# Climatologist Dr. Michael Mann completely vindicated...again. **URL:** \ **Category:** Great Debates\ **Created:** [August 23, 2011, 12:17am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724 "2011-08-23T00:17:11Z")\ **Posts on this page:** 13\ **Page:** 24
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 10, 2011, 7:29am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/461 "2011-10-10T07:29:21Z")
> [@matt](#): > > Your cite does not remotely support your point and is only tangentally related to the subject, nor is anyone here claiming that the AMO causes global warming anyway. I have said (repeatedly?) in this very thread that it is an oscillation - it averages out to zero in the long term but causes bumps and dips in the trend. You did said to brazil84 “Not quite! Look, I’m no warmist. I accept that it’s entirely possible for Nature to produce a temperature upswing of the kind we’ve seen ALL ON HER OWN.” And one of the natural bits mentioned by you early was the AMO, I’m just saying that an answer like that has a lot of baggage (like the term warmist) and it is very clear where it comes from, but once again, I do see you on a better light as an skeptic, deniers like brazil84 are not doing good even with skeptics like you. It is just that one has to say that you are catching discredited labels to apply on others and there is also an unnecessary increase on the doubts when it is even doubtful that the deniers have a point by talking about the AMO. I mean, just by looking elsewhere on the IPCC and RealClimate it is clear that scientists already looked at it and they are highlighting the fact that most of the recent warming is global in scale and the AMO? Not driving things so much, like Tamino reported. > [@matt](#): > > Italics mine. Show me where I said that, or go to those sites and argue with them about it. I have explicitly said otherwise and I have only cited the IPCC in regards to the AMO - not any of the sites you are so down on. Do me the courtesy of not leaping to conclusions about my sources and then suggesting that I am “still catching some of the crap”. If you disagree with any points I make, _bring a technical argument_ to counter them. (Hint: spurious guesses as to where I’m getting my information from, and then dismissing it based on the assumed source, is not any kind of argument, technical or otherwise.) Never said that you did, I’m only using logic, as you already mentioned, you do look at sources like WUWT, the IPCC in reality is mentioning the AMO to point at the fact that they did take a look and reported that currently the AMO is not the main driver of the recent warming, when you reply to braiz84 to his comment that “For example, what caused the Little Ice Age? Nobody knows. So it’s reasonably likely that there are important forcings and interactions which are simply unknown.” With: > [@matt](#): > > _I absolutely accept this_, and I’d put it as more than “likely”. The AMO for example was only discovered in 1994 according to wiki, and the flat ARGO ocean energy content has provoked various “explanations” such as strong localised downwellings of warm water, or massive sulphate increases from Chinese coal-burning. There are many holes in our understanding." I have to see where do you get that “understanding” as mentioned even by you now if “it averages out to zero in the long term” then this business of implying that we can throw the AMO in with the unknowns is not the complete picture, so I’m just saying. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [October 10, 2011, 3:28pm UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/462 "2011-10-10T15:28:29Z")
> [@GIGObuster](#): > > You did said to brazil84 “Not quite! Look, I’m no warmist. I accept that it’s entirely possible for Nature to produce a temperature upswing of the kind we’ve seen ALL ON HER OWN.” Yes, and I stand by that. I don’t think it’s possible to prove that the current warming is unprecedented, nor do I think it’s important either way. As I said in page one of this very thread, in fact. > [@GIGObuster](#): > > And one of the natural bits mentioned by you early was the AMO, I’m just saying that an answer like that has a lot of baggage (like the term warmist) and it is very clear where it comes from, but once again, I do see you on a better light as an skeptic, deniers like brazil84 are not doing good even with skeptics like you. Yes, I mentioned the AMO earlier. E.g. in post 242, where I linked to the IPCC4 page on it and said _ **“Note that those IPCC graphs are NOT showing global warming - they are showing a long-period oscillation in Atlantic temperatures that is on top of global warming. The North Alantic shows an additional upward swing of about 0.7 deg. over the period 1970 - 2007 - about 0.19 deg. per decade over that time that is purely an energy oscillation and not a warming trend at all!”