Where would we be without science? Today, we live longer than ever before according to the Royal Geographical Society, thanks to pharmaceutical, medical, and health science. Vaccines saves many lives. Physics and electronics have given us satellites, telecommunications, and the Internet. You would not read this blog without them. Chemistry and biology have provided use with all sorts of products, food, and enabled the agricultural (“green”) revolution enhancing our crop yields. The science of evolution and natural selection explains the character of ecosystems, and modern meteorology saves lives and help us safeguard our properties.
So what is science? It’s more than just a body of knowledge. It’s a mindset and strategy to build an understanding of our world. This understanding is extremely valuable for our society, especially when it comes to establishing where we stand and what the likely outcomes will be from perceived future actions.
The scientific method is perfect for resolving uncertainties such as controversial claims about facts. It builds on the principles of transparency, testing, and independent replication. Every scientifically trained scholar should get similar results when the analysis is repeated for a finding that is universally true.
Scientific testing and replicating scientific facts are usually based on data analysis and require an understanding of statistical reasoning and what the data really represent. The data analysis is often the point where differences arise. Climate science is no different to other science, and I have myself contributed to the process of checking the findings in a number of controversial papers (Benestad et al., 2016).
There is always a story behind each conclusion that goes back to its roots. The difference between science on the one hand, and dogma and propaganda on the other, is that the latter is not traceable. In other words, you should be more confident about scientific results and sceptical when it comes to intransparent or undocumented claims.
The scientific community has a well-established system for taking care of scientific findings, mainly through publication of papers in the scientific literature. A scientific paper should provide sufficient information for others to replicate the work done and reproduce results. Scientific results are also presented and discussed at conferences, such as the present American Geophysical Union (AGU) fall meeting. The science presented in conferences, however, is not readily broadcasted to the wider society, partly because of difficult language and partly because of limited media presence.
I strongly believe we need a public voice of scientists and historians (see Defending Climate Science), but there is a concern for the future of Earth and space science. It is not just a potential problem for the science community. This is also a genuine worry that affects the wider society and its right to scientific facts and objective information. It is also an issue when it comes to education.
Science benefits everyone and is part of the fabric of our civilisation. It is therefore unwise to dismiss or twist for short-term benefits. The concept “science denial” has been discussed in the magazine called Physics World (September 2016), Nature, blogs, videos, as well as books, just to mention some examples. One of my favoutites is nevertheless the book with the title ‘Agnotology: the Making and Unmaking of Ignorance‘ by Proctor and Schiebinger
History of science can explain how absurd the notion is regarding global warming being a hoax from China. We only need to search for scientific publications from the past, as I did when I wrote a review about the greenhouse effect, based on a paper from 1931 by the American physicist Edward Olson Hulburt (Benestad, 2016)). There is an excellent historical account of modern climate science American Institute of Physics written by Spencer Weart.
It is also a disservice to our society to close down faculties, such as earth observations and climate science. We need both observations and updated analysis more than ever in the times of unprecedented global warming. They are essential inputs to fact-based decision-making concerning our global environment on which we all depend. Our society has progressed and become great much thanks to science, and it would be a sad story for everyone if we were to undo that.
References
- R.E. Benestad, D. Nuccitelli, S. Lewandowsky, K. Hayhoe, H.O. Hygen, R. van Dorland, and J. Cook, "Learning from mistakes in climate research", Theoretical and Applied Climatology, vol. 126, pp. 699-703, 2015. http://dx.doi.org/10.1007/s00704-015-1597-5
- R.E. Benestad, "A mental picture of the greenhouse effect", Theoretical and Applied Climatology, vol. 128, pp. 679-688, 2016. http://dx.doi.org/10.1007/s00704-016-1732-y
134 Dan DaSilva says:
“Every one of the many climate models over predicts the rate of warming and every one of temperature adjustments has either lowered long past temperature or raised the recent temperature.”
Except they dont. Five minutes spent reading about climate models shows thet havent over predicted a single thing. You are looking too much at short term trends influenced by natural variation.
And the temperature adjustments are not all in favour of global warming. In fact adjusted temperatures over the last 50 years are almost no different to raw data, for all practical purposes. Temperatures early last century were adjusted quite significantly, but the reasons are entirely proper.
It takes only a bit of reading to find this and I’m a lay person on climate change.
These things have been pointed out to deniers / sceptics hundreds of times but they keep on making their cynical posts.
