Story submitted by WUWT reader Nancy Green
There is a message in Marcott that I think many have missed. Marcott tells us almost nothing about how the past compares with today, because of the resolution problem. Marcott recognizes this in their FAQ. The probability function is specific to the resolution. Thus, you cannot infer the probability function for a high resolution series from a low resolution series, because you cannot infer a high resolution signal from a low resolution signal. The result is nonsense.
However, what Marcott does tell us is still very important and I hope the authors of Marcott et al will take the time to consider. The easiest way to explain is by analogy:
50 years ago astronomers searched extensively for planets around stars using lower resolution equipment. They found none and concluded that they were unlikely to find any at the existing resolution. However, some scientists and the press generalized this further to say there were unlikely to be planets around stars, because none had been found.
This is the argument that since we haven’t found 20th century equivalent spikes in low resolution paleo proxies, they are unlike to exist. However, this is a circular argument and it is why Marcott et al has gotten into trouble. It didn’t hold for planets and now we have evidence that it doesn’t hold for climate.
What astronomy found instead was that as we increased the resolution we found planets. Not just a few, but almost everywhere we looked. This is completely contrary to what the low resolution data told us and this example shows the problems with today’s thinking. You cannot use a low resolution series to infer anything reliable about a high resolution series.
However, the reverse is not true. What Marcott is showing is that in the high resolution proxies there is a temperature spike. This is equivalent to looking at the first star with high resolution equipment and finding planets. To find a planet on the first star tells us you are likely to find planets around many stars.
Thus, what Marcott is telling us is that we should expect to find a 20th century type spike in many high resolution paleo series. Rather than being an anomaly, the 20th century spike should appear in many places as we improve the resolution of the paleo temperature series. This is the message of Marcott and it is an important message that the researchers need to consider.
Marcott et al: You have just looked at your first star with high resolution equipment and found a planet. Are you then to conclude that since none of the other stars show planets at low resolution, that there are no planets around them? That is nonsense. The only conclusion you can reasonably make is that as you increase the resolution of other paleo proxies, you are more likely to find spikes in them as well.
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As a primer for this, our own “Charles the Moderator” submitted this low resolution Marcott proxy plot with the Jo Nova’s plot of the Vostok ice core proxy overlaid to match the time scale. Yes the vertical scales don’t match (numerically on the scales due to the ticks being different and the offset difference), but this image is solely for entertainment purposes in the context of this article, and does make the point visually.
Spikes anyone? – Anthony
![marcottvostok2[1]](http://wattsupwiththat.files.wordpress.com/2013/04/marcottvostok21.jpg?quality=83)
(Added) Study: Recent heat spike unlike anything in 11,000 years “Rapid” head spike unlike anything in 11,000 years. Research released Thursday in the journal Science uses fossils of tiny marine organisms to reconstruct global temperatures …. It shows how the globe for several thousands of years was cooling until an unprecedented reversal in the 20th century. — Seth Borenstein, The Associated Press, March 7th
Note: If somebody can point me to a comma delimited file of both the Marcott and Vostok datasets, I’d be happy to add a plot on a unified axis, or if you want to do one, leave a link to the finished image in comments using a service like Tinypic, Imageshack or Flickr. – Anthony
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Apr 3, 2013 at 6:19 PM | Unregistered CommenterDocMartyn on Bishop Hill summed it all up rather effectively in my opinion:
Average out the contents of your current account ever since you started work and then add on to the end of the series the contents on the day of your last paycheck. (paraphrased)
Sums up the Uptick for me!
Ivor Ward
Just exactly what constitutes a ‘spike’?
izen:
Your post at April 4, 2013 at 2:13 am says in total
So what?
Comparing low temporal resolution data to high temporal resolution data is apples-/-oranges and meaningless.
And that is what this thread is about because that is what Marcott et al. did.
There are finer resolution global temperature data which DO show past spikes comparable to the last century warming.
For example, the above graph which overlays Vostock data shows several such spikes.
Funny how warmunists claim the Vostock data provides global information when it suits their purposes but claim that same data is “meaningless” when it doesn’t fit their purposes.
And if all finer resolution global temperature data did not show past spikes comparable to the last century warming (n.b. some do) then that would be meaningless because
absence of evidence is NOT evidence of absence.
And that is also what this thread is about.
Richard
You assume CO2 caused warming.
You assume this warming will remain for centuries
You assume Marcott’s proxies and methods would have picked up this warming.
You assume the current assumed CO2 induced warming is unprecedented.
You assume too much.
I presume you don’t understand how the scientific method works.
Excellent article, Nancy Green. The great truths are often very simple.
In answer to Leif Svalgaard whom I respect greatly but who I think on this occasion has fallen into the trap of making a word-based argument:
Yet another analogy, from the world of accounting this time. (That’s where I’ve spent much of my working life.) Say that I have the total salary remuneration paid by a company for the last 20 years. For affirmative action reporting purposes I am now required to break this down, trend it and chart it, categorized by race, gender, age, disabilities, etc.
If all I have is the statistical snapshot for the latest financial period, and no breakdown for the previous 19 periods, the data resolution is too coarse. It is impossible to infer anything reliable about the previous financial periods. No contortion of language can upset that conclusion.
trafamadore says:
April 3, 2013 at 8:26 pm
If I may paraphrase to help us (as you implied) simple minded WUWT readers – “Yeah, well, despite the outlandish takeaway headlines we were aiming for, we really did too have our fingers crossed!”
