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kishoreragi at 14:48 PM on 19 September 2013Models are unreliable
Roger D
I don't want to go predict big things right away with incomplete models, but I want to eloborate what I wanted to inform here.
I have given this analogy because there is a need to understand each and every animal (here it is physical process) is related (friendly/hostile, here for climate, how processes are intricately mixed- diminishing/strengthening) on forest variables (We can choose any variable here) on specific part of forest(Any region of the world). So that little by little, we can understand about the comple forest and their inter-relation.
My main point is that the science has progressed much further, but in wrong path. The simple fix for this is to make the system simple and see the intricacies among the processes, leaving the comparision with observations, on regional climate variables so that in the FAR future, we may be in a position to see the BIG picture like AGW without hesitation from anybody (skeptics/supporters) and with clear understanding. As far as I understand(ofcourse I am still reseach student), there is no other way as climate system super complex !!!
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r.pauli at 14:10 PM on 19 September 2013The 5 stages of climate denial are on display ahead of the IPCC report
I am reminded of the word 'confabulation'. Tremendously rich and useful - important in abnormal psychology..
https://en.wikipedia.org/wiki/Confabulation
The phrase "climate confabulation" Explains much nicely.
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John Hartz at 14:03 PM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
@hank #15:
Do you happen to know what percent of Australians currently believe that AGW is happening now?
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Rob Honeycutt at 13:50 PM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
Now that one is disturbing. But it's going to bite them in the butt long term, I think.
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hank_ at 13:35 PM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
@ Rob #14
Joe Nova's perceived "sea change" has alot to do with the major changes in the Aussie governments. Labor was defeated in a historice rout. The new leadership is promising to dismantle the hugely unpopular Carbon Tax and are already closing down Climate related departments everywhere.
It's not just a push ahead of AR5.
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Rob Honeycutt at 11:59 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
John... My point was more that, these are people who have continually received lots of exposure in the media. Nova seems to think this is some sort of sea change. The sea change is her wishful thinking. It's merely a coordinated effort ahead of AR5.
What Nova sees as a sea change is likely to get clipped pretty severely with the release of AR5.
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Hockey stick is broken
Phronesis - "McIntyre and McKitrick purported to refute/debunk a specific paper -- the Mann 1998 paper... as far as I can tell, McIntyre and McKitrick were right in their criticism of that particular Mann paper" Unfortunately for your argument, they utterly failed to make their case.
M&M's several papers on the subject have been at the center of numerous peer-reviewed refutations (five of them listed here), with numerous errors and erroneous claims pointed out at RealClimate, including critical failures to apply PCA selection rules to identify significant components; an error that alone invalidates their work. Similar errors in PCA selection (which would have distinguished invalid noise-generated hockey sticks as insignificant) and a rather amazing amount of cherry-picking in their 'red-noise' model are discussed on Deep Climate, notably with an unconventional 'red-noise' model that actually was derived from the proxies (rather than a theoretic red-noise spectra), and therefore included the 'hockey-stick' - no surprise that they found it in their 'noise'.
The M&M critcisms of Mann's work are completely invalid, on various methodological grounds.
Is MBH1998 without flaw? Hardly - it's the initial paper in the field applying PCA and machine learning techniques to multi-proxy climate data, and as such is rather rough around the edges. Their centering method is arguably not the best available, additional proxies and further clarification of then-existing proxies have improved the data, and there are reasonable arguments for different combinatorial and statistical techniques.
But methodological issues with MBH1998 don't invalidate the general conclusions, that recent temperatures are the warmest in the last 1000 years. And many papers, many reconstructions, looking at the issue come to the same conclusions.
At this point I see (IMO) unsupported objections raised against MBH1998 to be a clear identifying marker of someone in climate science denial.
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John Hartz at 11:04 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
@Rob Honeycutt #12:
The "major push" by climate deniers is not a figment of our imagination. The international propaganda campaign is documented in detail in:
Ahead of IPCC Climate Report, Skeptic Groups Launch Global Anti-Science Campaign by Katherine Bagley, InsideClimate News, Sep 18, 2013
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michael sweet at 10:47 AM on 19 September 2013Hockey stick is broken
Phronesis,
Are you talking about science or public relations? I will grant you than Mann and McIntyre disagreed about how to do the analysis. Mann thinks he was correct and McIntyre thinks Mann was incorrect. This issue has been resolved by collecting more data and redoing the analysis in a way that everyone agrees is correct. When that was done it was found that Mann was correct in his interpretation of the data. How does the noise that McIntyre continues to make relate to the data proving that Mann was correct all along? When extensive reanalysis and massive amounts of new data confirm the original finding that means Mann was right and McIntyre was incorrect all along.
