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
Bill Illis says: April 4, 2013 at 7:44 am
Here is 20 year spline smooth on Marcott’s published data.
Nice work, thanks for doing that.
Thank you Nancy for a clear analogy for us lay-people.
Steven Mosher says: April 4, 2013 at 7:41 am
paleo arguments about unprecedented are stupid on both sides.
throw all the paleo data in the trash bin and you still know from physics that C02 will warm the planet.
Fair enough.
But is not the big question “How much?”
Or do you already have all those feedbacks sorted and know the answer?
“Though scientists have known for many years, based on Antarctic ice cores, that temperature and CO2 were linked over the Ice Ages, establishing a clear cause-and-effect relationship has remained difficult. In fact, when studied closely, the ice-core data indicate that CO2 levels rose after temperatures were already on the increase, a finding that has often been used by global warming skeptics to bolster claims that greenhouse gases do not contribute to climate change.
Many climate scientists have addressed the criticism and shown that the lag between temperature and CO2 increases means that greenhouse gases were an amplifier, rather than trigger, of past climate change, but Shakun and his colleagues saw a larger problem” …. and here’s the UCAR contribution to the press campaign elevating Shakun and mis-representing the views held by many of you.
did I mention Siegenthaler’s leadership position with the Nieman Fellowship at Harvard or would that be gilding the lilly
Big volcanic eruptions are known to science to produce global cooling. Huge volcanic eruptions are known from sediment, to have occurred in the past. (One commenter upthread mentioned one in alaska that occurred around 1600 BC.) But they don’t show up in Marcott. It’s reasonable to assume that they should.
The rapid warming in the Younger Dryas is known to have occurred, despite “A mechanism to produce such a spike is not known to science.” So what? Science knows very little about the climate system and what makes it change.
All else being equal.
Except unequal else’s.
Richard, you are right that empiricism trumps all assumptions. Can you please point out the empiricism in this post? What did Anthony test and what methods did he use? Oh, right. None.
As far as trying to pull a null out of thin air and demanding that authors either disproved it or must accept it…that is nonsense. I can’t take a study about pollen charge and use it to demand that my null about alligator gestation must be accepted.
This is the Vostok graph I used to overlay on Marcott. It seems to show much more variation than the Vostok record record overlaid in red accompanying this article and Mike McMillan says:April 4, 2013 at 10:11 am
http://i49.tinypic.com/2s7cspl.jpg
justasking says: April 4, 2013 at 5:41 am
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 urbanization and industrialization?
Aaah. Good question, justasking.
I think we can safely come to the conclusion that UHI was not significant earlier in the Holocene. (evidence … complete absence of any evidence of “urban” anything, or any sign of massive global urbanization and industrialization ).
Therefore any earlier temperature spikes would have great significance, as we can perhaps fairly confidently assume that any such earlier temperature spikes, if they existed, very likely had other causes. Which would call into question somewhat the degree to which atmospheric CO2 may have contributed to 20th century warming.
Thomas says:
April 4, 2013 at 9:57 am
“Nancy, the number of proxies in Marcott’s study drops of sharply towards the end so the last spike is rather uncertain, except we happen to know from the instrumental record that there is a temperature increase there.”
The point is that the proxy data is of such low resolution that it could not show any spikes even if they occurred. Go back to the top and look at Charles the moderators plot. See all those spikes? These could well have occurred, but Marcotts data would never show it.
Look at the plot again. The current “instrument” spike doesn’t look unusual by comparison does it?
Regarding the graphs and discussion of Vostok, should we keep in mind that these are local temperatures but not global? After all, local temperatures can change rapidly, like yesterday to today at my house. Because warm air or water move around. I don’t see how global temperatures can do something similar.
Steven Mosher says:
“paleo arguments about unprecedented are stupid on both sides.”
The intention of these arguments is to convince; they prove nothing.
“throw all the paleo data in the trash bin and you still know from physics that C02 will warm the planet. Nothing can change that. Not paleo records, not modern records.”
Yes, but… This is the same thought that gets all the CAGW true believers in trouble. You, as a lukewarmer, only say ‘warm’, which is good since what we know from physics only supports limited warming. As opposed to what others claim to ‘know’. Not to mention that other physics processes may limit this warming even further.
@Steven Mosher says: April 4, 2013 at 7:41 am “paleo arguments about unprecedented are stupid on both sides. throw all the paleo data in the trash bin and you still know from physics that C02 will warm the planet.”
