Guest post by David Middleton
From the BBC…
Climate: Cherries are not the only fruit
Just about the most predictable event of the week was the tempest of opinion created by the analysis of global temperature changes published in the Proceedings of the National Academy of Sciences (PNAS) on Monday.
As we (and a number of other mainstream news outlets) reported, Robert Kaufmann and colleagues analysed the impact of growing coal use, particularly in China, and the cooling effect of the sulphate aerosol particles emitted into the atmosphere.
They concluded that with a bit of help from changes in solar output and natural climatic cycles such as the El Nino Southern Oscillation (ENSO), the growth in the volume of aerosols being pumped up power station chimneys was probably enough to block the warming effect of rising greenhouse gas emissions over the period 1998-2008.
For some commentators, such as the UK Daily Mail’s Christopher Brooker, this was further proof that the “climate scaremongers” had got it wrong…
[…]
Cherry in the pie
One thing that everyone in the climate blogosphere seems to agree on is that the best fruit in the world is the cherry, judging by the number that are picked.
And the Kaufmann paper has brought a few more down from the tree.
The Global Warming Policy Foundation (GPWF), the UK-based pressure group, said researchers “tweak an out-of-date computer model and cherry-pick the outcome to get their desired result”.
To which the opponents’ rejoinder is, and long had been: “well, choosing 1998 as the baseline is cherry-picking, to start with”.
To illustrate the point, I’ve been through a quick exercise using the approach that groups such as GPWF favour – and that Kaufmann’s research group adopted – of using annual temperatures rather than any kind of smoothed average, and looking for the temperature change over a decade.
I took the record of global temperatures maintained by Nasa’s Goddard Institute for Space Studies (GISS) which is one of the three main global datasets, and calculated the rate of change over each of the most recent 10 decades – ie, 1991-2001, 1992-2002, and so on up to 2000-2010.
I’ve summarised the results in a table on this page. What it basically shows is two things:
- the numbers vary quite a bit from year to year; and
- all but one give a temperature rise – the only one that shows a small drop being 1998-2008.
Seeing as it’s logically impossible that the world warmed between 1997 and 2007, cooled between 1998 and 2008, and warmed again from 1999 to 2009, one conclusion you might reach is that using annual temperatures is not a sensible thing to do as it gives you a set of answers that does not make sense.
… which is why most scientists use the running mean approach.
[…]
Mr. Black seems to be suggesting that Figure 3 from Kaufmann is a cherry being picked by climate realists…
While he thinks that GISTEMP is the “tree”…
Well, I say that Mr. Black is Goldilocks-picking. Mr. Black asserts that it is cherry-picking to use 1998 as a starting point and that the starting point must be 1880. What’s so special about 1880 (apart from it being the start of the instrumental record)?
First off, let’s have a look at a few “cherries.”
Here is the HadCRUT3 global temperature anomaly (GTA) for 1977-2010 plotted with the GTA for 1911-1944…
HadCRUT3 Global Temperature Anomaly 1911-1944 & 1977-2010
Here’s the HadCRUT3 Northern Hemisphere temperature anomaly for 1976-2010 plotted with a non-carbonated interval from the Medieval Warm Period (Moberg et al., 2005)…
HadCRUT3 Northern Hemisphere 1976-2010 & Moberg 863-897
In both examples, the slopes are statistically indistinguishable.
The 66-yr period from 1944-2010 is pretty well indistinguishable from the first 66 years of three different century-scale cool-warm-cool cycles from Moberg’s Medieval Warm Period reconstruction…
HadCRUT3 global 1944-2010 & Moberg NH 831-930, 961-1050, 1038-1138 (Yes, I know I should have used HadCRUT3 NH… I just don’t have a display handy).
The peak of the Modern Warming is, at most, 0.1 to 0.2°C warmer than the peaks of three comparable, non-carbonated, intervals of the Medieval Warm Period, consistent with a net climate sensitivity of ~0.5°C. However, that difference is probably not statistically meaningful.
- The error bars of all of the data sets are greater than the differences between them.
- The proxy data show the MWP to be warmer than the late 20th century.
- The proxies invariably have a lower resolution than the instrumental data; thus the amplitude of the proxy time series is attenuated relative to the instrumental record.
This means that the late 20th century warming might have been slightly warmer than the peak of the MWP. Almost all of the potential error is in the direction of magnifying the warmth of the Modern Warming relative to the MWP, so the odds are that the modern warming is very comparable to the Medieval Warm Period.
Since Mr. Black would probably say that the Medieval Warm Period is another “cherry,” let’s go back another 1,000 years, or so.
What happens if I project the polynomial trend-line a few hundred years into the future?