@Thomas:
“This analogy only works if you start by assuming that there is nothing special about the 20th century, i.e. that there can be no antropogenic warming, and since Watts is using it to claim there is nothing special about the 20th century it becomes a circular argument.”
Can you explain, without invoking an argument from authority, the precautionary principle or faith, how you haven’t turned logic on its head here? I suspect that once you look behind the press releases to uncover the real lack of empirical proof for anthropogenic warming on the scale alarmists would have us believe, you will find that your assertions are the ones that rest, squarely, on circular argument.
Or are you just another hit and run commenter unwilling to justify your boilerplate argument?
Mod: wanted to comment on the Hansen supporting nuclear power article. However the log in is being weird. Could you check it?
[nothing wrong here that I can see . . mod]
@Itzen:
“Comparing local temperature spikes to a global reconstruction is apples-/-oranges and meaningless.”
Indeed. Seems to be what people here have been saying for a long time.
“There are finer resolution global temperature data which also show no past spikes comparable to the last century warming.”
Where? If you could find me a proxy that has been accurately calibrated to the ENTIRE unadjusted modern temperature record (one like HadCRUt as opposed to GISS that smears wildly variable arctic temperatures over thousands of miles and gradually reduces all sampling from a mixture of urban and rural to exlusively airports over the late 20th century), agrees with it without any truncation of data, can be demonstrated through comparison to the instrumental record to have a resolution of less than 30 years, does not have to go through statistical manipulation akin to using a photoshop skew / rotate (or invert) tool on a graph to show correlation with the instrumental record, is demonstrably not subject to bias from external factors, like grazing sheep or CO2 levels (without these biases being arbitrarily ‘corrected’ for, correlates convincingly across its entire record with a large number of proxies in other locations of the same nature, can, through the application of rigid tests (not ones made up to suit the occasion), be shown to be impervious to contamination from the act of extraction, then I will believe you. Otherwise, what you say just looks like hand waving to me.
For a short spike in the graph to occur in the past comparable to today’s rise, it would have to show up on the same sample in most of the 70 some proxies.And then the spike would be the average of all the proxies and may would have the amplitude comparable to today. What is the likelihood that they have all the centuries lined up exactly. And have you seen the spaghetti graph of all the proxies together on one chart. There is no way a 1 century spike of half degree would ever survive that mess.
@Go Home
I think that even if the resolution had been high enough to detect any such spike it appears to my layman’s mind that given the core top redating of most of the proxies to 1950 and given the fact that the very nature of sediment sampling can destroy or disturb up to the top two feet of the sample, making the actual start date anything up to and including 1000 years BP it not only seems unlikely that any such spike would survive their methods but I suggest it’s a physical impossibility.
It’s clear that the majority of their data has ended up in the wrong bins when sorted and none of them in alignment.
Go easy on me. I did say layman right?
Everyone who reads WUWT is not a statistitian. Nancy Green the analogizing machine. Thanks for a good laymans read.
Besides, everyone knows 37.987% of statistics could be maybe mistaken.
On sampling, I can sample a pure sine wave at fixed intervals which are multiples of its period. The result will be a set of constant equal values and no averaging of the samples will help.
The constant could be non-zero, whereas the true average value of a sine wave will converge to zero.
Aliasing is not just bad, it can be downright misleading.
MarkT is right. Leif’s comment does not hold and, ironically, over-states his case.
Excellent observation.
This helps explain the failure of the hockey sticks.
It is difficult to imagine that trained academics could simply as a group over look this.
But that raises the question of motive.
@ur momisugly toto
and how exactly do you know it is *durable*? give it another 200 years or so and I will be the first to agree.
Great post and excellent comment by Benfromo.
Must point my mates Muchrot Scheissen et al in the direction of this web site 🙂
“Yes you can. You can infer the long-term trend among other things. Don’t overstate your case.”
You can’t. If there is a longer term trend then you need to have longer term data. It says nothing about short term periods, this is what in the discussion.
Zoot,
From one layman to another, i whole heartedly agree. Re reading my post, i see my writing skills still lack robustness. Rewriting one line…
“And then the spike would be the average of all the proxies and would no way have the amplitude comparable to today.”
Please !!
Don’t cite any fairy tale, I mean, “news” story by Seth Borenstein
The takeaway is you can’t look at long period low-resolution temperture proxies and compare them with the short period modern high resolution instrument record and conclude that we are in a period of unprecedented warming OR that there were no such periods in the past.
Are the large temperature upticks caused by UHI in the last century matched by UHI increases earlier in the Holocene during similar periods of massive global urbanisation and industrialisation?
John Blake says:
April 3, 2013 at 11:33 pm
John, thank you very much for your comments. I am now going to start using a loose paraphrase of your statment:
“The science of Climatology has the same predictive capabilities as Botany.”
Dear Cousins
A rare an interesting event is occurring in Central London it’s snowing.
Take care
🙂
We are cooling, Leif, for thousands and thousands of years. For how much longer, even kim doesn’t know.
===================
benfrommo says:
April 4, 2013 at 12:23 am
Excellent post, Ben. You nailed everything. Your exposition of observer bias is clear and simple. Your diagnosis of the Alarmist malady, searching for any statistic that supports CAGW, explains the Alarmist obtuseness regarding scientific method.