Steven, you obfuscate as usual (I will add to markx).
The contentious issue is anthropogenic CO2. Show us the proof for anthropogenic CO2 warming and what percentage of warming that may be attributed to ???
Thomas says:
April 4, 2013 at 9:57 am
“Richard, we have plenty of evidence that CO2 is a significant greenhouse gas that changes the temperature, even if people on this blog do their best to deny that fact.”
I can grant you that increases in manmade CO2 concentrations cause increases in temperature. But then the question is whether those changes are trivial. What is the magnitude of temperature change caused by manmade CO2 alone? How does it compare to the magnitude of the temperature change caused by an increase in water vapor alone? You don’t know, do you?
“Your null hypothesis regarding CO2 is not viable. You are just using it as a way of shifting all burden of evidence away from what you believe.”
What is his null hypothesis? Can you state it?
As I understand the Null Hypothesis, it is that temperature fluctuations are natural and that the magnitude of such fluctuations can explain just about all of the warming in the last 100 years. To falsify the Null Hypothesis, which is what you want to do, you must show that the warming in the last 100 years cannot be explained by natural fluctuations. That is going to be difficult because the decade of the Thirties was just as warm as the last decade. That conclusion about the Thirties will become universally accepted now that Hansen is no longer the manager of the temperature data.
You have bet on the claim that only increases in manmade CO2 can explain the non-trivial increases in temperature during the last 100 years. A moment’s reflection will reveal that your bet is a loser.
moshe, if the house burns down regularly(alternating climate optima and minima) how do you know it was an arsonist this time. Better, maybe your nasty arsonist just happened to be in proximity, but hadn’t lit a match. Correlation does not prove causation, and your faith in proof may be hanging an innocent man. There are plenty suffering today through this miscarriage of justice and science. Time for the appeal.
Others have pointed out the problem of your absolute expansion of lab results to the real world.
You’ve dodged around Muller’s attribution. In your heart, do you believe it?
Now, about Urban Heat Islands.
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Thomas:
I am answering your comments addressed to me in your post at April 4, 2013 at 9:57 am.
In my post at April 4, 2013 at 9:15 am I tried to explain a basic scientific principle in sufficiently clear language for you to understand it.
There is no possibility of explaining anything to somebody who chooses not to understand. And your reply to me says you prefer superstition to science. Therefore, I would have ignored your reply were it not for you asking me some specific questions.
I am bothering to answer your reply because – although I recognise you choose not to learn from reason – I would not want you to convince yourself that I am stumped by your questions.
You say to me
There is absolute and certain evidence that CO2 is a greenhouse gas, but there is no evidence – none, zilch, nada – that an increase to atmospheric CO2 from present levels will have any discernible effect on global temperature. And there is evidence that it cannot have a discernible effect. I explained one of the reasons for this to you in my post (I,e. negative feedbacks), but you say you prefer your superstitious belief to scientific evidence.
I accept scientific evidence whether I like what it indicates or not.
You really, really do insist on misunderstanding when you talk about [my] Null Hypothesis. The scientific method decrees the Null Hypothesis; not me, not you, and not anybody else. Were you not blinded by your superstition then you would have read that I wrote
There is nothing “ironic” in my telling you about this because – contrary to the delusion created by your superstition – Nancy’s analogy EXPLAINS an implication of the Null Hypothesis.
And her analogy does not say anything “ought” to be: it points out that something probably – but not certainly – IS.
And words fail me in expressing my astonishment that anybody would write as you do
That is three logical fallacies in two sentences.
1.
Correlation is not causation.
“We have observed both the milk turning sour and an increase in witches in the last century”.
2.
‘Argument from ignorance’ is a classical logical fallacy.
It is superstitious nonsense to ascribe whatever cause you want (be it CO2 or witches) merely because you don’t know the true cause of an observed effect.
3.
And the Null Hypothesis would have been refuted if a clearly observed effect were that
CO2 rise causes global temperature rise.
But that is NOT a clearly observed effect: CO2 has continued to rise while global temperature has NOT risen for at least the last 16 years.
Also, atmospheric CO2 concentration change follows temperature change at all time scales: a cause cannot follow its effect (without use of a time machine).
There is no “bias” in my “selection of papers”.
