Interesting.
It’s there, but we can’t see it.
Sort of like people who claim to see ghosts.
They see dead warming.
All this talk about NATURAL VARIATION masking the warming effects of green house gases is just another way of saying Natural Variation dwarfs the effects of green house gases or. greenhouse gases are a minor player compared to natural variation in shaping the climate of this planet.. ” It is worse than we thought”, we got it totally wrong from day one .
Goldie says:
July 21, 2014 at 7:13 pm
Now that the models are in forecast mode they are proving to be more and more inaccurate. I suggest we develop some new models that fit the current hind-cast and then see how they look going forwards. In other words; throw away the old models, figure out what was missing, add that in and then start again.
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.
Already done, see for example:
Grant Foster and Stefan Rahmstorf 2011 Environ. Res. Lett. 6 044022 doi:10.1088/1748-9326/6/4/044022
Unfortunately some of those factors are random or chaotic in nature so they are hard to incorporate in a model.
However, see the following where ENSO was incorporated into the model:
Yu Kosaka & Shang-Ping Xie, Nature 501, 403–407 (19 September 2013) doi:10.1038/nature12534
Who ya gonna believe?
Phil.?
Or the real world?
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.
Hey, and what about our wager? Are we on? ☺
Lovejoy is closer to my thinking if he also means that the warming period got a 1/3 C assist with this natural variation wave.
The smart climate scientists are not distracted by all the hype about greenhouse gasses causing global warming . This is just a political diversion created to extract more tax money from the public . It is not based on sound science. This flawed climate science seems to use exaggerations or worst case scenarios that may never come about to make their quite flawed case. The smart scientists are deeply focused on natural variation of the oceans and more particularly the great ocean conveyor belt. There is a real concern that the current 17 year pause in the rise of global temperatures will turn out to be at least 30 years of cooler climate and possibly all the way to 2100 as there may be at least two cool cycles before 2100 based on the natural variability of the oceans . The clue is in the continued cooling of the southern oceans around the Antarctic and the start of the cooling of the Northern Hemisphere and North Atlantic Keep an eye on the Atlantic Ocean and its currents . I believe Professor William Gray’s studies will come into new prominence and acceptance , in my opinion. I see this awareness of the possible changes to the ocean conveyor belt coming under closer general public debate during the next 2-3 years as the global temperature hiatus stretches to 20 years and the Atlantic Ocean continues to cool
Earth’s Magnetic Field Flip Could Happen Sooner Than Expected (9 Jul 14)
“Changes measured by the Swarm satellite show that our magnetic field is weakening 10 times faster than originally predicted, especially over the Western Hemisphere.”
http://www.scientificamerican.com/article/earth-s-magnetic-field-flip-could-happen-sooner-than-expected/
Found to be not 5% per century, but 5% per DECADE.
——
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
“The increase in atmospheric CO2 concentration has been thought to be the main cause of climatic changes at these high altitudes. This study suggests that magnetic field changes that have taken place over the past century are as important.”
——
New paper finds Medieval Warm Period was global & significantly warmer than the present, rejects Mann’s hockey stick
http://hockeyschtick.blogspot.com/2014/07/new-paper-finds-medieval-warm-period.html
I don’t understand why so many people have trouble understanding the difference between “being warm” and “warming”. We have warmed slightly (a fraction of a degree GMT) which makes warm records, however, we haven’t warmed further for the last ~18 yrs. Why do so many, find this, so hard to grasp? GK
Exposed: The myth of the global warming ‘pause’
http://www.independent.co.uk/environment/climate-change/exposed-the-myth-of-the-global-warming-pause-8945607.html
That’s just one of many. How many different excuses for the pause have they come up with, each one claimed to be the sole factor behind the pause? That alone tells me they haven’t a clue.
In logical form, the Independent’s argument is an equivocation in which the meaning of “global temperature” changes in the midst of this argument. By logical rule, one cannot draw a proper conclusion from an equivocation. Nonetheless, the Independent draws the conclusion that the ‘pause’ is a myth.
“The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence.”
Huh?
And here I thought that the Warmologogical gospel was that “manmade warming” didn’t actually begin until about 1980. Now it’s the entire “industrial epoch”? They are claiming manmade warming has been going on for 250 years? Seriously? And with 99.9% confidence? Holy cow!
They have truly lost the plot.
“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””
And yet, periodic and relatively lengthy (relative to the 50 year upswing in temps) was completely ignored in the model predictions of calamitous temperature increases. So, once you factor this periodic natural cooling swing in, the projected increase is only 1/3 to 1/2 of what the models predict over say a 100 year span?
Should be a standard rule of academia – show your hypothesis; make a falsifyable prediction; bet half your pension against it…otherwise, f@ck off.
dbstealey says:
July 22, 2014 at 7:12 am
Who ya gonna believe?
Phil.?
Or the real world?
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.
As usual you have mis-stated the null hypothesis. When looking at a set of data such as you presented your hypothesis was that it showed global cooling, the null hypothesis is that there has been no change over that timespan. Statistical analysis of that data shows that the null hypothesis has not been falsified and that there has been no significant cooling.