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Phronesis at 10:02 AM on 19 September 2013Hockey stick is broken
Hi all. The framing of this page is erroneous. The "skeptic argument" and "what the science says" do not refer to the same issue.
McIntyre and McKitrick purported to refute/debunk a specific paper -- the Mann 1998 paper. That is all. Their debunking (if it was truly a debunking, which it appears to be) stands. It's not refuted by all the other, later research that reaches similar conlcusions as Mann.
If the point here is to say that the hockey-stick-is-bogus argument is wrong because of all the other evidence, that's fine. But as far as I can tell, McIntyre and McKitrick were right in their criticism of that particular Mann paper, on various methodological grounds.
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supak at 08:55 AM on 19 September 2013Patrick Michaels: Cato's Climate Expert Has History Of Getting It Wrong
OK, I've managed to get Michaels to publicly bet with me. I basically had to call him out in the comments at Roy Spencer's blog to do it, but...
http://www.drroyspencer.com/2013/09/pat-michaels-bets-on-25-years-of-no-warming
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Roger D at 07:35 AM on 19 September 2013Models are unreliable
kishoreragi at 17:00 PM on 18 September 2013 9 (found in What's causing global warming? Look for the fingerprints)
Your “a forest is like a climate model” analogy would benefit if you could identify the critical variables omitted from the models or issues with how climate models utilize them.
Yes, there are a lot of different animals moving around in a forest. Yes, modeling everything going on in a forest would require understanding how sensitive each thing is to changes in each other thing. But it’s not a valid analogy to just list some of the different things going on in a forest, and then jumping straight to the insinuation that climate models omit critical features. In short, you don’t provide any solid rational that climate models are not useful with respect to predicting changes in climate.
Moderator Response:[JH] Thank you for responding to kishoreragi on this thread.
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Rob Honeycutt at 05:03 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
Actually, I think JoNova is engaging in a bit of wishful thinking. It's not like they're getting any more airtime than they have for the past decade. These are all people who have published hundreds of OpEd and articles trying to reject AGW.
They're currently in a major push in advance of AR5, essentially because they know the key phrase is going to say that AGW is now "extremely likely." And that's coming from a body that is, by design, presenting a watered down version of the science.
It's interesting to read through the comments on her site. I'm sorry but they're (like her) just not a very bright bunch.
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Esop at 04:35 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
The deniers could not resist painting themselves into a corner with regards to this years uptick in minimum extent. The great thing about that is that the mainstream media will be all over them, exposing their failed 2013 predictions of lasting recovery when we break the 2012 record (likely some time before 2016). Then pigs will fly.
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John Hartz at 03:10 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
@ hank #8:
On the other side of the coin, there are many MSM outlets who stive for objectivity when reporting on climate change matters -- see recent postings of the SkS Weekly News Roundup for a sampling.
What goes on inside the bubble world of Jo Nova and her ilk matters little in the real world where the vast majority of people live.
At the end of the say, it's pulbic opinion that matters the most. That is the metric we need to focus on.
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Latest myth from the Mail on Sunday on Arctic ice
hank_ - It's my impression that 'skeptics' (aka climate science denialists) are currently blitzing every venue they can reach in anticipation of the IPCC AR5 report. I would consider this due to their (quite justified) fears of being dismissed.
A rather significant difference between the current situation and, for example, the 2007 AR4 release is that there are now many in the media who recognize issues of false balance and lobbyists (see, for example, Fareed Zakaria pushing Pat Michaels to admit that 40% of his income is supplied by the petroleum industry). Five years ago that kind of reporting clarity was not to be seen.
We'll have to see how things play out, but it is my perception that the 'skeptics' and their myths are losing media traction no matter how hard they pedal (or peddle)...
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hank_ at 01:25 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
Here's the thing, IMHO. We might have won this small battle, here, (with a video that many will not see), but we may be losing the mainstream media war.