It’s hard to not conclude they are either stupid, or simply attention seekers or trolls.
Dan dS, #134–
Er, no. Wrong on both counts. Where did you get this idea? It would be quite interesting to deconstruct the presentation that gave that impression, so links would be welcome.
https://www.realclimate.org/index.php/archives/2016/08/unforced-variations-aug-2016/
As you can see, current observations are well within the envelope of the ‘model ensemble’–as of August, quite close to the mean, actually.
And, from Karl et al., 2015:
http://science.sciencemag.org/content/348/6242/1469.full
“…it is also clear that the long-term trend would be significantly higher (0.085°C decade−1) (Fig. 2B) without corrections for other historical biases, as described in (26).”
IOW, the corrections mentioned as (26) had the effect of lowering the full-record warming trend from the afore-mentioned 0.085°C decade−1 to 0.068°C decade−1, or about 34%. Both versions are graphed in Figure 2b.
Just one instance; it’s not the only one, despite what WUWT et al would have you believe.
FWIW, reference 26 is this:
T. M. Smith, R. W. Reynolds, Extended reconstruction of global sea surface temperatures based on COADS data (1854-1997). J. Clim. 16, 1495–1510 (2003). doi:10.1175/1520-0442-16.10.1495
#137, Dan dS–
“How smart do I have to be to realize that if the proxy for temperature is going in opposite direction of actual recorded temperature history that some problems exist with the proxy?”
Let me answer that question with another. I presume that you are talking about the tree-ring record, is that correct?
If so, then my question is:
“What did Mann, Bradley and Hughes do in their 1999 paper to address the problem of tree-ring ‘divergence’, and why?”
Further question:
“Who was their main source in undertaking the strategy that they used?”
It’s kind of a cool story, actually. Do you know it? If not, can you find it?
DDS 149: On the human enhanced atmospheric fertilization of plant life (know as global warming by the omnipresent Earth Gaia religion) I would agree.
BPL: CO2 helps plant growth if and only if it is the nutrient available in least supply–Liebig’s “Law of the Minimum.” In nature, the actual nutrient available in least supply is more likely to be water. Since global warming spreads droughts, we can expect it to hurt agriculture, not help it.
Romain 146,
Your question has been asked and answered. All you do is repeat the same words, which is the sign of a troll to me.
You asked why we were confident that what is happening now is unprecedented. I tried to explain the thought process that leads us to that conclusion, which involves more than “a study”.
At this point, it sounds like you may have some bizarre misconception even about what the one “study” you keep mentioning is even measuring. Could you please explain what you mean– in complete, descriptive, sentences, quantitatively, what you mean by “resolution is 300 years at best”? Resolution of what.?
Pretend that you are a teacher explaining it to a student. That’s always the best way to test your understanding.
Dec 28 7:05 AM
153 Kevin McKinney “Let me answer that question with another. I presume that you are talking about the tree-ring record, is that correct?”
Yes, that is what I was talking about. I referred to it in a roundabout manner because of fear of censorship. One of my posts was replied by Dr. Mann and he asked me a question. My reply was tossed in the Bore Hole. It was not an attack just a reply to his question.
The moderator of this topic has allowed free discussion. I will read more on the “tree divergence” but my inclination is to be suspicious of proxies especially if they do not match known data.
> Wrong on both counts. Where did you get this idea? It would be quite
> interesting to deconstruct the presentation that gave that impression,
> so links would be welcome.
The copypasters don’t dare give the sources from which they are rebunking.
They draw from septic sources like the DailyMail or Vincent Gray at “Friendsofscience”
https://twitter.com/KHayhoe/status/804431252421906432/photo/1 patiently addresses some of the frequently rebunked nitwittery being promoted from Breitbart by the House Science Committee.
DDS 156: I will read more on the “tree divergence” but my inclination is to be suspicious of proxies especially if they do not match known data.
BPL: So is everybody else. Tree proxies are one of many proxies used to measure historical temperatures, and for most trees it works fine. A certain subset of North American trees started deviating about 1960, and people have been at work on that problem since it was noticed. But there are many, many other proxies than tree rings. Mann et al.’s “hockey stick” has been duplicated by fourteen other studies that I know of, some of them using no tree ring proxies at all. Google “paleoclimatology” for more details.
Zebra 155,
“Your question has been asked and answered. All you do is repeat the same words, which is the sign of a troll to me.”
