Guest post by Steve Goddard
Archimedes had his eureka moment while sitting in the bathtub. Newton made a great discovery sitting under an apple tree. Szilárd discovered nuclear fission while sitting at a red light.
There was a time when observation was considered an important part of science. Climate science has gone the opposite direction, with key players rejecting observation when reality disagrees with computer models and statistics. Well known examples include making the MWP disappear, and claiming that temperatures continue to rise according to IPCC projections – in spite of all evidence to the contrary.
Here is a simple exercise to demonstrate how absurd this has become. Suppose you are in a geography class and are asked to measure the height of one of the hills in the Appalachian Plateau Cross Section below.
Image from Dr. Robert Whisonant, Department of Geology, Radford University
How would you go about doing it? You would visually identify the lowest point in the adjacent valley, the highest point on the hill, and subtract the difference. Dividing that by the horizontal distance between those two points would give you the average slope. However, some in the climate science community would argue that is “cherry picking” the data.
They might argue that the average slope across the plateau is zero, therefore there are no hills.
Or they might argue that the average slope across the entire graph is negative, so the cross section represents only a downwards slope. Both interpretations are ridiculous. One could just as easily say that there are no mountains on earth, because the average slope of the earth’s surface is flat.
Now lets apply the same logic to the graph of Northern Hemisphere snow cover.
It is abundantly clear that there are “peaks” on the left and right side of the graph, and that there is a “valley” in the middle. It is abundantly clear that there is a “hill” from 1989-2010. Can we infer that snow cover will continue to increase? Of course not. But it is ridiculous to claim that snow extent has not risen since 1989, based on the logic that the linear trend from 1967-2010 is neutral. It is an abuse of statistics, defies the scientific method, and is a perversion of what science is supposed to be.
Tamino objects to the graph below because it has “less than 90% confidence” using his self-concocted “cherry picking” analysis.
So what is wrong with his analysis? Firstly, 85% would be a pretty good number for betting. A good gambler would bet on 55%. Secondly, the confidence number is used for predicting future trends. There is 100% confidence that the trend from 1989-2010 is upwards. He is simply attempting to obfuscate the obvious fact that the climate models were wrong.
Science is for everyone, not just the elite who collect government grant money. I’m tired of my children’s science education being controlled by people with a political agenda.
Steve Goddard (15:11:50) :
You can’t strip away oceans and vegetation from CO2 analysis, because they are responsible for the vast majority of CO2 emissions and absorption.
I thought the C)2 molecules were the culprits…
Not to mention that the ocean holds almost all of the latent heat in the climate system.
I thought all that came from the Sun. Now, I’ll grant that the Sun was dimmer back then, so the influence of CO2 must have been even more important. Perhaps the absence of plants helped warm the Earth…
Leif Svalgaard (13:17:56) :
vigilantfish (12:26:36) :
the idea of climate being defined by 30-year intervals
If you read carefully you’ll see that the 30-year mean should be updated every 10 years. So, every 10 years we can have a new climate ‘assessment’, if you like.
Leif:
Thanks for the information. I’ve learned stuff from you today. I have to say that I’ve enjoyed your contributions at WUWT.
Leif,
What is the point of the dry sarcasm? It isn’t particularly clever.
Show me a “statistically significant” correlation between CO2 and temperature during the Phanerozic.
Michael Hauber,
The height of a hill is a fairly simple concept which most people can understand. I continue to be surprised by those who can’t.
Steve Goddard (17:49:20) :
Show me a “statistically significant” correlation between CO2 and temperature during the Phanerozic.
Wouldn’t that be cherry picking too? Anyway:
As already discussed on this blog, there is a good correlation, e.g. http://droyer.web.wesleyan.edu/climate_sensitivity_PNAS_commentary.pdf
“it is clear that during the Cretaceous and Paleogene climate sensitivity commonly exceeded 3°C per CO2 doubling.”
Steve Goddard (17:49:20) :
What is the point of the dry sarcasm? It isn’t particularly clever.