See this article from Joe Nova (prominent Aussie skeptic).
joannenova.com.au/2013/09/skepticism-goes-mainstream-a-tipping-point/
Many may not like what she is saying but she has a valid point. Skeptics are getting airtime on 'big stages' so to speak, WSJ, Washington Times, Finacial Post, Daily Mail, etc. We can laugh at them and call them deniers but is the "rebuttal" message really getting out there as strongly as the skeptic talking points?
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Jubble at 00:36 AM on 19 September 2013Latest myth from the Mail on Sunday on Arctic ice
Jim @ 5 - I'll give it a go. "Some" experience with the PCC would be strictly true but a little misleading, ironically.
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CBDunkerson at 23:52 PM on 18 September 2013Latest myth from the Mail on Sunday on Arctic ice
Jim & Jubble, anything which can be done to hold reporters accountable for false reporting should be pursued.
I have long felt that this is the biggest problem facing the world today. The strength of the global warming denial bloc is just one of the many problems caused by the fact that there are 'journalists' reporting from alternate realities and no way to stop them. What is 'true' has become a matter of personal opinion because there are no consequences for vigorously promoting fiction as 'fact'. People follow the 'news' they want to believe and reject contrary reporting as 'biased'. Without some final arbitration of actual truth this can go on indefinitely and prevent any kind of real progress... because large portions of the population are making decisions about the 'best course of action' based on fiction.
I wish there were ways to get more of these issues into court. Michael Mann's defamation suit is going well precisely because lies don't usually work in the legal system (poltical rulings of the SCOTUS and some other higher courts notwithstanding). If there were a way to sue Rose and the like for 'false reporting' they wouldn't have a leg to stand on, but usually it seems like all you can do is complain to the 'news' organizations that hired them to lie in the first place. Even where things like the UK Press Complaints Commission exist, they always seem to be nearly toothless self-regulation. The very real need for 'freedom of the press' to print unpopular opinions has unfortunately been perverted into 'freedom to lie'.
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Jim Hunt at 23:40 PM on 18 September 2013Latest myth from the Mail on Sunday on Arctic ice
Jubble @4 - If you have some experience with the PCC would you mind getting in touch? We're in the throes of making such a complaint as we speak! There's a contact form on the site linked to @2. Perhaps we might compare notes and then mutually develop such a resource? TIA
In the meantime here's our very own video hot off the presses down here in not so sunny South West England. We rather hope it will prove to be music to the ears of David Rose and his ilk!
The Great White Con - Episode 1 -
CBDunkerson at 23:26 PM on 18 September 2013Models are unreliable
Given that climate models can closely approximate past climate, I'd think the onus is on 'skeptics' to show some reason why we should assume that they will not be equally accurate for future climate.
Just saying, 'there are too many factors involved to ever model climate' doesn't cut it given the established reality of models which already do successfully match past climate. Heck, we even know most of the causes of short term variation... such that if you plug major volcanic eruptions, variations in solar output, ocean cycles, and other such 'unpredictable' factors into model runs of past climate they then match not only the long term trends, but even the short term fluctuations around the trends. That's shockingly accurate for something which is supposedly 'impossible'.
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Models are unreliable
Kishoreragi, to add to Michael's comment: that is the way general circulation modeling is done. The Earth itself is one big experiment, and it has been well-demonstrated that the minor variables vary within certain ranges and rarely, if ever, end up leading global or even regional climate by the nose long enough to significantly alter major elements of general circulation. There is a strong tendency to regress to the mean, and the mean is driven by the major elements of the climate: continental drift, orbital variation, vulcanism, solar output, collision with significant extra-terrestrial objects, and, now, artificial enhancement of the greenhouse effect. Everything else is a feedback: something that reacts but is unlikely to change on its own -- biosphere (with rare exceptions), snow/ice albedo, ocean carbon cycle, clouds, water vapor, natural greenhouse effect, etc. Feedbacks vary and are integrated in different ways, but they regress to the mean of net forcing, with minor temporal variations driven primarily by ocean thermal capacity.