Sorry if it seems this way, and thank you for trying to help me. I really can’t understand why people do this claim, as if it was a settled fact.
My last comment was for Nigelj, who claim there are studies showing the warming is unprecedented in the last 10,000 years.
Do such studies exist or not?
“Resolution of what.?”
Resolution of the reconstruction of the global average temperature.
Ok, I will try to explain the resolution problem as simply as possible:
1. The current warming is a delta in global average temperature of 0.7°C in a time of 100 years. Or take 0.9°C in 120 years.
2.The claim is that this warming of 0.7°C in 100 years or 0.9°C in 120 years is unprecedented in the last 10,000 years.
3.The study by Marcot et al 2013.
In average, the individual records have a resolution of about 120 years. When combined to get a global temperature reconstruction, there is an inevitable smoothing that precludes the study to capture any variability in time scale of less than 300 years.
So for example, and grossly, a 1.5°C warming in 150 years followed by a 1°C cooling in the following 150 years would be recorded as a 0.5°C warming in 300 years.
So this study is inconclusive regarding the claim of unprecedented.
I’ve read the discussions on this paper at the time, and the resolution issue was discussed, but, AFAIK, not settled. See here:
https://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/comment-page-3/#comments
A part of one of the in-line responses from Raypierre summarises the issue:
“What is at issue is whether there are any other mechanisms of centennial-scale variability that could cause a 1C or even a .5C spike. We know that the AMO can go a smallish fraction of that distance, and it’s hard to rule out on first principles that some kind of ocean variability might not be able to do something bigger in amplitude if you wait long enough. There’s no evidence that it can, and I myself find it hard to see how you could make the ocean do a centenniel scale uptick (a centennial scale downtick is easier, since there’s all that cold water you could conceivably bring to the surface). ”
You, Zebra, and others here, seem to be in line with this: because you “find it hard to see how you could make the ocean do a centenniel scale uptick”, therefore the upstick does not exist. Is this how strong the claim of “unprecedented” is?
Anyway, thanks for your time and help.
Well, I haven’t checked the RealClimate for a few months and _these_ are the pearls he have been missing ???
Dan DaSilva, 139:
“did you know that some climate scientists are as arrogant as to think that they can accurately model the earth’s climate?”
What make this great is that it comes from same Dan Da Silva, who a few days back illustrated the knowledge that allows him to pass judgement on “climate scientists”, by the following:
“Why is it that only the Carbon in CO2 is bad? Oxygen is contributing twice as much. I like carbon just as much oxygen, although I must admit that my need for oxygen is reinforced every breath I take. I tend to think as oxidizers as the more violent elements while carbon just wants to make friends.” Dan DaSilva, 98, 23 Dec 2016
Merry Christmas everyone! ;-)
===
Piotr
Romain 160,
If you had started with that we wouldn’t have wasted so much time.
You are confusing “unprecedented global warming”, which is happening now– anthropogenic increasing CO2 changing the global energy balance, with “natural variability of average global temperature”, which results from variable energy exchange dynamics within the system.
I thought this might be the case, which is why I kept at the “cause” issue. I see that you still don’t get the difference.
The “uptick” in question would be something like ENSO, a natural variability within the system. That’s not the same thing as what is happening now, so even if there were such (yes, highly unlikely) cyclical processes being “missed” by Marcott, the current situation is still unprecedented. The unprecedented comparison is to other cases where the global energy balance changed– how rapidly did the temperature go up or down in the transitions to and from ice ages, for example, or to some other case of energy balance change.
As to your misunderstanding of Marcott– think of it as a “moving average”. Let’s say we see (in the flat part, a few thousand years) and using an arbitrary number) a value of 15C with maybe a little wiggle of .1C. What would have to be the case if we are “missing” a rise of 1C?
Well, obviously, the temperature would have to be varying between 14C and 16C, correct? So, here’s the question: Would Marcott miss what is happening now, if it occurred in that “flat” time period? The answer is no.
If you would like to continue, please demonstrate that you understand why I say that, or why you disagree.
Also, I tried to reply earlier to your previous comment but apparently clicked the wrong click. Of course CO2 is a proxy for temperature. If CO2 concentrations increase, we are very confident that temps will increase. Unless you are challenging basic physics, this should be obvious.
R 160: 2.The claim is that this warming of 0.7°C in 100 years or 0.9°C in 120 years is unprecedented in the last 10,000 years.
BPL: If you use the Hadley Centre CRUTEM figures, the rise is 1.2 K over 166 years, so that defeats your whole argument.