It starts looking like a cyclical pattern doesn’t it?
One of the “problems” with the way climate data are handled is in the obsession with applying linear trend lines to non-linear data.
A Sine wave has no secular trend…
But… What happens if my data represent only a portion of a Sine wave pattern?
The r-squared of a linear trend line of this partial Sine wave is 0.88… 88% of the data fit the trend line. This implies a very strong secular trend; yet, we know that in reality Sine waves do not have secular trends.
If we take the entire HadCRUT3 series and apply a linear trend line, we get an apparent secular trend…
The r-squared is 0.55… 55% of the data fit the secular trend. This implies that there is a real long-term warming trend.
What happens to that secular trend if we expand our time series like we did with the Sine wave?
The apparent secular trend vanishes in a puff of mathematics…
How can such a clear secular trend vanish like that? The answer is easy. Each “up hill” and each “down hill” leg of a Sine wave has a very strong secular trend. Unless you have enough data to see several cycles, you don’t know if you are looking at a long-term trend or an incomplete cycle.
Using the GISP2 ice core data from central Greenland we can see that over the last 50,000 years, there have been statistically significant warming trends…
And there have been cooling trends of varying statistical significance…
What does all of this mean?
It means that the Earth’s climate is cyclical. It means that the climate changes we’ve experienced over the last 150 years are not anomalous in any way, shape, fashion or form. And it means that the Mr. Black and the other warmists must “Goldilocks-Pick” their data. Too short of a time series yields no warming trend and too long of a time series also yields no warming trend. The time series must be “just right” in order to show an anomalous warming trend.
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Here’s a cherry on on a snow cone: http://www.flatheadbeacon.com/articles/article/ultra-marathon_race_cancelled_due_to_snow/23833/
This is a very poor analysis. A lot of timeseries tend to go up and then down and then up (eg the price of gold). You can’t just assume it’s a cycle.
If manmade global warming is true the temperature is going to keep rising, irregardless of past changes and whether you can fit them with various curves.
So working backwards and saying because the warming so far can be fit with curves or isn’t beyond magnitudes of past warming is illogical and bears nothing on what Richard Black was saying.
My own belief is that looking at decadal temperature changes is the new trick to hide the lack of warming. (In the IPCC AR4, you will remember that is was to state the number of record years.)
The other question to ask is why a reporter for the UK taxpayer-funded BBC should use foreign data over the UK taxpayer-funded Hadley centre. An analysis of the figures will show why – NASA GISSTEMP shows a warming trend since 2000, whereas HADCRUT3 does not. Black’s peculiar choice seems to be based on choosing the data series that best fits his story.
I have posted a couple of graphs which demonstrate this bias.
http://manicbeancounter.wordpress.com/2011/07/11/show-warming-after-it-has-stopped-part-2/
nomnom says:
July 11, 2011 at 3:54 pm
So working backwards and saying because the warming so far can be fit with curves
===============================================================
That’s exactly right……
….the climate computer games are illogical
I will admit to having often wondered how much the early 20th century temp increase was due to moving away from unfiltered wood/coal burning for household heating in the developed world, and thus giving an inappropriately larger delta to the temp increase for the period. And then again in the 80s-90s as clean air regs toughened and the dirty old Soviet Union/East Euro industries tanked.
The extreme AGW proponents either ignore or are unaware of the cyclic warming and cooling of the planet that correlate with solar magnetic cycle changes. (The solar magnetic cycle changes cause an increase or decrease to the solar heliosphere and solar wind which in turn results in an increase or decrease in atmospheric ionization which in turn results in less or more low level clouds which results in more or less solar energy being reflected into space.)
The following is a review paper that discusses the mechanism and observational data that supports the mechanism by which solar magnetic cycle changes results planetary climate change.
Atmospheric Ionization and Clouds as Links between Solar Activity and Climate
By Brian Tinsley and Fangqun Yu
http://www.utdallas.edu/physics/pdf/Atmos_060302.pdf
Overall, clouds reflect more solar radiation than they trap, leading to a net cooling of
~27.7 W/m2 from the mean global cloud cover of ~63.3% [Hartmann, 1993].
There are a number of paleoclimatic papers that note there is correlation with C14 and other cosmogenic isotopes changes gradual and abrupt climatic change. For example Gerald Bond’s Persistent Solar Influence on North Atlantic Climate during the Holocene which is one of a series of papers written by Bond that tracked the correlation of levels of the cosmogenic isotopes C14 and Be10 with centennial to millennial climate change.
http://www.essc.psu.edu/essc_web/seminars/spring2006/Mar1/Bond%20et%20al%202001.pdf
…The evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon-14 and beryllium-10 and centennial to millennial time scale changes in proxies of drift ice measured in deep-sea sediment cores. A solar forcing mechanism therefore may underlie at least the Holocene segment of the North Atlantic’s 1500-year cycle…
Another example is this paper which discusses the cause of the Younger Dryas abrupt climatic change which interrupted the current Holocene interglacial returning the planet back to the glacial phase.