Thus it's a little inaccurate to describe the climate system as comprised of components that vary but are all of equal or near-equal power in shaping the future of the system. And, in addition to the major forcings, modeling does take into account many of the major and minor feedbacks. Of course, in the short-term (months to years), the interplay of major and minor feedbacks can produce significant but temporary anomalies, but the resonance of those anomalies across the long-term trend is ultimately insignificant. Arctic sea ice (ASI) is a great example. ASI is never, with all forcings stabilized, going to vary strongly and consistently to the extent that a glacial cycle is initiated. Only orbital or solar variation (or a one-timer) can do that (partially through the mechanism of snow/ice albedo feedback).
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What's causing global warming? Look for the fingerprints
Ok, JH - copying the comment over now.
Moderator Response:[JH] Muchas gracias.
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What's causing global warming? Look for the fingerprints
Kishoreragi, to add to Michael's comment: that is the way general circulation modeling is done. The Earth itself is one big experiment, and it has been well-demonstrated that the minor variables vary within certain ranges and rarely, if ever, end up leading global or even regional climate by the nose long enough to significantly alter major elements of general circulation. There is a strong tendency to regress to the mean, and the mean is driven by the major elements of the climate: continental drift, orbital variation, vulcanism, solar output, collision with significant extra-terrestrial objects, and, now, artificial enhancement of the greenhouse effect. Everything else is a feedback: something that reacts but is unlikely to change on its own -- biosphere (with rare exceptions), snow/ice albedo, ocean carbon cycle, clouds, water vapor, natural greenhouse effect, etc. Feedbacks vary and are integrated in different ways, but they regress to the mean of net forcing, with minor temporal variations driven primarily by ocean thermal capacity.
Thus it's a little inaccurate to describe the climate system as comprised of components that vary but are all of equal or near-equal power in shaping the future of the system. And, in addition to the major forcings, modeling does take into account many of the major and minor feedbacks. Of course, in the short-term (months to years), the interplay of major and minor feedbacks can produce significant but temporary anomalies, but the resonance of those anomalies across the long-term trend is ultimately insignificant. Arctic sea ice (ASI) is a great example. ASI is never, with all forcings stabilized, going to vary strongly and consistently to the extent that a glacial cycle is initiated. Only orbital or solar variation (or a one-timer) can do that (partially through the mechanism of snow/ice albedo feedback).
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franklefkin at 22:52 PM on 18 September 20132013 Arctic Sea Ice Extent Prediction
While the max extent in the spring is not as important as the min, it would still be interesting to see people's predictions for that. Is SkS going to do something like that? Is there any chance of Mr. Robinson updating his spiral graph?
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Jubble at 21:42 PM on 18 September 2013Latest myth from the Mail on Sunday on Arctic ice
I have an idea. Would it be a goer if this website or another provided the easy where-with-all for people (including myself) to make an official complaint each time a factually inaccurate, misleading and/or biased article appears in a national newspaper (whichever nation)? I've made a few complaints to editors and to the UK Press Complaints Commission (as a UK national) and would find it much easier if there was a set of text available in the appropriate language for me to use.
That way the number of complaints could be increased, the complaints would be more effective, they could be tracked for success ratios (e.g. better to make a lot of complaints about different specific issues relating to an article, or to make a single complaint about the whole article describing each error?).
If this sounds like a good idea, I'd be happy to help set it up, including contacting other organisations such as the Climate Reality Project, to help make it happen.
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michael sweet at 19:36 PM on 18 September 2013What's causing global warming? Look for the fingerprints
Kishoreragi,
Since you are a novice why do you suppose professoinal scientists who dedicate their lives to making climate models would overlook such basic steps as your example? The models are adjusted so that different processes are modeled appropriately. Your analogy to a forrest is simply a way to avoid having to point to a specific problem with the climate models. Please provide an example of a problem with resolution in a climate model. If an example cannot be provided, with all the "auditing" that skeptics do, that suggests that your objection is simply an argument from ignorance. Just because you do not know how to model climate does not mean no-one knows how to make suitable models. Read some of the modeling threads here or at Real Climate and you will be more informed.
Moderator Response:[JH] Let's move this discussion to a more appropriate thread, i.e., How reliable are climate models? Thank you.
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John Mason at 18:09 PM on 18 September 2013Latest myth from the Mail on Sunday on Arctic ice
Superb - I liked the London temperatures analogy!