R: In average, the individual records have a resolution of about 120 years. When combined to get a global temperature reconstruction, there is an inevitable smoothing that precludes the study to capture any variability in time scale of less than 300 years.
BPL: In what way does it do that? Show your work.
OK, Science has made great strides and helped average people immensely. There have also been spectacular failures that this post seems to ignore. The question is how can we improve science’s performance? The problem I see here is that some scientists see their role as apologists for science in order to defeat the “forces of science denial.” That’s not useful and perpetuates the status quo. I would really like to hear rasmus address the replication crisis and what can be done to address the huge waste of resources involved.
https://books.google.com/books?id=Wha4DwRa2wgC&pg=PA570&lpg=PA570&dq=journal+geophysical+research+oxygen+isotope+climate&source=bl&ots=awrxaOZH5r&sig=dxq-lmOsjLgcXqQxiLDApkReI8s&hl=en&sa=X&ved=0ahUKEwjMhNKgpqDRAhWHiVQKHdz9AYQQ6AEIMjAD#v=onepage&q=journal%20geophysical%20research%20oxygen%20isotope%20climate&f=false
Climate Since A.D. 1500
By Raymond S. Bradley, Philip D. Jones
David Young, I notice that when people talk about “spectacular failures of science,” they never seem to come up with any examples. Or when they do, what they actually have are failures of technology or scientific studies brought about by failure to rigorously follow the scientific method.
Want to improve science? Follow the scientific method.
151 – “It’s hard to not conclude they are either stupid, or simply attention seekers or trolls.”
It is largely willful ignorance. The reasoning goes like this.
I don’t like the solutions to problem, hence I will ignore reality and demand that the problem can not exist.
It is monkey thinking, and it is primarily seen in Conservative Ideologues because the solutions (reality), does not mesh with their world view of how things must work.
Alternatively it is seen in Conservative Christians who are well practiced at lying to themselves about angels, demons, heaven, hell and invisible space fairies.
Some will publicly state that it can’t be a problem because God gave the universe to us, or that God will save us. Others want to force God’s hands and advance his time table for the Tribulation.
“We don’t need to protect the environment. The second coming is at hand.” – James Watt, Secretary of the Interior, Reagan Administration.
BPL, Tamino addressed the “smoothing” issue R is rebunking, at
https://tamino.wordpress.com/2013/04/03/smearing-climate-data/
BPL @ 163 – surely you jest.
You expect to be able to stack a series of noisy time signals and maintain frequency content? 40 years of seismic processing experience made me laugh the first time I heard the claim of modern warming being unprecedented. Imagine having a plot of your average monthly temperature and then overlaying this years daily temperature. Normally in Perth this time f year the temp[erature only goes up 0.1 degrees per day, but today it went up 9 degrees!!!!
BPL,
For me, this is like the “free market” thing. I don’t think allowing these people to create/control the framing and language is the best approach.
With due respect to Tamino, nobody in the real world is going to be swayed by such arcane arguments. Is he right? Sure, but this is not an abstract statistics exercise. Why let that be the discussion, when we know most people will have no way to judge or interpret the outcome? It plays into the Denialist’s hands, as far as I am concerned.
As I pointed out in replying to R, Marcott would almost certainly have detected what is happening now had it occurred in the past, for obvious physical reasons, given the resolution claimed.
Also, a cyclical internal variation would have to be “just so” to be missed, and we know that there is no plausible physical mechanism to explain such a phenomenon.
Either scenario, in addition, would be likely to leave other, non-temperature signals– we can be pretty sure the mythical “precedent” did not result from CO2 going from 280 to 400ppm, for example.
Why do we continue to play their game on their field?
Woolard: “You expect to be able to stack a series of noisy time signals and maintain frequency content?”
That depends on whether the noise in the different proxies is correlated. If not, and if the proxies really are measures of the same signal, then in principal adding proxies will increase signal.
Rae @ 171 – no it doesn’t. You sampling frequency is hugely under nyquist.
BPL, 163
“If you use the Hadley Centre CRUTEM figures, the rise is 1.2 K over 166 years, so that defeats your whole argument.”
No it does not. Why do you think it does? I don’t even have to modify the example I gave: upsticks of 1.5°C in 150 years not being recorded.
“In what way does it do that? Show your work.”
It’s not my work, it’s the one of Marcot et al. And the 300 years come from their own answer here on Realclimate.