“Reduced solar activity as a trigger for the start of the Younger Dryas?”
http://www.geo.vu.nl/~renh/pdf/Renssen-etal-QI-2000.pdf
From the paper:
“Estimates for the start of the YD all demonstrate a strong and rapid rise of C14 (Cosmogenic isotope that increases when there is decreased solar activity that hence allows increased galactic cosmic rays GCR to strike and interact with the atmosphere.) This change is the largest increase of atmospheric C14 known from the late glacial period and Holocene records.”
http://cc.oulu.fi/~usoskin/personal/Miyahara_AG06.pdf
The Solar Cycle at Maunder Minimum Epoch
The Maunder minimum is considered as an example of occasionally occurring Grand minima, when the solar dynamo was in a special mode. We review available sets of direct and indirect data covering the period during and around the Maunder minimum. The start of the minimum was very abrupt and was followed by a gradual recovery of the activity. The data suggest that while the sunspot activity was greatly suppressed during the deep phase of the minimum, the cyclic dynamo kept working around the sunspot formation threshold level, leading to seemingly sporadic occurrence of sunspots.
Cosmogenic isotopes are produced in the Earth’s atmosphere mainly by galactic cosmic rays, which originate from outside of the heliosphere and are modulated by the solar wind and interplanetary magnetic field. The basics of the modulation process are well understood (see, e.g., Refs. 20 and 21), and the attenuation level of cosmic rays in the heliosphere depends on the strength and level of turbulence of solar magnetic field and on the global structure of the heliosphere. Basically, the flux of cosmic rays impinging on the Earth is inversely correlated with the solar activity, but shows also variations depending on, for example, the polarity of solar magnetic field.
Cosmogenic isotopes provide the most extendable indirect data on the cosmic ray flux, the state of the heliosphere, and hence on the solar magnetic activity during the past. The most commonly used cosmogenic isotopes are radiocarbon (i.e., 14C) and 10Be, which are measured in tree-rings and in ice cores, respectively. Both tree-rings and ice cores form stratified structures and retain the time variations of the abundance of isotopes in each layer.
14C and 10Be are produced in the atmosphere as a result of nuclear reactions of cosmic rays with the atmospheric nuclei. Then 14C is oxidized to form carbon dioxide and circulates within the carbon cycle between different reservoirs, some of which are very inertial, and it gets eventually absorbed by trees by means of photosynthesis. On the other hand, 10Be becomes attached to aerosols, precipitates with snowfall and is accumulated in the ice in polar regions.
Another example is this paper which discusses the cause of the Younger Dryas abrupt climatic change which interrupted the current Holocene interglacial returning the planet back to the glacial phase.
“Reduced solar activity as a trigger for the start of the Younger Dryas?”
http://www.geo.vu.nl/~renh/pdf/Renssen-etal-QI-2000.pdf
From the paper:
“Estimates for the start of the YD all demonstrate a strong and rapid rise of C14 (Cosmogenic isotope that increases when there is decreased solar activity that hence allows increased galactic cosmic rays GCR to strike and interact with the atmosphere.) This change is the largest increase of atmospheric C14 known from the late glacial period and Holocene records.”
Pretty impressive looking analysis.
I still think, despite the ‘consensus’, that late 20th century warming was mostly from the sun, c02 having a very small role, why? the slope is the same as when we know its was the sun without any c02-like in MWP. Late 20th century warming is just a heat time lag from increased solar output from ~1750-1950, like the ~6 weeks after the summer solstice when when T continues to rise, despite the decreasing solar rays “going in opposite directions” to the continued warming.
Truth will out, but this is a very good anaylysis above.
http://www.fao.org/docrep/005/y2787e/y2787e06.htm
5. LONG-TERM AND SHORT-TERM TIME SERIES OF GLOBAL CLIMATIC INDICES AND FISH STOCK
The most pronounced spectral maximum of the long-term fluctuations for all “long-term” time series (excluding anchovy) varies within the interval of 54-58 years. The corresponding climate cycles (both measured and reconstructed) vary within the range of 50-65 years (in average, 56 years).