Hey, and what about our wager? Are we on? ☺
I don’t bet so there is no wager.
I’m a simple layman trying to follow the ‘debate’ regarding the ‘pause’ (and a pause means to me that something that was happening has stopped but will start again). I am having trouble with this notion of natural variability. We are debating the planet’s climate. But surely it cannot change in some random way for no reason – but only through the interaction of the various drivers. If the actual observed data is at variance with the models’ predictions, then does that mean that they do not take account of those drivers and their interactions? It might seem that ‘natural variability’ includes all those other factors that are not addressed by the models. Is this because the modellers don’t know either what they are; how they interact; or how to include them?
steve s:
“Natural variability” is a component of a bad argument that is made by the IPCC in its assessment reports. IPCC climatologists borrow an idea from telecommunications engineering in which the intensity of the received signal is the sum of the intensity of the transmitted signal and the intensity of the noise. Supposedly, the natural variability is akin to the noise. There is an additional component of the global temperature that is caused by emissions of CO2 from burning fossil fuels. This component is called the “anthopogenic signal.” IPCC climatologists claim to detect the anthopogenic signal with a high level of statistical confidence, thus pinning the blame for global warming on the burning of fossil fuels.
The solution that evironmentalists propose for this state of affairs is to control the climate through curbs on CO2 emissions. However, there is an assymmetry between telecommunications engineering and control systems engineering that is not taken into account by the IPCC’s argument. In telecommunications, the signal and noise travel from the present toward the future at a speed that cannot exceed the speed of light. In control, the “signal” and “noise” would have to travel from the future to the present at a speed exceeding the speed of light but this is impossible under the theory of relativity. In relation to the problem of controlling the climate, there can be no signal or noise. That these entities exist is, however, built into the structure of modern global warming climatology. In order for progress to be made in global warming climatology, wrenching changes must be made in the structure of it.
What precisely are the components of a “natural cooling fluctuation”?
And how were they able to overwhelm, the global destruction, by the enemies of nature?
Tune in next week (month) for another adventure in, “We know best, so pay up, and shut up”!!
The simplest explanation, is that increasing levels of CO2, are not able to increase levels of water vapor, except in very dry arctic conditions. We have a low climate sensitivity, to additional CO2.
So we have a tiny increase in temps, that are masked by natural variations, that are an order of magnitude larger. The increasing trend has stopped, and may resume, or may reverse. Time will tell. But one thing is for certain. There will be many more attempts, to revive a corpse, that is more skeleton, than flesh.
peakweather says:
July 22, 2014 at 12:52 am
every year on Jan 1st for the last 10 years, the BBC have stated that the previous year was the warmest on record
Here are the top 10 on Hadcrut4:
1 {2010, 0.547},
2 {2005, 0.539},
3 {1998, 0.531},
4 {2003, 0.503},
5 {2006, 0.495},
6 {2009, 0.494},
7 {2002, 0.492},
8 2013 0.486
9 {2007, 0.483}
10 2012 0.448,
However Hadcrut4 is very recent and 10 years ago, they had Hadcrut3. Here are the top 10 on Hadcrut3:
1 {1998, 0.548},
2 {2005, 0.482},
3 {2010, 0.478},
4 {2003, 0.475},
5 {2002, 0.465},
6 2013 0.461
7 {2004, 0.447},
8 {2009, 0.443},
9 {2006, 0.425},
10 {2001, 0.408}
So going by Hadcrut3, that statement should not have been made since 1998.
The problem with much of these theories is that the Alarmists in government and academia were still in full-blown AGW mode as late as 2007. That means everything that wrote and said between 1996-98 and 2009 (when they first grudgingly admitted to the “pause”) was either known fabrication or simple scientific incompetence.
I can still remember (and I’m sure still find via the Wayback Machine) highly respected and credentialed scientists saying in 2006 how the current warming was absolutely unprecedented for the Holocene Era. NOAA was publishing warnings about the run-away heat waves, historically warm winters (The 3rd Warmest January Ever!!!!, etc..), and the tropical storms that would be making landfall in record numbers, etc….
But, now we are supposed to forget about all those Cassandra-like warnings, and still listen to the Alarmists. I think not.
The null hypothesis is that both warming and cooling are natural. That is all. It doesn’t say anything about what our climate is currently doing. We do though appear to be cooling, and cooling is likely in the coming decades.
So natural variation is not strong enough to cause global warming but it is strong enough to negate global warming. Sounds a little fishy to me.
It seems that all the paper has done is show that there has been a long term warming trend in addition to the 20 to 30 years cyclical variations. But part of the long term trend can also be caused by natural forces that are different from the shorter term ones, and not necessarily caused by CO2. His equation (1) seems to indicate he is considering only one type of natural variation.
Equivalent version of basic equation:
T(globe) = T(CO2) + T(natural)
See, take away the cooling and what’s left? 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,””
The way I see it is that declines in solar forcing from 1995 promoted a warm AMO phase, an amplified negative feedback, raising global mean surface temperatures around 0.2°C by poleward heat redistribution alone. 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.