I don’t know the details about the quantification of the resolution, but having geographically distant records, each one having different resolution and accuracy in the dates as well as in the temperature reconstruction, its not surprising that you have smoothing.
In fact they even said than only 50% of the temperature variability is preserved at 1,000 years intervals…
See here:
https://www.realclimate.org/index.php/archives/2013/03/response-by-marcott-et-al/
Q: Is the rate of global temperature rise over the last 100 years faster than at any time during the past 11,300 years?
A: Our study did not directly address this question because the paleotemperature records used in our study have a temporal resolution of ~120 years on average, which precludes us from examining variations in rates of change occurring within a century. Other factors also contribute to smoothing the proxy temperature signals contained in many of the records we used, such as organisms burrowing through deep-sea mud, and chronological uncertainties in the proxy records that tend to smooth the signals when compositing them into a globally averaged reconstruction. We showed that no temperature variability is preserved in our reconstruction at cycles shorter than 300 years, 50% is preserved at 1000-year time scales, and nearly all is preserved at 2000-year periods and longer. Our Monte-Carlo analysis accounts for these sources of uncertainty to yield a robust (albeit smoothed) global record. Any small “upticks” or “downticks” in temperature that last less than several hundred years in our compilation of paleoclimate data are probably not robust, as stated in the paper.
Zebra, 162
“I see that you still don’t get the difference.”
You are right, I don’t see the difference.
The claim “unprecedented global warming” is a general one. You seem to back it up by categorising the warmings. Why? If there were a precedent global warming with an equivalent rate of increase in an equivalent time frame, that will make the claim wrong. Period. Why would you discard the precedent warming because of what caused it?
“Would Marcott miss what is happening now, if it occurred in that “flat” time period? The answer is no.”
How so? How do you get rid of the resolution problem?
“Of course CO2 is a proxy for temperature.”
Reference please? Proxy has a specific meaning. That a CO2 increase will create a temperature increase does not make it a proxy. That they are generally correlated neither.
Romain 174,
1) I didn’t “discard” anything. I am trying to answer your question, which was something like “why are you confident that there is no precedent”. The two things are different, so of course my reasoning is different for each. Why do you think it should be the same?
2) Repeating the term “resolution problem” and not answering my question, is, again, troll-type rhetoric. For the global warming case– temp goes up due to global energy increase resulting from CO2 increase, not internal variation– describe what the temperature plot would look like over say 1,000 years with our situation somewhere in the middle.
3) If “proxy” “has a specific meaning”, why don’t you just tell us what you think it is? Your inner-troll-rhetoric is showing when you don’t contribute to moving the discussion forward.
Keith Woolard, Pray, what is the Nyquist frequency for climate?
174 Romain “Why would you discard the precedent warming because of what caused it?”
Good question. So Romain where is and what is your precedent warming during the last 20,000 years or the last 10,000 years that was faster and higher than the present last ~150 years or even the last 50 years?
Go hard! Present your empirical evidence such a precedent warming exists. This should be easy and quite simple. Yes? :-)
Rei and Thomas (176 & 177)
You really don’t understand do you!
So you have a hugely variable noisy signal that you have sporadically sampled by proxy at a few random locations around the world at different times to each other using different methodologies. You then add them together and come up with smooth flat plot (surprise surprise). You then splice onto that an extremely highly sampled dataset where thousands of samples lie between just two points on the original. And you use that to suggest the current warming is unprecedented. If there is a single paleoclimatologist alive that believes the 10000 year reconstruction is accurate to with a degree everywhere I will eat my hat.
If I sampled HADCRUT4 at 120year intervals, I could make a trend anywhere from -2 to +4 degrees per century.
To say something is unprecedented you need to compare apples to apples
and specifically in answer to #176, if you are going to claim a change in 70 years, then you need to sample that waveform twice. So the reconstruction must be done with a minimum sample rate of 35 years for every input dataset
Keith Woollard,
“And you use that to suggest the current warming is unprecedented.”
Nonsense.
1) There are many reasons to suggest that the current rate of change of system energy is unprecedented in the last 10,000 years.
2) There are many reasons to suggest that there is not a periodic transfer of energy to and from the sampled environment (from and to an unsampled part of the climate system), of a similar magnitude in a similar time frame.
All of these precede and are independent from Marcott et al.