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Jim Hunt at 18:02 PM on 18 September 2013Latest myth from the Mail on Sunday on Arctic ice
Please forgive me for continuing to flog this particular dead horse, but an interview with Wieslaw Maslowski from December 2007 which reveals the sort of things he was actually saying at that time can be heard here:
http://greatwhitecon.info/2013/09/shock-news-why-isnt-the-arctic-ice-free/
Needless to say Prof. Maslowski's views were not accurately reported by David Rose in the Mail on Sunday. Hence we are attempting to persuade the Mail to recant this and the many other inaccuracies they have recently put into physical and virtual print with the aid of the UK's Press Complaints Commission. How far we'll get remains to be seen, but please feel free to inform any of your friends and acquaintances who might be interested in following the developing story. -
kishoreragi at 17:00 PM on 18 September 2013What's causing global warming? Look for the fingerprints
This is my recent comment at http://jrstalker.wordpress.com/2010/02/28/the-difficulty-in-quantifying-the-extent-of-global-warming-or-cooling in agreement with Dr. James Stalker. Here I want to report ...
Simple example to explain James Stalker’s thought of how erroneously climate models are built.
Lets assume a forest is analogous to a climate model. Like forest has many living things from insects to wild animals, climate models have many physical processes having local scale to global scale, and time scales of fraction of seconds to centuries.
Some insects have foot-steps of a fraction of micro-meter and other animals have of few meters. Moreover, few animals are brisk and other are slow. That means, different animals have different temporal and spatial steps. For example, if we are to model a forest with all kinds of living things in the forest, we need to take all these steps (temporal and spatial) of all living things into account. For example, first lets assume we have chosen spatial resolution of 10 meters and time step of 2 sec. Lets imagine how reliable these resolutions for all living things in a forest. It may be right for deer but, can an ant jump 10 m in 2 sec? In the same way, each climate process analogous to each living thing in a forest, has different temporal and spatial time step. Hence, if we are to model climate, we need to take all these steps ( temporal and spatial) of all physical processes of climate into account.
If we don’t take these suitable resolutions(temporal and spatial) for various variables, we are going to ask an ant to jump few meters in second or two, and a deer to rolling on the floor and many more clearly visible blunders with animals. At the present situation, climate community is asking the models to do mistake as this forest model example, and artistic science is saying 97 % community is in agreement with anthropogenic global warming !!!
I am a novice in climate research. So, lease let me know if any climate model takes care of such things in building model so that we can rely on them. But, from my perspective, the utility of such model are only to understand better about climate system intrecacies with a lot of uncertainty ...
Moderator Response:[JH] Let's move this discussion to a more appropriate thread, i.e., How reliable are climate models? Thank you.
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Deco79 at 16:16 PM on 18 September 2013Latest myth from the Mail on Sunday on Arctic ice
Staggering stupidity. I bet Mr Rose will be the first to write an article on the "infinite" recovery of ice once we do have an ice free summer.
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Doug Hutcheson at 13:42 PM on 18 September 2013Global Warming’s Missing Heat: Look Back In Anger (and considerable disbelief)…
And so far, we’ve only experienced 0.8 degrees C of warming. Who in his right mind would dare suggest that 1.5 degrees of warming is safe?
Which is why I puzzle over the much-touted 2°C 'target' set by politicians. That amount of warming averaged across the biosphere means some places will get even warmer, some will be more static and some will cool. I have yet to read a credible argument showing how 2°C average warming will be an improvement over current temperatures, let alone how ocean acidification, due to concomitant CO₂e level increases in the atmosphere, will be a boon to terrestrial life.
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Doug Hutcheson at 13:15 PM on 18 September 2013Arctic sea-ice 'growth', a manufactured IPCC 'crisis' and more: David Rose is at it again
As a simple soul, I am constantly discouraged by the egregious disinformation presented by opinion-leaders who obviouslt know better. David Rose is of that ilk, as is Tony (Climate Change Is Crap) Abbott. Being a Rhodes scholar, Abbott is smart enough to understand the evidence, leaving me to surmise he knows perfectly well we are facing a climate crisis and is deliberately following a contrarian path.