Those are the papers which – as I said – provide empirical derivations of climate sensitivity. They use very different methods, each analyses a different data set, and they each deduce climate sensitivity is ~0.4 deg.C for a doubling of atmospheric CO2.
And I don’t have a clue what you mean when you write
“Could you also explain what the difference is between “climate sensitivity” that you claim, based on a very biased selection of papers, is low and “natural climate sensitivity” that you claim is much higher?”
What ““natural climate sensitivity” that [I] claim is much higher”?
I mentioned no such thing!
You say Spencer has some dispute with one of the papers I cited. Good, that is how science is done. Evidence is challenged.
And you are further deluded when you claim I have “chutzpah” by citing scientific papers in refutation of your superstition. You are entitled to your superstition, but your superstition does NOT give you the right to deride my respect for science, the scientific method, and the findings of science.
Richard
Thomas says:
April 4, 2013 at 9:57 am
. . . .
“I think this will be enough from me for now. As wte9 put it the idea here is to “wallop” any dissenters anyway, proving you are right not by strength of your arguments but by numbers. A local consensus.”
Dear Lord, Thomas. The “wallop” I mentioned clearly referred to those commenters who had previously refuted your *premise,* which is demonstrably incorrect. No one here advanced any argument by consensus. Our argument isn’t made any stronger or weaker because more than one individual told you you were wrong. If you have a problem with people taking your flawed reasoning to task, then don’t comment here. You are quite thin-skinned.
It’s really remarkable how you try to twist the scientific method and logic on its head to support your case. You incredibly wrote: “Your statement ‘There is only one Null Hypothesis: i.e. it has to be assumed a system has not changed unless it is observed that the system has changed.’ is rather ironic given Nancy’s belief that there ought to have been earlier spikes in temperature even if we can’t observe them. On the other hand, we have observed both an sharp increase in CO2 and in temperature the last century. That’s why your null hypothesis fails.”
First, Nancy doesn’t have a belief as to earlier spikes as you assert, she has a testable hypothesis. Conflating the two is inexcusable. Second, you run afoul of post hoc ergo propter hoc. The null hypothesis doesn’t change because there is a correlation between temperature and C02 during part of the 20th Century. That the two have, at times, risen simultaneously proves nothing. We’re saying you haven’t proven your case about a causal relationship between C02 and temperature and that to robustly do so you need to show that similar spikes haven’t happened at other points in the Earth’s history independent of C02 and/or man’s influence. Surely you acknowledge that the C02 hypothesis would at least be open to criticism if that had, in fact, happened?
Bottom line: There is no burden shifting, you still have to prove your assertion with data.
Ryan Gainey:
re your post addressed to me at April 4, 2013 at 10:53 am.
Please read my post you claim to be replying. It answers all your points and questions.
Richard
@Vince Causey 11:13amThe point is that the proxy data is of such low resolution that it could not show any spikes even if they occurred
Perhaps all we see are the spikes. The proxies show the envelope of maximum temperatures.
Life is a very non-linear process. Why should we believe that whatever the proxy is measuring is the average temperature or even can be correlated to average temp. From a biological process point of view, we might be better corrolated to the maximum weekly temperature of the year.
IF the proxies measure temperature to any significant correlation, what calibration do we have that they are closer to average than max?
rogerknight, You are correct that volcanoes produce cooling, but only for a few years, much shorter than what we are talking about here, and there is as far as I know no mechanism to get similar warming spikes.
markx “Are stating here that you consider the 20th century temperature spike is ‘proven’ because you know CO2 levels have risen? ”
No, I consider it proven because we have observed it.
Theo ” That is going to be difficult because the decade of the Thirties was just as warm as the last decade.” No temperature reconstructions shows anything even close to that.
“To falsify the Null Hypothesis, which is what you want to do, you must show that the warming in the last 100 years cannot be explained by natural fluctuations.”
Now, this is a fundamental misunderstanding of how science works. You can *never* prove that something can’t be caused by some unknown process. Maybe gravity doesn’t exist and it’s just angels pushing the planets around. How do you disprove that? In science you create different hypothesis how something works, calculate what predictions they make, and make measurements to see which hypothesis works best. It may not be perfect, but until you find something better you work with the theory you have, trying to find the boundaries for where it is useful.