You appear to have much more background than Romain, so I will pose the same question to you in hopes of an actual answer:
If the current condition of anthropogenic CO2 changing the energy balance had occurred somewhere in the middle of that flat part, would it still be flat?
Zebra, 175
1) “the two things are different”: which “things”? Are you refering to natural warming versus (anthropic) CO2 driven warming? If so, we are running in circle, here, because I still don’t understand what it has to do with assessing if the current warming is unprecedented or not.
2)I’ve answered your question by re-stating the resolution problem. To be clearer: I think Marcott type temperature reconstruction could miss the rate of the present warming, yes.
The exercise you are proposing is a difficult and a sloppy one, as it implies filling the next 500 years.
For the low resolution records, they could for sure not record the sharpness of the present warming, even if their site follow the global trend.
For all the proxies, including the high resolution proxies: first, one would need to check the temperature trend at each of the proxy record site. Are they closely following the global trend? Maybe one of the sites is experiencing a cooling? Do you know if this has been studied/discussed already?
I can only remember I’ve checked Vostok some years ago, and the site was pretty much following the global trend. But it was obviously not the case in the past, because the quick swings you see in the record got smoothed in Marcott, meaning it can only have been regional and other records were flat or cooling at the same time.
3)For definition, see here: https://en.wikipedia.org/wiki/Proxy_(climate). So tell me, which climate sensitivity (equilibrium, transient?) to CO2 would you use as a correlation for your “proxy”?
Keith, I see the problem. I don’t believe that anyone is claiming that warming is unprecedented based solely on the reconstructions. The reconstructions do a pretty good job of giving us the magnitudes of the historical changes. However, if you are going to claim that those events took place on timescales of decades, then you have a problem. Either the precipitating events would have to be anomalously energetic or climate sensitivity has to be anomalously low. Also, the faster the event, the harder it is for organisms to adapt–and there are not instances of mass die-offs in the fossil record.
Keith, I do not claim the warming is unprecedented. I’m merely basing my comments on the existing peer-reviewed best practice science, some of which is summarized in the last several IPCC reports. If that is wrong then it should be corrected, imo.
So Keith Wollard where is and what is your precedent warming during the last 20,000 years or the last 10,000 years that was faster and higher than the present during the last 1750 – 250 years, 1850 – 150 years, or even the last 1965 – 50 years?
It’s a simple question. Present your empirical evidence such a precedent warming exists. This should be easy and quite simple (using existing accumulated data). Yes?
You may even track the CO2 records above 280ppm along the same plot. :-)
Keith Woollard:
Before you repeat your “but nyquist…” argument yet again, which would make sense if the time series were sampled at a fixed interval, you should probably read up a bit on how randomly-sampled time series do not have the same characteristics.
I suggest the following posts over at Tamino’s:
Sampling Rate
Sampling Rate, part 2
Once More
I’ll address Bob@184 first because it is fairly straight forward. Yes, I know to do an FT or an FFT requires a constant sample rate, and therefore there is an implied strict Nyquist frequency. However the same problem of resolution and aliasing occurs with non-uniform sampling. Even though we are not applying a transform, we need to be aware of the limitations of the sample rate used. Tamino’s logic is “look, you can see the signal” conveniently stopping the display before the next octave.
And I appreciate the fact that you have gone to the effort to spell my name correctly
And I will address the others here
Zebra @180 and Ray @182 – It certainly seems to me that the reconstructions are what people are using. The only other evidence I have heard is “we can’t think of a reason the temperature would increase that much” What other possible evidence could there be?
and as for Zebra’s slightly rephrased question – there is a very high probability that you would not see it. Think about what the proxies are measuring and where, and imagine you combine them from different periods over the last 20 years, and you did the same 100 years ago. There is really little point discussing this. I will let you believe there is signal between the sample points but I will stick to the maths.
And really Ray – Fossil records from the last 10,000 years??? Mass die-offs at the moments are from direct human intervention, not the 1 degree temperature change.
Thomas@183 – I have no evidence of previous equal temperature change, nor do I claim it. All I am saying is that we currently cannot know given the information at hand.
Romain 181,
“as it implies filling the next 500 years.”
Last chance. If you can’t answer such a simple question, the discussion is pointless.
You say “the resolution is only 300 years” and this is a “resolution problem”. OK, using simplified but reasonable numbers according to our current science:
We observe for a few hundred years a flat line at 15C with maybe +/- .1C wiggle. Now, CO2 starts to increase, and with it the actual global average temperature. Let’s say, for simplicity, that the actual temperature goes up 5C over 500 years, and that it is a straight line increase, of 1C per century.