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Tom Curtis at 10:18 AM on 18 September 2013What's causing global warming? Look for the fingerprints
GFW @8, we should distinguish between fingerprinting the rise in CO2 levels as anthropogenic (which can be done by carbon isotopes), and fingerprinting the rise in temperatures as being caused by increased greenhouse warming which cannot). I will grant you that SkS discussions of the topic often fail to distinguish this point, but never-the-less we shoud do so.
Further, the fingerprinting above is not "model based" in any except the most trivial sense. Any scientific theory is a model. It specifies certain empirical relationships between some measurable quantities and some other measurable quantities. In some theories, the models are very simple, and can be solved algebraicly with linear equations. Others are more complex. As it happens, the subject matter of climate science is so complex that detailed predictions can only be made by large, complex computer programs. Use of such programs to determine what the theory predicts, however, is no different in principle than using Newton's second law of motion to determing the force applied to an accelerating body.
The denier objection to computer models is, fundamentally, an insistence that the predictions of climate science be kept to the level of handwaving, ie, the only level at which their "predictions" can appear to survive empirical tests.
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K.a.r.S.t.e.N at 09:44 AM on 18 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
Icarus, the constant aerosol forcing ramp up is extremely unlikely. In fact, this is reflected in the Meinshausen-Forcing which is more or less the basis for the upcoming AR5. So yes, with GISS aerosol forcing, the sensitivity might be too high. On the other hand, the GHG forcing is on the high(er) side in the GISS forcing data. Some counterbalancing here, but I am afraid we are going to run into the next issue right away: The so-called effective radiative forcing concept. Way beyond what I can explain right now, but maybe something we get to hear more often very soon (see Forster et al. 2013 for more).
You are absolutely right regarding Hansen et al. 2011. It is certainly an interesting effort, a very interesting one to be sure, but I am inclined to think that the models have more trouble to get the ocean response right, rather than they are wrong regarding the aerosol forcing. My argument is mainly based on the latest developments on the "OHC-front", i.e. the results presented in Balmaseda et al. 2013. If true, they contradict Hansens assumption of a lower planetary imbalance in the last decade, which in turn suggests that the slow response function (effective deep ocean mixing) is closer to the truth (corresponding with a more plausible aerosol forcing). Given the current ENSO state, I'm hardly pressed to think that his notion of "[too] excessive deep ocean uptake of heat" (with respect to GISS modelE-R) might be wrong after all. What I heard from (some) ocean modellers recently, seems to point in a similar direction ... corroborated by the simple fact that the model response to the forcing over land is surprisingly good, while all the discrepancies are restricted to the ENSO region as well as the circumpolar southern oceans. Hoprefully, Fig. 2 from van Oldenborgh et al. 2013 helps to illustrate what I just said:
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scaddenp at 09:39 AM on 18 September 2013Medieval Warm Period was warmer
"My interpretation of D'Anrea's studies is that he believes in present day CO2 induced global warming."
Meaning what? That therefore his data must be wrong?
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What's causing global warming? Look for the fingerprints
Noting above the commenters who want to talk about the reliability of models, I think the article should mention that model-based fingerprinting is complementary to basic physical fingerprinting like carbon isotopes. Of course one has to accept that CO2 is a GHG to begin with for any of it to make sense. :/ -
spoonieduck at 07:46 AM on 18 September 2013Medieval Warm Period was warmer
I agree that the few barley grains found could have been imported. It is logical that the earliest Vikings would have experimented with cereals. These experiments might well have failed given the short growing season both then and now. Henrickssen, however, believes that these grains were locally harvested.
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spoonieduck at 07:38 AM on 18 September 2013Medieval Warm Period was warmer
My interpretation of D'Anrea's studies is that he believes in present day CO2 induced global warming.
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michael sweet at 05:58 AM on 18 September 2013Medieval Warm Period was warmer
Spoonieduck
Since you did not link your study I searched D'Andrea et al and found this study published in May 2012. It studies lakes in Svalbard, which is about as close to Greenland as Ellesmere Island. Here D'Andrea says:
"We find that the summer warmth of the past 50 yr recorded in both the instrumental and alkenone records was unmatched in West Spitsbergen in the course of the past 1800 yr, including during the Medieval Climate Anomaly, and that summers during the Little Ice Age (LIA) of the 18th and 19th centuries on Svalbard were not particularly cold, even though glaciers occupied their maximum Holocene extent."