** _ I doubly emphasised that the AMO is a cycle and not a trend, even back then. > [@GIGObuster](#): > > It is just that one has to say that you are catching discredited labels to apply on others I mentioned my dislike of the polarisation of this matter into “sides” very early in this thread, and my first use of the phrase “warmist” was in quotes in post 406, in response to a question which incorporated the term. I’m not a big fan of “denier” either, which you seem more than happy to use freely. As I said, I’m in a dialogue and I sometimes answer questions in the same terms that they are framed in. > [@GIGObuster](#): > > and there is also an unnecessary increase on the doubts when it is even doubtful that the deniers have a point by talking about the AMO. I mean, just by looking elsewhere on the IPCC and RealClimate it is clear that scientists already looked at it and they are highlighting the fact that most of the recent warming is global in scale and the AMO? Not driving things so much, like Tamino reported. Tamino didn’t report anything, he performed a circular “analysis” that basically subtracted the AMO from itself. The AMO doesn’t drive anything - it produces cyclic bumps and dips on the Atlantic temperature record, and since the Atlantic is a fair chunk of global area those bumps and dips feed through into the global temperature record. Tamino may not like AMO, possibly because subtracting it from the temperature record makes the late 20th Century warming less severe, but if we lose the AMO then we also lose an explanatory factor for the early 20th century warming, as indicated by my realclimate cite. Your realclimate cite is basically a gripe about NOAA not attributing increased hurricane activity to AGW, and emphasises that the Atlantic sees both AGW plus the AMO - it’s not an either-or. It doesn’t support Tamino’s position that the AMO is an artefact. > [@GIGObuster](#): > > Never said that you did, I’m only using logic, as you already mentioned, you do look at sources like WUWT, the IPCC in reality is mentioning the AMO to point at the fact that they did take a look and reported that currently the AMO is not the main driver of the recent warming, when you reply to braiz84 to his comment that > > “For example, what caused the Little Ice Age? Nobody knows. So it’s reasonably likely that there are important forcings and interactions which are simply unknown.” > > With: “I absolutely accept this, and I’d put it as more than “likely”. The AMO for example was only discovered in 1994 according to wiki, and the flat ARGO ocean energy content has provoked various “explanations” such as strong localised downwellings of warm water, or massive sulphate increases from Chinese coal-burning. There are many holes in our understanding.” > > I have to see where do you get that “understanding” as mentioned even by you now if “it averages out to zero in the long term” then this business of implying that we can throw the AMO in with the unknowns is not the complete picture, so I’m just saying. I’m not saying the AMO is an unknown at all. I’m saying _it was an unknown before 1994_ which is comparatively recent, and it is entirely possible that we will discover other things we didn’t know about before we’re really on top of what’s happening. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 10, 2011, 4:10pm UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/463 "2011-10-10T16:10:25Z")
> [@matt](#): > > Yes, and I stand by that. I don’t think it’s possible to prove that the current warming is unprecedented, nor do I think it’s important either way. As I said in page one of this very thread, in fact. That does throw away the evidence gathered to calculate how sensitive climate is to changes, and the National academy of sciences reported on Mann’s work that: [http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=6222006](http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=6222006) > [@](#): > > Our confidence in the results of these reconstructions becomes stronger when multiple independent lines of evidence point to the same general result, as in the case of the Little Ice Age cooling and the 20th century warming. > > The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on icecaps and the retreat of glaciers around the world, which in many cases appear to be unprecedented during at least the last 2,000 years. > [@matt](#): > > I’m not saying the AMO is an unknown at all. I’m saying _it was an unknown before 1994_ which is comparatively recent, and it is entirely possible that we will discover other things we didn’t know about before we’re really on top of what’s happening. I’m just saying that we needed to clarify this, and you did, these clarifications are very important as long as you want to play fair to deniers (and even scientific organizations do call them that way) There is a big difference from an skeptic that does not ignore science like you from a denier that