UPDATE: a response to this paper has been posted, see below.
From McGill University , who blows the credibility of their science by putting the word “deniers” in it.
Statistical analysis rules out natural-warming hypothesis with more than 99 percent certainty
An analysis of temperature data since 1500 all but rules out the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate, according to a new study by McGill University physics professor Shaun Lovejoy.
The study, published online April 6 in the journal Climate Dynamics, represents a new approach to the question of whether global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels. Rather than using complex computer models to estimate the effects of greenhouse-gas emissions, Lovejoy examines historical data to assess the competing hypothesis: that warming over the past century is due to natural long-term variations in temperature.
“This study will be a blow to any remaining climate-change deniers,” Lovejoy says. “Their two most convincing arguments – that the warming is natural in origin, and that the computer models are wrong – are either directly contradicted by this analysis, or simply do not apply to it.”
Lovejoy’s study applies statistical methodology to determine the probability that global warming since 1880 is due to natural variability. His conclusion: the natural-warming hypothesis may be ruled out “with confidence levels great than 99%, and most likely greater than 99.9%.”
To assess the natural variability before much human interference, the new study uses “multi-proxy climate reconstructions” developed by scientists in recent years to estimate historical temperatures, as well as fluctuation-analysis techniques from nonlinear geophysics. The climate reconstructions take into account a variety of gauges found in nature, such as tree rings, ice cores, and lake sediments. And the fluctuation-analysis techniques make it possible to understand the temperature variations over wide ranges of time scales.
For the industrial era, Lovejoy’s analysis uses carbon-dioxide from the burning of fossil fuels as a proxy for all man-made climate influences – a simplification justified by the tight relationship between global economic activity and the emission of greenhouse gases and particulate pollution, he says. “This allows the new approach to implicitly include the cooling effects of particulate pollution that are still poorly quantified in computer models,” he adds.
While his new study makes no use of the huge computer models commonly used by scientists to estimate the magnitude of future climate change, Lovejoy’s findings effectively complement those of the International Panel on Climate Change (IPCC), he says. His study predicts, with 95% confidence, that a doubling of carbon-dioxide levels in the atmosphere would cause the climate to warm by between 2.5 and 4.2 degrees Celsius. That range is more precise than – but in line with — the IPCC’s prediction that temperatures would rise by 1.5 to 4.5 degrees Celsius if CO2 concentrations double.
“We’ve had a fluctuation in average temperature that’s just huge since 1880 – on the order of about 0.9 degrees Celsius,” Lovejoy says. “This study shows that the odds of that being caused by natural fluctuations are less than one in a hundred and are likely to be less than one in a thousand.
“While the statistical rejection of a hypothesis can’t generally be used to conclude the truth of any specific alternative, in many cases – including this one – the rejection of one greatly enhances the credibility of the other.”
“Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming”, S. Lovejoy, Climate Change, published online April 6, 2014. http://link.springer.com/search?query=10.1007%2Fs00382-014-2128-2
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Christopher Monckton has posted a rebuttal to this paper, see here
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The analysis described in the paper only applies for natural variation behaving like Brownian motion. As far as I know no-one has ever claimed that natural processes are stochastic. Instead natural variation is proposed to be cyclic with time periods of 60 years and larger. His paper does not address this hypothesis at all. Instead the “research” reproduces high school physics showing that the probability of a dust particle in a gas following a path similar to the anomaly data is very small.
I don’t see any new insights at all in this paper.
“This study will be a blow to any remaining climate-change deniers,” Lovejoy says
Correction: should read “This study is not likely to stem the growing number of climate change sceptics”
And the whole proposition is founded upon CO2 having the attributes the alarmists side claims, however if CO2 is not the climate driver it is theorised to be then the entire proposition is built on a foundation of quicksand. If CO2 is the result of natural cyclic warming and not the primary cause then this paper is just so much junk to be added to the gigantic pile of CAGW trash. These people are going to look very silly and many are going to bitterly regret the work they do now.
BTW, what global warming? Doesn’t he know that even Mann recognizes the so-called ” Pause” (i.e. no warming).
“We’ve had a fluctuation in average temperature that’s just huge since 1880 – on the order of about 0.9 degrees Celsius,” Lovejoy says. “This study shows that the odds of that being caused by natural fluctuations are less than one in a hundred and are likely to be less than one in a thousand.”
Baseless statement. Good global thermometer records dates back to 1880. How can Lovejoy say the fluctuation is big or small by just looking at one data set? Big or small compared to what? Older temperature fluctuations? But these are tree rings and ice cores. Not comparable to the resolution of thermometers. The odds cited are meaningless. The said “fluctuations” follow the normal distribution which is true of random variables. In short, the fluctuations look random. The challenge is to prove they are not.
“His study predicts, with 95% confidence, that a doubling of carbon-dioxide levels in the atmosphere would cause the climate to warm by between 2.5 and 4.2 degrees Celsius.”
Since this statement is based on computer models, what it really means is the models output 2.5-4.2 C 95% of the runs. It doesn’t tell us anything about reality since all the models could be wrong. They can even output wrong temperatures 100% of the runs.
Since Lovejoy says he didn’t use huge computer models, maybe he used excel spreadsheet or manual calculations. It doesn’t matter. To assert 95% confidence he must have data generated from calculations by computer or by hand. Paleoclimate empirical data will not give 95% confidence since temperatures and CO2 varied widely in the past 600 million years.