“All these things have causes, and for some of the warming that has occurred in the later part of the 20th and into the 21st century, when all other known factors are excluded, including solar cycles, (yes, solar cycles have long been known to affect temperatures) the only known factor that remains is the anthropogenic fingerprint of greenhouse gas increases.
Might there be some other, as yet unidentfied, cause? Absolutely! And if there is, it is only through the hard work of climate research that it will be discovered and quantified.”
The Argument from Ignorance, writ large. “The only known factor”, indeed.
Bart says:
July 11, 2011 at 1:15 pm
The distinction is important because, the first argument you will get against the idea is that there is no known forcing with a ~60 year period.
That’s because Climate Science is married to CO2.and is not allowed out of the house on their own.
Jupiter and Saturn have a 60 year orbital harmonic (12 and 30 years). Over time, even a very small cyclical forcing will have a large effect if any of the systems on earth resonant at the same frequency. Earth’s tides for example, are much larger than can be explained by simple linear forcings.
All objects have resonant frequencies and the larger the object the longer the period. Until the natural frequency(s) of the earth’s climate systems is known, it cannot be ruled out that there is a 60 year natural harmonic. Given the age of the earth and solar system, nature has had a very long time to shape the earth and oceans to match the cyclical forcings of the heavens.
The notion that something doesn’t exist because we haven’t found it only makes sense in the case of objects that are unlikely. There is nothing unlikely about cyclical natural behavior, including climate cycles. What is unlikely is non cyclical behavior. What should be assumed is that no event in nature is non cyclical until proven otherwise.
Anna Lemma says:
July 11, 2011 at 10:01 pm
The Argument from Ignorance, writ large. “The only known factor”, indeed.
Exactly. Science routinely demonstrates that the set of things we don’t know about any subject is larger than the set of things we do know. Climate science is like an adolescent child thinking they know it all, because they have no idea of how much there is yet to learn.
I get the impression that statistics in climatology is meaningless not only does it not solve the problem it can’t even eliminate anything.We are told we are cherry picking however we look at these statistics.It could be that what we need is a better understanding of how the Earth’s climate works before statistics could be any use.
nicola scafetta says:
July 11, 2011 at 11:13 am
Dear Vukcevic,
a quasi 60-year cycle in the climate has been observed by a lot of people in a lot of climate records..
Dr. Scafetta
Thank you for your note. I am fairly familiar with harmonic and quasi-harmonic oscillations and the cross-modulation products. When Dr. Hathaway of NASA was predicting largest solar cycle, I published this
http://www.vukcevic.talktalk.net/NFC7.htm
and subsequently was declared ‘cyclomaniac in supreme’ by couple of other solar scientist.
I have also travelled down the ‘climate cycle’ road (see last graph in: http://www.vukcevic.talktalk.net/SSA.htm ) but eventually realism prevailed.
To N. Scafetta.
I read your paper on Climate change causes and its prtty much the same as what I have been coming to over hte last 3-4 years.
Variations in 20th century trends which do not correlate to c02 are routinely dismissed as either aerosols or heat going into the oceans, when it is very clear these are related to PDO cycles, which means climate sensitivity to c02 must be overstated. It is also clear that temperatures change more than expected due to the 11 year solar cycle, which means sensitivty to solar changes must be under-stated. These are empirical observations. It is also clear that c02 degasssing from oceans is not incorporated into the models from solar variations at all. I came to all these conclusions the same as yourself, but you have put them in graphical and mathematical form. Many of these are emprirical and quite strong, and the truth will out in the end.
I also add to your general theme the idea that time lag with respect to solar irradiance can be up to 40 years, which is evidenced in both solar proxies and also in daily and seasonal changes (eg warmth max 6 weeks after the summer solstice).
Good paper anyway, still got more reading to do on it.
Regards.
“Seeing as it’s logically impossible that the world warmed between 1997 and 2007, cooled between 1998 and 2008, and warmed again from 1999 to 2009 …”
My dear Mr. Black, given the way historical, measured temperatures are forced to dance up and down at the whim of whichever climate alarmist happens to be manipulating them today, the only logical impossibility around here is that any scientific knowledge might ever be gleaned from the resulting “evidence”.
Whilst I have severe reservations regarding the accuracy of the temperature record (given siting issues, coverage, stations drop outs, UHI, man made manipulation & continued revisions, etc), what would appear to be the case is that there is little temperature difference between the decade of the 1990s and that of the 2000s.
On that basis since there has been little change during the past 12 to 15 years, IF extreme weather events are due to warming, would one not have expected to see just as many and similar extreme events in the period from the mid 1980s through to say the late 1990s as one sees today?