discusses for several posts that he is worried about the water vapor feedback, ignores the latest evidence on the water vapor, and then goes back to even denying that there is any valid evidence for the non feedback CO2 warming physicists expect. And then one has to still clarify further, even 2 degrees of increase is not without problems, as the IPCC is reporting that we will very likely get by a doubling of the CO2 in the atmosphere. As uncertainty goes both ways, it is not responsible to not tell others that the high end of the predictions from the IPCC are higher than that. “Best estimate for a “high scenario”[13] is 4.0 °C with a likely range of 2.4 to 6.4 °C (7.2 °F with a likely range of 4.3 to 11.5 °F)” ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [October 11, 2011, 12:57am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/464 "2011-10-11T00:57:32Z")
> [@GIGObuster](#): > > the National academy of sciences reported on Mann’s work that Your selective quote says what Mann’s 1998 and 1999 reconstructions implied, NOT what the National Academy of Science says about those reconstructions! From your very own cite: \*\*"3. It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies. 1. Less confidence can be placed in large-scale surface temperature reconstructions for the period A.D. 900 to 1600. Presently available proxy evidence indicates that temperatures at many, but not all, individual locations were higher during the past 25 years than during any period of comparable length since A.D. 900. The uncertainties increase substantially backward in time through this period and are not yet fully quantified. 2. Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about A.D. 900."\*\* Additionally, I posted links to Mann’s 2008 work in the first page of this thread, showing that much of the historic variation invisible in his 1998-1999 work is now back in his latest proxy reconstruction. I also showed where, by eliminating some of his proxies in his supplementary work, Mann himself produced a reconstruction where the MWP exceeds current temperatures. Since the proxy reconstructions tell different stories depending on what what proxies you pick, I have lost confidence in them being able to tell us much. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 11, 2011, 1:47am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/465 "2011-10-11T01:47:19Z")
> [@matt](#): > > Your selective quote says what Mann’s 1998 and 1999 reconstructions implied, NOT what the National Academy of Science says about those reconstructions! From your very own cite: > > \*\*"3. It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies. > > 1. Less confidence can be placed in large-scale surface temperature reconstructions for the period A.D. 900 to 1600. Presently available proxy evidence indicates that temperatures at many, but not all, individual locations were higher during the past 25 years than during any period of comparable length since A.D. 900. The uncertainties increase substantially backward in time through this period and are not yet fully quantified. > > 2. Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about A.D. 900."\*\* > > Additionally, I posted links to Mann’s 2008 work in the first page of this thread, showing that much of the historic variation invisible in his 1998-1999 work is now back in his latest proxy reconstruction. I also showed where, by eliminating some of his proxies in his supplementary work, Mann himself produced a reconstruction where the MWP exceeds current temperatures. Since the proxy reconstructions tell different stories depending on what what proxies you pick, I have lost confidence in them being able to tell us much. I’m sorry but on what you are basing that it is not the academy who is \*\*not \*\*telling us that: > [@](#): > > **Our confidence in the results of these reconstructions becomes stronger when multiple independent lines of evidence point to the same general result, as in the case of the Little Ice Age cooling and the 20th century warming.** > > The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. **This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators, such as melting on icecaps and the retreat of glaciers around the world, which in many cases appear to be unprecedented during at least the last 2,000 years.