Richard, repeating a statement like ” but there is no evidence – none, zilch, nada – that an increase to atmospheric CO2 from present levels will have any discernible effect on global temperature.” doesn’t make it true. Repeating claims about negative feedbacks don’t make them true. You didn’t “explain” about negative feedbacks, you asserted them, contrary to mainstream science.
” Nancy’s analogy EXPLAINS an implication of the Null Hypothesis.” No, Nancy claims that you should expect warming spikes in the absence of either measurements or theoretical reason to see them, the absolute opposite of the null hypothesis as you define it.
“Correlation is not causation” Yes, I know that. I considered pointing it out but considered that no one would be stupid enough to misunderstand me. I apologize for my mistake. Go back to your post from 9:05 where you tried to trivialize the observed warming in order to get your null hypothesis to fit. It doesn’t: we have observed warming. That was my entire point. You can’t use the null hypothesis to “disprove” AGW the way you tried to do.
“It is superstitious nonsense to ascribe whatever cause you want (be it CO2 or witches) merely because you don’t know the true cause of an observed effect.”
Now you are being silly. Surely you are aware that we have had good scientific reasons to believe CO2 causes warming for well over a century. It’s not a matter of what I want but of what existing science tells us.
” CO2 has continued to rise while global temperature has NOT risen for at least the last 16 years.”
Actually we do have a positive trend over 16 years, and climate models show that you expect periods with more and less warming even if you in the longer term has a steady trend. There is internal variation in the climate system.
“Also, atmospheric CO2 concentration change follows temperature change at all time scales: a cause cannot follow its effect ”
Historically CO2 has acted as a positive feedback, amplifying e.g. the ice age cycles. There is unfortunately no good historical analogy to our current large scale burning of fossil fuels. It’s terra incognito, an interesting scientific experiment although somewhat risky to experiment on the planet we live on.
“There is no “bias” in my “selection of papers”.” Of course there is. I have no idea how many papers there are trying to estimate climate sensitivity, but they must be in the hundreds, and you pick three of the ones with the lowest sensitivity. Check the references in the IPCC report for other papers.
“What ““natural climate sensitivity” that [I] claim is much higher? I mentioned no such thing! ”
You could have gone back and read what you wrote: “The feedbacks in the climate system are negative and, therefore, any effect of increased CO2 will be probably too small to discern because natural climate sensitivity is much, much larger. “
I’m very surprised an astronomer hasn’t chipped in here to show that the analogy is a bad one. The resolution of telescopes still isn’t good enough to view extrasolar planets directly. What we have is indirect evidence such as the transit of a planet making a momentary dip in the light being received from that star.
There’s a well known abrupt cooling event followed by a fast warming period that is not easily visible in the Marcott charts: The 8.2ka event.
Ryan says:
April 4, 2013 at 8:03 am
argumentum ad ignorantiam
Thomas says:
April 4, 2013 at 12:37 pm
…
——–
There’s so much wrong in what you said that I’m having a hard time deciding what to run with. Maybe a reset is in order, since I count 10 separate points in your last post. Of all the rubbish you’ve been arguing, what do you consider the most important point, or maybe the most important two or three?
Thomas says:
April 4, 2013 at 12:37 pm
Well, he says a lot but I think it can be summarised as:
1 We know that CO2 causes warming
2 We know that CO2 was released by industrialisation in the twentieth century
3 We know that the world warmed in the 20th century
Therefore,
4 Industrialisation caused the warming
He also implies that that is bad.
However, the challenges remain:
Point 1: How much warming for CO2? Is it a constant amount? If it can pause for a generation is it significant? How do you measure it?
Point 2: How much of the CO2 rise is from industrialisation? How much is due to changes in the natural balance? Why do ice cores show CO2 levels following global temperature by a few centuries but the effect of the medieval warm period is not counted by any model? And what would that effect be?
Point 3: No-one disputes the world warmed but not in anyway that can be related to CO2 rises alone. Something else must be significant, but what (the weather?) As we all agree that the effects of CO2 can be overwhelmed in the twenty-first century (for the moment at least) why would that not continue?
Point 4 can only be answered with, “So what?” If it’s worth answering at all.
However, Thomas makes it clear that he starts from the premise that AGW is proven and any contrary evidence should be discounted. It is no surprise that he has trouble following the scientific method. Empirical evidence will be contaminated by a biased selection and theoretical speculation (models) if you already know the truth.
That may be why he cannot doubt the models regardless of what actually happens.