The fact that there has on any basis been little further warming over the course of the last 10 to 15 years over and above that which had already occured by the mid/late 19902 suggests that recent extreme weather events are not the consequence of additional warming (there having been all but none these past 15 years) and therefore must be due to natural variability of weather events in an ever changing and chaotic world in which we live.
Bart, thanks very much for this comment and the links.
Bart,
Your comment “rang a bell” in my head. There’s a 2001 paper by Davis & Bohling in which they demonstrated both the ~1,000-yr and ~60-yr cycles in the GISP2 ice core…
Davis & Bohling, Fig. 6
Davis & Bohling, Fig. 7
They also identified possible harmonics at ~160-yr and ~320-yr; but these were relatively weak.
M.A.Vukcevic says:
“Thank you for your note. I am fairly familiar with harmonic and quasi-harmonic oscillations and the cross-modulation products.”
Vukcevic, I hope that you do not think that you are the only person on the Earth who is familiar with harmonic and quasi-harmonic oscillations and the cross-modulation products.
As I said above there are a lot of people that found a quasi 60-year cycle in several records.
Another record has been referenced by Middleton above.
Please give a look at
Davis & Bohling, Fig. 7
As also ferd berple says:
Jupiter and Saturn have a 60 year orbital harmonic (12 and 30 years). Over time, even a very small cyclical forcing will have a large effect if any of the systems on earth resonant at the same frequency.
So, there is a natural 60-year cycle and has an astronomical meaning. Actually this was the topic of my paper
N. Scafetta, “Empirical evidence for a celestial origin of the climate oscillations and its implications”. Journal of Atmospheric and Solar-Terrestrial Physics 72, 951–970 (2010), doi:10.1016/j.jastp.2010.04.015
Dr. Scafetta thank you for the further elaboration. Regarding the comment
http://wattsupwiththat.com/2011/07/11/the-bbcs-richard-black-engages-in-goldilocks-picking/#comment-698615
I would like to point that the reliability of the Greenland ice core data is coming under strong scrutiny. My observations are here: http://www.vukcevic.talktalk.net/CET&10Be.htm
The rest of your comments are appreciated, but would not whish to waste either your or my time in qualifying merits of the evidence.
thingadonta says:
July 12, 2011 at 12:21 am
“Variations in 20th century trends which do not correlate to c02 are routinely dismissed as either aerosols or heat going into the oceans, when it is very clear these are related to PDO cycles, which means climate sensitivity to c02 must be overstated.”
Yep, right on the money. But Gaia Modelers don’t do natural processes aside from heat transfers caused by radiation from the sun. As they admit (when not thinking about its implications), ENSO is an “emergent property” in the Gaia Models. They remain scientists, so-called, who have created no physical hypotheses that go beyond the 19th century work of Arrhenius.
ferd berple says:
July 11, 2011 at 10:41 pm
“Given the age of the earth and solar system, nature has had a very long time to shape the earth and oceans to match the cyclical forcings of the heavens.”
It does not need to. All you need is a lightly damped natural frequency mode and random noise which has energy in the appropriate band forcing it.
“The notion that something doesn’t exist because we haven’t found it only makes sense in the case of objects that are unlikely. There is nothing unlikely about cyclical natural behavior, including climate cycles. What is unlikely is non cyclical behavior. What should be assumed is that no event in nature is non cyclical until proven otherwise.”
Well stated. Natural frequencies of physical systems are… Natural. Ubiquitous. Universal. And, when you have fully two cycles of a 60 year oscillation evident within the higher accuracy, directly measured data spanning the previous century, and it appears all over the place in proxy reconstructions over thousands of years as well… Then, by gum, there’s a 60 year quasi-cyclic phenomenon influencing global temperatures.
nicola scafetta says:
July 12, 2011 at 8:33 am
“So, there is a natural 60-year cycle and has an astronomical meaning.”
I want to emphasize what I said above once again:
No additional outside source is needed.
I want to bring up the example of the Tacoma Narrows Bridge again. If you time it, you can see that the torsional mode of the bridge has a period of about 4 seconds.
There is no 0.25 Hz excitation – there is only the broadband excitation of the wind. The bandwidth of that wind input increased on that blustery day such that it started feeding energy into the mode. The bridge collapsed because the input energy could not be dissipated faster than the input energy before fatigue set in and the materials lost their integrity.
In the general case, if the system does not fatigue and fail, a steady state is reached whereby the oscillations are large enough that output energy balances input energy. Then, you get quasi-periodic, steady state oscillations which are effectively amplitude and frequency modulated within some range of the equilibrium.
This is not some revolutionary new theory. I’m just applying principles which have been known for at least 80 years.
The bridge collapsed because the input energy could not be dissipated faster than the output energy…