So, what would the Marcott plot look like? This doesn’t require detailed calculation; I’m just trying to get a general idea.
1. Does the plot continue as a flat line at 15C, as before, for 500 years?
2. Is it a straight line with a different slope?
3. Is it a curve shaped like an “S”?
4. What is it?
Repeat: We start with that straight line, +1C per century, as the actual temperature, and then we apply the Marcott “resolution problem”. What happens?
Thomas, 177
“Good question.”
Thanks, but you did not answer to it.
I don’t have any evidence that such a global warming has ever existed. all we have is sparse proxies…
But you are certainly aware that the absence of evidence is not the same as the evidence of absence?
Can I ask you in return what is the evidence that such a warming could not exist?
Could you or someone direct me to a study (or blog post or whatever) that explains (with quantifications) why natural fluctuations of oceans cannot lead to an increase in surface temp similar to the one we are experiencing?
Thanks.
Zebra,
The future warming that is in your head most certainly is unprecedented, and it would be recorded by a Marcott like reconstruction, I have little doubt.
But you will admit that using the future to explain the past is…well…unusual!
Keith,
I think that it should be uncontroversial that in order to get such a rapid rise over a short period, then either you have to have a massive influx of energy (in which case, I’ll ask you what the source might be), or sensitivity must be VERY large (in which case, we are likely already in the soup). Pick one.
Keith Woolard 186,
Your response to me makes no sense. Proxies 100 years ago, 20 years ago? What are you talking about? This is about the Marcott plots over 10K years, not the recent past where the proxies are questionable if not useless.
Perhaps you could answer my question at 187 using your “maths”?
#186 Keith Woollard re “I have no evidence of previous equal temperature change, nor do I claim it. All I am saying is that we currently cannot know given the information at hand.”
Thx for the straight reply Keith. It’s rare and commendable. Could we flesh out your reasoning on this?
I can easily accept that “an absence of evidence, does not equal evidence of absence.” Would you agree with that?
I can also accept the philosophical idea of the elephant and the blindfolded wise men trying to work out what they are touching. ie drawing conclusions based on insufficient/partial evidence can easily lead to error. I think that Proxies are very much like that. And blind spots due to natural bias happen all the time, even in science.
If I have this right, then your opinion is that the ‘evidence/info’ based on ‘proxies’ for Temp going back 10-20K years is insufficient to logically or reasonably conclude today’s temps are ‘unprecedented’ in this time frame? (If my assumptions are ever wrong please correct me.)
So if I assume you do accept today’s data for current temps and other warming evidence is valid and reasonable, then how far back in time do you accept that these temps are unprecedented Keith?
iow how far back do you consider the scientific evidence is robust enough to draw a reasonable logical conclusion for unprecedented temp increase above the “avg. norm”?
And re the Proxies used to date, is your opinion that they are merely insufficient evidence overall, or is it a matter that you think there is some basic flaws in the methodology used to establish the data of those proxies and or convert those proxies into accurate enough Temp numbers?
I’m genuinely curious. Thanks.
‘Dan DaSilva’ didn’t last long. #109Dan DaSilva says: “I would like to thank the moderator for allowing me to enter into this sheltered forum.”
versus 27 Dec 2016 https://www.realclimate.org/index.php/archives/2004/12/the-bore-hole/comment-page-35/#comment-665920
Another quitter unprepared to back himself or expand his knowledge and awareness or handle the heat of some challenging self-reflection. Oh well.
Keith Woollard @185:
You seem to be under the illusion that Fourier Transforms can only be applied to uniformly-space data. This is not the case. Try this Wikipedia article. It starts by saying
Or, read fully the posts that I provided in #184, where Tamino specifically does Fourier Transforms on non-uniformly-spaced data.
Assertions that something can’t be done are not very convincing against examples where it has been done. With randomly-spaced data, it is possible to identify cycles with periods smaller than the smallest interval between individual samples. Again, read fully the links I gave previously.
Zebra,
Your statement is ludicrous. Your original question was “If the current condition of anthropogenic CO2 changing the energy balance had occurred somewhere in the middle of that flat part, would it still be flat?”