I don’t do sarcasm, and especially not if not clever. I really mean that having a clean cut radiation-driven determination of the emission/absorption issue with complicating circumstances would teach us something. I even gave you an example of how such separation was used to unravel how geomagnetic activity depends on the solar wind: http://www.leif.org/research/suipr699.pdf
I have a feeling that you didn’t even look…
Now for the 8th time, how about overplotting the snow cover data on the model graph? That would at a glance show how the two compare.
issue withOUT complicating circumstances …
Leif,
Look closer at the graph. The relationship between CO2 and temperature in the Cretaceous was coincidental. It was totally different in the Tertiary.
http://i224.photobucket.com/albums/dd137/gorebot/Geological_Timescale_op_927x695.jpg
If people want to claim a dependent relationship between CO2 and temperature demonstrating the greenhouse effect, then they need to include all the relevant data.
“Show me a “statistically significant” correlation between CO2 and temperature during the Phanerozic.”
If you know (because I demonstrated it) that CO2 and temperature are tightly correlated over the past 800,000 years, why on earth would you want to make an issue of what the correlation was 500 million years ago, when accurate measurements are going to be much harder to come by? If the relationship has held for 800,000 years, why would you think it was any different in the distant past, or if for some strange reason it were, why would we care?
If there was a relationship between CO2 and temperature for 800,000 years, then whatever that tells us continues to apply today. Speaking of using your common sense.
Steve Goddard: http://i224.photobucket.com/albums/dd137/gorebot/Geological_Timescale_op_927×695.jpg
Why is it that Scotese assembles the worst graphs on T/CO2 record on the web, and yet his are the most cited?
The Cainozoic record is utterly wrong (where’s the PETM? The Oligocene Ice age? The Miocene Climatic Optimum?); the Jurassic was cool?; the Late Carboniferous/Early Permian Ice Age is shifted to the Mid-Carboniferous; the very brief end Ordovician Ice Age covers most of the period; and where’s the Snowball Earth in the Neoprterozoic? I won’t even start on the apparently random squiggle that represent CO2.
ginckgo (18:52:46) :
Why is it that Scotese assembles the worst graphs on T/CO2 record on the web
The question is why Steve cherry picked that worst graph? That doesn’t even prove his point.
Hey, Steve, read this:
http://motls.blogspot.com/2009/12/no-statistically-significant-warming.html
Now, reflect.
Ron Broberg,
People who are attempting to show a dependent relationship between CO2 and temperature have to demonstrate statistical significance in order to forecast future temperature trends.
I am not making any attempt to claim a causal relationship between the date and snow extent, and am not making any attempt to forecast future trends. I am just showing that snow extent has increased during the last 20 years.
Do you see the difference? There is absolutely no need for statistical analysis to prove that winter snow extent is greater now than it was 20 years ago. All it requires is a few measurements. It is remarkable how confused people seem to be about this.
Re: Robert (Feb 22 18:51),
If there was a relationship between CO2 and temperature for 800,000 years, then whatever that tells us continues to apply today. Speaking of using your common sense.
I agree. The ice core record http://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Vostok-ice-core-petit.png/400px-Vostok-ice-core-petit.png shows clear correlation.
It is of course important not to lose sight of the fact that correlation is not causation, and that the same record shows an 800 year lag at least of CO2 to temperature.
In fact, from elementary physics of solids liquids and gases one could hand wave that the concentration of any trace gas would be correlated with the temperature.
Why are we in this discussion on this board?
Robert,
The ice core records show CO2 in a narrow range between 200 and 300ppm, following ocean temperature changes, due to changes in CO2 solubility in seawater. They tell us little or nothing about climate sensitivity. What they show is that seawater outgasses CO2 at higher temperatures and absorbs it at lower temperatures.
The geologic record for the last 600 million years shows much larger swings in CO2 – up to 4,000ppm. Don’t you think they should provide much more useful information than ice cores in calculating sensitivity?
ginckgo, Leif,
Why don’t you two get together, find your favorite CO2/temperature graph, and calculate the climate sensitivity and statistical significance of the relationship between CO2 and temperature?
Again, quoting William Briggs :
http://wmbriggs.com/blog/?p=1958
Re: ginckgo (Feb 22 18:52),
Can you give a better link?
If the link you provided was supposed to be it, it does not work, it gives:
photobucket.com/findstuff/?httpstatus=404 (took the http off so it would not become a useless link)
Leif,
You didn’t read ginckgo’s comment very carefully before firing your volley. ginckgo said that Scotese’s graph was the “most cited.” Do you think that using the “most cited” graph is “cherry picking?”
Or more likely you just didn’t read very carefully.