The past 50 years are the warmest in the record. Many more crops are currently grown in Greenland than were attempted during the Viking settlements. The original settlers were hunters and not farmers. Greenland was never full of trees. A few barley grains in a midden could have been imported. They could grow barley today but it is cheaper to import from Denmark.
You only referenced one study. The others you describe without referencing or linking. How can I check what you say the studies claim? When I read DeAndrea et al 2011, I do not see the claim that the weather in 1100 was similar to today in Greenland. I see that it was warmer than earlier but no reference to current temperatures. Direct links allow me to read the study also.
Your assertion that since Greenland was named "Green" that it was warmer in 1000 AD than it is now is incorrect.
Moderator Response:[JH] I deleted your duplicate post of this comment.
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What's causing global warming? Look for the fingerprints
LandyJim - I would suggest reading through the Models are unreliable thread, followed by How do Climate Models work, and if you wish to commenting there.
Long story short - climate models are based on physics, fed forcings, and progress from there. Neither global nor regional observations can be generated from those physics unless anthropogenic forcings are part of the input.
I'll note that claiming that major factors '...may have been overlooked or simply ignored as an "inconvenient truth"', without evidence, is rather contrary to the"No accusations of deception" portion of the site Comments Policy.
Moderator Response:[JH] Let's move this discussion to a more appropriate thread, i.e., How reliable are climate models? Thank you.
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Roger D at 05:30 AM on 18 September 2013Medieval Warm Period was warmer
Does the D’Andrea et al. 2011 research say anything about what the authors believe their findings indicate about the general temperature of the arctic region during the medieval warm period? These are excerpts from the abstract for D’Andrea et al. 2012 published in GSA that indicate at the locations investigated were not as warm in the MWP as recent (not average for last 100 yrs.) temperature.
“The Svalbard Archipelago occupies an important location for studying patterns and causes of Arctic climate variability.”
“We find that the summer warmth of the past 50 yr. recorded in both the instrumental and alkenone records was unmatched in West Spitsbergen in the course of the past 1800 yr., including during the Medieval Climate Anomaly, and that summers during the Little Ice Age (LIA) of the 18th and 19th centuries on Svalbard were not particularly cold, even though glaciers occupied their maximum Holocene extent.”
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What's causing global warming? Look for the fingerprints
LandyJim, can you point to a model of real-world phenomena in any area of science that is not subject to your criticisms. All models of real-world phenomena fail at accuracy. Some models are useful; some are not. You can toss all the climate models out the window and still have excellent confidence that the climate system will store more energy with an increase in atmospheric greenhouse gas concentration. In fact, you can have high confidence that a doubling of atmospheric CO2 will result in about +1C equilibrium increase at the surface, without adding in any feedbacks. No GCMs necessary.
I don't know what you mean by "human intervention." Do you mean the different likely emissions scenarios? Models definitely incorporate those.
What SkS study?
What do you mean by the "chemistry of humanity" and the "chemistry of nature"? What do you think of when you think of each of those?
Moderator Response:[JH] Let's move this discussion to a more appropriate thread, i.e., How reliable are climate models? Thank you.
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kmalpede at 04:45 AM on 18 September 2013The 5 stages of climate denial are on display ahead of the IPCC report
American climate denier Prof.Richard Lindzen occupies the Alfred P. Sloan chair at MIT. Sloan Foundation funds plays about science, but refused to fund "Extreme Whether" because it is a play that unmasks the nefarious tactics of climate deniers. We need a culture of climate change...and one is growing, novels, photographs, plays, despite the difficulties with funding, the artists, like the scientists, will not be stopped.
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spoonieduck at 04:26 AM on 18 September 2013Medieval Warm Period was warmer
D'Andrea et al, using the 'alkenone thermometer' as applied to lake core sediments reported in Geophysical Research, vol. 13, 2011: "We generated a 5,000 year long, decadally resolved record of summer water temperature from the annually-laminated sediments of Lower Murray Lake on Ellesmere Island in the Canadian high Arctic.........Most notably, the alkenone record reveals warm lake water temperatures beginning approximately 800 A.D. and persisting until approximately 1200 A.D., with temperatures up to 2-3 deg C warmer than the mean temperature for the last 100 years. This distinct warm period of Ellesmere Island interrupted a Neoglacial cooling trend that began approximately 2,000 years earlier."