Well as the data shows that the global temperature figures are made up of short term cycles that have an approximate +-0.2c range over periods of 12 months to ~60 years and just those two accounts for the majority of the variation in the data to date the data alone refutes this suggestion.
http://climatedatablog.files.wordpress.com/2014/04/mar-2014-uah-global.png
AGW since 1880? Or since 1979?
It’s funny how they switch and choose when it suits them!
“Jupiter did it: changed the Earth’s orbit just enough.”
Leif, it’d be great if you would do one of your very good .ppt’s on that. It’s worrying that Jupiter can throw planet Earth around that much, good job we got moved nearer the sun instead of further away.
Or perhaps Leif missed the /sarc tag off the end of his comment.
His hypothesis is that the global temperature is given by the following function Tg = Tanth + Tnat + eps, where Tanth is the anthropogenic CO2, Tnat is a stochastic natural variation, and eps is an error term. He assumes that Tanth is the ONLY deterministic, i.e. non-random, variable in the time period. In fact there are several deterministic variables involved in natural variability over these time frames in the sense that such variables as solar index, land use, etc are not stochastic, but deterministic functions of time. By that I mean that if one tested to see if solar index for example was stochastic over this time interval one would find a strong indication that it was not. If he had included a few other climate variables he would have found that indeed they also were strongly correlated to the global temperature. To his chagrin, he would also have found (if he had looked) that all of the climate variables are correlated strongly with each other and that by using various subsets of them his correlation constants would have bounced around hopelessly as the remaining variables incorporated effects of the deleted variables. Climate is a classical case in which statistics is difficult due to cross correlation of virtually all variables of interest.
So if we restate his hypothesis: If one tests whether global temperature over a time period varies randomly over that period or whether it is correlated with one of a set of cross correlated climate variables that change non randomly over that time period, then one should find that any climate variable does better than the random assumption. A much more honest appraisal would have been to include a few other deterministic variables from the climate set such as solar cycle, TSI, land use, ice cover, the temperature of the martian landscape, etc. and do the same analysis. It is guaranteed that the same test would find that virtually any individual non-random climate variable would do better compared to the assumption that the climate varies randomly. It is also guaranteed that it would be impossible to argue statistically that any particular subset of the climate variables was preferred over another since they are all strongly cross correlated.
This is yet another example of the need to expose physical scientists to much more classical statistics, even better, for them to work closely with one or two pure statisticians whose areas of work cover a broad range of data analysis, not just trying to find a way to prove something one already believes.
Magma (April 11, 2014 at 7:48 pm) “A list of some of Lovejoy’s ~500 publications since 1981:…”
For a list of 491 postings by the troll Magma on WUWT, Google: site:wattsupwiththat.com magma -volcanoes
Is that McGill University or McGoo University?
Dr. Lovejoy starts with the assumption that global warming is either natural or man-made and is not a combination of the two. This assumption suffers from major bogusness.
As the global temperature continues to plummet any theory on global temperature must explain both rising and falling temperatures. Assuming the global temperature is controlled solely by CO2 does not meet this criterion.
Wow! What an amazing result! I can hardly wait for Dr. Lovejoy’s follow up paper where he refines his statistics and rules out natural variation with a greater than 342% confidence level. Excelsior!
🙂
I guess they missed the April 1st deadline for this one.
I’m pretty sure that even most “consensus” climate scientists will wince.
““We’ve had a fluctuation in average temperature that’s just huge since 1880 – on the order of about 0.9 degrees Celsius,” Lovejoy says. “This study shows that the odds of that being caused by natural fluctuations are less than one in a hundred and are likely to be less than one in a thousand.”
Oh. So he’s one of the last remaining MBH 98 defenders and claims that the climate was eternally stable before the combustion engine.
No Roman Warm Period, no MWP, no holocene climate optimum.
He probably does not believe in Marcotte & Shakuns temperature reconstruction either.
How is this guy at a university?
Space Aliens must have created the Younger Dryas, McGill university researchers leave as only logical explanation.
Onset of glaciations too fast to be natural, McGill finds out.
WHO ICED OVER THE PLANET? Film at 11.
Did anyone ask them what global warming?
Because how can one deny something that instrumentally isn’t happening in the data?
Maybe they meant denial of CO2 rise?
Do we have any CO2 rise deniers?
“We’ve had a fluctuation in average temperature that’s just huge since 1880 – on the order of about 0.9 degrees Celsius,” Lovejoy says.
0.9 degrees in 134 years – wow.
Frank Lansner did a chart on that a while back.
http://www.rockyhigh66.org/stuff/rate_interglacial_temps.png
I got stuck on Fig. 5, where the authors purport to show that the global trends in three contiguous past 125-year intervals were minimal, whereas that in the 125 years just ending was significant.
If you look at the Central England index, you do indeed find a high trend (~0.9 deg./ century) for the most-recent 125 years. Since that trend is less then twice that (instrumental) index’s trend (~0.5 deg./ century) for the 125-year period that ended in 1796, though, I think we can be forgiven for questioning the authors’ (proxy-based) conclusion that the pre-industrial era lacked significant secular trends–or the corollary that man caused most of the recent trend.
““This study shows that the odds of that being caused by natural fluctuations are less than one in a hundred and are likely to be less than one in a thousand.”
That’s about right. One part in a thousand is roughly the length of the instrumental temperature record compared to a total glacial-interglacial cycle.
But the surface temperature standstill is natural?
I maybe mistaken but I thought the IPCC never attributed man’s greenhouse causing most of the 1910 to 1940 warming.
Ok fine. Then where’s the heat been hiding for nearly the last 2 decades? Idiots.