I answered that. What you are asking now is to try and imagine the next 400 years and what that might be like. There are 100 unknowns and if you think you can predict the future go and join a religion. You have answered your own original question….. flat +/-1 1degree sampled at 120 years and smeared across multiple proxies = indecipherable
Romain 189,
“The future warming that is in your head most certainly is unprecedented, and it would be recorded by a Marcott like reconstruction, I have little doubt.”
Excellent; we are making progress. So now describe, for the same 500 year time period, an example of the warming that would not be recorded.
Re: Thomas 193, on the Dan DaSilva episode
One can still appreciate the sheer chutzpah of the guy who after posting such gems of scientific insight as:
“Why is it that only the Carbon in CO2 is bad? Oxygen is contributing twice as much.” (Dan DaSilva, Dec 23, this thread)
three days later delivers the I-am-a-denier-and-proud-of-it speech and assures readers:
“I deny that I am ignorant.” (Dan DaSilva, Borehole, Dec 26)
188 Romain says: Thomas, 177 “Good question.” … Thanks, but you did not answer to it.
Correct. Your questions are not my responsibility or problem. What do you think the answer is? That’s what should be important to you.
I don’t have any evidence that such a global warming has ever existed. all we have is sparse proxies…
So you have no idea / guess about warmer temps during the Jurassic etc? That’s pretty odd imo. Maybe a 6000 year old earth is a possibility too then. We have no hard evidence that Hitler ordered the holocaust either. Nothing in writing, only rumour, hearsay, and innuendo which could be called Proxies, right?
These are metaphor/analogies to help you think through your own processes to date. Logical thinking either is or isn’t. There is no halfway house. :-)
But you are certainly aware that the absence of evidence is not the same as the evidence of absence?
Oh yes very much so, I know that one in spades from direct personal experience. I also know how it can be misused in sophistry arguments too. The key here is what actually is the evidence and the facts that are known. But reason should not be left on the table when there are gaps in ‘data’ either. A liar is a known liar even when you lack the evidence for the most recent utterance by a liar. ….. “reason” Romain. “Dialectic” Romain.
Face facts, you have ZERO evidence the past 10-20K was in fact warmer than currently suggested by the scientific proxy data …. you have nothing, science has something. By all means remain unconvinced, but if you image your doubts are convincing evidence for anything well see above “reason” “dialectical” “logic” “data” “observations” and “an absence of evidence” is still an absence of evidence Romain, and you got ZERO of it.
Be a critic all you wish but you’re delusional if you think anyone has a single reason to recognize you as an expert in the field. Anyone can criticize and complain .. anyone. You’re the one who lacks credibility, not the proxy derived info by genuine credible scientific experts across decades.
Like mate, just because you can doubt and question doesn’t mean you have some god given natural right to receive an answer. Think about that for a while.
Can I ask you in return what is the evidence that such a warming could not exist?
Sigh … can’t prove a negative Romain. Try harder. Think man, think. :-)
Could you or someone direct me to a study (or blog post or whatever) that explains (with quantifications) why natural fluctuations of oceans cannot lead to an increase in surface temp similar to the one we are experiencing?
No. As far as I know such studies do not exist. But there are thoudands which point out how natrual variation of ocean temps could NOT cause the current global warming. But you seem to not like those.
Can’t help you. “God helps those who help themselves” it is said.
Thanks.
No worries. You are welcome. I do understand how confusing this whole business is for most people. It’s not a crime to question things, but the onus is on you to make wise choices about who you trust and why. No one can help you with that. Good luck.
Yes Bob, I know you can transform with non-evenly spaced samples, I have been signal processing for a while. Read my 185 again. We aren’t doing a transform on the data, We aren’t looking for periodicities like Tamino imagines we are. The only reason I brought up Nyquist is it is a simple concept that explains the limitations of sub-sample interpolation.
Let me re-iterate – you would not see a sub 100 year blip in the proxy record. Using Tamino’s example of spotting 60Hz on a 0.2s samplerate, then using the proxy record, we should be able to see 12 times the Nyquist’ish frequency. That puts the 120 year sampled stuff at 10 year. I challenge someone to find the 11 year solar cycle in the Marcott data. If you can’t, then Tamino is wrong or the proxy record is wrong or both
Thomas @192.
This whole discussion is about temperature change, not temperature. The issue here is only about the fact of whether the current rise could have occurred in the past.
The low frequency component (or lack thereof) in the proxy record is a whole different discussion
And to answer your final question, and at the risk of opening a new can of worms – how far back do we have meaningfully precise globe-wide temperature data – 1979 (I’ll now go and run for cover)