Using similar alkenone studies, D'Andrea and colleagues studied cores from the bottoms of Lake Braya So and E, close to the original Norse Greenland settlements. In 2011 they reported that, during the time of earliest Vikng coloniation, the weather was relatively mild, similar to today. Around 1100 A.D. the temperatures dropped 4 deg C in 80 years..... D'Andrea et al. reported these findings to the National Academy of Sciences.
Peter Steen Henrickssen, an archaeobotonist doing research--digging into middens left by the Greenland Norse--for the National Museum of Copenhagen claims to have found a few grains of charred barley in the lowest level of one of the middens. Because of the context and the presence of extraneous chaff, he believes that this was barley cultivated in the early days of the Greenland colonies. Today, no cereal grains can be grown in Greenland.
As you correctly noted, a few potatos are grown in southern Greenland today. Potatos weren't grown in Norse Greenland because potatos were only grown in the Andean mountains at the time. They weren't 'discovered' and brought to Europe until after 1528.
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LandyJim at 03:25 AM on 18 September 2013What's causing global warming? Look for the fingerprints
Not wishing to get into a debate of the merits of climate change as a whole, but i do see a flaw in the modelling used. Firstly, to do a model without human intervention requires a set of assumptions to be made that may or may not be accurate, secondly the Human only model requires a lot of assumptions to be made that may or may be accurate, and then they use the output to produce a model into which they add natural variations..
That is flawed science in my humble opinion, regardless of the truth about human impacts on the climate. People can pat themselves on the back all they like, but I am skeptical about the accuracy of such models.
We can argue about the impact of human activity on warming the climate all we like, but it is a proven fact that some human activity actually causes a cooling of the climate, was this taken into account in the models in the SKS study? I'll take a bet that it may have been overlooked or simply ignored as an "inconvenient truth" and the problem with that is that all your models are then inaccurate.
Lastly, has anyone completed a study to see how the chemistry of humanity and the chemistry of nature interact and impact the cliamte, the assumptions made about natural variations may be wrong because the chemistry if the atmosphere may be vastly different (good or bad) without humans dumping millions of tonnes of gases into the atmosphere each year.
Moderator Response:[JH] Let's move this discussion to a more appropriate thread, i.e., How reliable are climate models?
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CBDunkerson at 03:16 AM on 18 September 2013What's causing global warming? Look for the fingerprints
KR, I agree... except that their 'fans' are clearly too delusional to understand how stupid that ACM graph is.
Heck, the graph even winds up showing a small warming trend. Thus, the only 'knock' against SkS in the entire piece is in denouncing our "OMG we're all going to DIE" alarmism... and that's just a rather pathetic lie given the lack of any page like that on this site.
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Icarus at 03:03 AM on 18 September 2013The Pacific Ocean fills in another piece of the global warming puzzle, and puzzles Curry
Thanks K.a.r.S.t.e.N. I haven't gone into it in as much depth as you have, and yes I used the GISS forcing data. I think you're saying that the GISS aerosol forcing is too large, which would make the net forcing unrealistically small, and the sensitivity therefore too high... is that correct? I think James Hansen did an analysis relating to this in a recent paper - trying different response times and different aerosol forcings. Possibly this was the paper which brought on his comments about a 'Faustian bargain'. I will have to dig it out and re-read it...
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What's causing global warming? Look for the fingerprints
hank_ - Indeed, that's hilarious. They posted something attempting to diss the SkS Escalator emphasizing year-to-year variations (strawman, nobody seriously discusses trends from yearly varations) and portray a 12 year time-span for their "rational observers" (which is a prime example of the 'too short for significance' timespans shown in the SkS Escalator, uncertainties of about ±0.168 °C/decade 2σ).
Quite frankly an "own goal" for ACM, it makes them look quite the fools.
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hank_ at 01:50 AM on 18 September 2013What's causing global warming? Look for the fingerprints
Just a heads-up for all SkS readers. The Skeptical Science 'escalator' gets a mention on this Aussi blog. Well worth a look for a few laughs;
australianclimatemadness.com/2013/09/16/the-skeptical-science-escalator-of-alarmism/
Click the graph.
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