Here is another widely used one which shows even less correlation.
http://ff.org/centers/csspp/library/co2weekly/2005-08-18/dioxide_files/image002.gif
A couple of things about the geological record of T and CO2:
GHGs have varying influence on temperature depending on other factors that can swamp their impact (eg changes in continental arrangements and ocean currents).
CO2 does not have to be the primary driver for every climate change in the past for it to fulfill that role today.
The CO2 values for the deep past are much more difficult to calculate than for the past few 100kyr, and yet they are happily taken to be accurate here (selective skepticism?).
The 800 year lag is also problematic, because I gather that the error margin on sample dates ranges from several 100 years to over 1000 years.
If CO2 is more effective a GHG at low concentrations (which appears to be correct), then the 1000+ppm of the past are not overly relevant today.
anna v (20:46:40) :
Re: Robert (Feb 22 18:51)
Ever considered the ~800 year lag could be related to the ~1600 year thermocline current turn-over time? Half of a cycle?
Re: Leif Svalgaard (Feb 22 09:32),
I am puzzled. You must be using this graph?
http://i224.photobucket.com/albums/dd137/gorebot/Geological_Timescale_op_927x695.jpg
If I were presenting it in a lecture, I would point out that there is a correlation 500 million years ago, where the fine structure is not measurable. In the last 500 years, where there is more detail ( if correct) correlations are moot. There are times that the CO2 is much in fore and the temperatures are constant, defeating the point that CO2 is a driver of temperature.
Why are we having this discussion? I insist one can fit 100 angels on the point of a pin.
Steve Goddard: People who are attempting to show a dependent relationship between CO2 and temperature have to demonstrate statistical significance in order to forecast future temperature trends.
Gibberish. Forecasts of future temperature trends are not made from ‘statistical significant current trends.’ Climate models run simulations based on a range of calculated and parametrized physical properties of the climate. Those forecasts do not depend on whether or not the last 15 years show a statistically significant trend.
I am not making any attempt to claim a causal relationship between the date and snow extent, and am not making any attempt to forecast future trends. I am just showing that snow extent has increased during the last 20 years.
And here I am just showing that global temperature anomalies have increased during the last 20 years.
You cannot draw a ‘trend’ in a time series and then claim that you are not drawing a relationship between the date and the snow extant. [b]The linear trend is a mathematical expression of the relationship between the data and the snow extant.[/b] Read that again. You are doing one thing (literally drawing a relationship between time and snow extant) and then denying that you are doing it. Is it just confusion? I hope so.
Do you see the difference? There is absolutely no need for statistical analysis to prove that winter snow extent is greater now than it was 20 years ago.
Here is your problem, Steve, if you are actually confused and not just being defensive.
It is a physical fact that NH snow extant in Jan 2010 was greater than in Jan 1989.
It is also a physical fact that global temp anomaly was greater in Jan 2010 than in Jan 1989.
It is also a fact that a fitted linear trend is positive for both data sets.
It is also a fact that a fitted linear trend is a mathematical expression between the date and the variable being charted.
Your reply that statistically significance should be applied to temperature anomaly trends and not to snow trends because statistical significance is required to ‘prove’ CO2 warming is nonsense. Statistical significance (or lack thereof) is a property of time series, a way of separating real trends from noisy data. You have identified a statistically insignificant trend (that straight line you keep drawing) in a noisy data set and, when that fact is pointed out to you, you have resorted to defenses that are silly.
Admit the mistake (I’m a newbie at stats, I make lots of them) and move on.
Re: wayne (Feb 22 22:04),
Ever considered the ~800 year lag could be related to the ~1600 year thermocline current turn-over time? Half of a cycle?
Who knows? For sure the turn over from the lower ocean waters to the surface is important but one would need data on the current at those times to have a quantitative estimate.
From page 28 of Richard Rhodes’ The Making of the Atomic Bomb:
Leo Szilard discovered the concept of a nuclear chain reaction, not fission itself. He later went on to take out a British patent for the nuclear chain reaction. This patent was later transferred, in secret, to the British government when the military applications seemed imminent. The War Office turned down the patent offer noting “there appears to be no reason to keep the specification secret so far as the War Department is concerned.” Later the Admiralty accepted the patent.
I strongly recommend the above book for anyone’s library. It is a wonderful journey through history and science.