** BTW, less confidence does not mean that Mann was wrong, that “less confidence” item referred to some areas of the reconstruction, **and this also does not mean that then one should have no confidence at all**. The conclusion that was posted early comes after your quote, so lets not change the order of when the Academy is telling us that we should not trust any of those researchers. Still, what it needs to be said here is that it goes both ways, and that was the original beef I had with guys like brazil84, increasing the lack of confidence \*\*also \*\*means that there should be less confidence on the medieval warm period, really, the more one wants to dispose or discredit the paleoclimate evidence the more then one should doubt items like the medieval warm period, it \*\*should \*\*be dismissed then. I still have to see a denier (or should I have to include an skeptic like you on this item?) that has not ever stopped to notice the contradiction and reflect on the nonsense they are pushing. As long as skeptics do insist on bringing the medieval warm period as a way to seed doubts on the reasons for the current warming, they do so by also relying on the same paleoclimate data sources that scientists are using to tell us that the current warming is unprecedented for the precious 900 years and likely to be unprecedented for the previous 2000 years. > **[What evidence is there for the hockey stick?](https://skepticalscience.com/broken-hockey-stick.htm)** > > \Since the hockey stick paper in 1998, there have been a number of proxy studies analysing a variety of different sources including corals, stalagmites, tree rings, boreholes and ice cores. They all confirm the original hockey stick conclusion: the... > [@](#): > > Of course, these examples only go back around 500 years - this doesn’t even cover the Medieval Warm Period. When you combine all the various proxies, including ice cores, coral, lake sediments, glaciers, boreholes & stalagmites, it’s possible to reconstruct Northern Hemisphere temperatures without tree-ring proxies going back 1,300 years (Mann 2008). The result is that temperatures in recent decades exceed the maximum proxy estimate (including uncertainty range) for the past 1,300 years. When you include tree-ring data, the same result holds for the past 1,700 years. > Figure 6: Composite Northern Hemisphere land and land plus ocean temperature reconstructions and estimated 95% confidence intervals. Shown for comparison are published Northern Hemisphere reconstructions (Mann 2008). > > Paleoclimatology draws upon a range of proxies and methodologies to calculate past temperatures. This allows independent confirmation of the basic hockey stick result: that the past few decades are the hottest in the past 1,300 years. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [October 11, 2011, 3:00am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/466 "2011-10-11T03:00:44Z")
> [@GIGObuster](#): > > I’m sorry but on what you are basing that it is not the academy who is \*\*not \*\*telling us that: The academy is giving a mixed message. Highlighting the part you like and leaving the rest out changes the appearance of that message. > [@GIGObuster](#): > > BTW, less confidence does not mean that Mann was wrong, that “less confidence” item referred to some areas of the reconstruction, **and this also does not mean that then one should have no confidence at all**. Um, sure. So is it alright that I have less confidence in proxy evidence, especially the further back we go? > [@GIGObuster](#): > > The conclusion that was posted early comes after your quote, so lets not change the order of when the Academy is telling us that we should not trust any of those researchers. Where did I “change the order” of anything? Do you think the order determines which bits they really mean and which bits they don’t? How about numbered points - should they take priority? > [@GIGObuster](#): > > Still, what it needs to be said here is that it goes both ways, and that was the original beef I had with guys like brazil84, increasing the lack of confidence \*\*also \*\*means that there should be less confidence on the medieval warm period, really, the more one wants to dispose or discredit the paleoclimate evidence the more then one should doubt items like the medieval warm period, it \*\*should \*\*be dismissed then. I still have to see a denier (or should I have to include an skeptic like you on this item?) that has not ever stopped to notice the contradiction and reflect on the nonsense they are pushing. Good grief. In my previous post I said “Since the proxy reconstructions tell different stories depending on what what proxies you pick, I have lost confidence in them being able to tell us much.” That’s what I wrote. That’s what you _quoted._ What does that tell you about what I think of proxy reconstructions? > [@GIGObuster](#): > > As long as skeptics do insist on bringing the medieval warm period as a way to seed doubts on the reasons for the current warming, they do so by also relying on the same paleoclimate data sources that scientists are using to tell us that the current warming is unprecedented for the precious 900 years and likely to be unprecedented for the previous 2000 years. > > [What evidence is there for the hockey stick?](http://www.skepticalscience.com/broken-hockey-stick.htm) The 2000 year figure refers to local proxy indicators rather than global temperature reconstructions, but as for the rest of it: see above. I don’t think proxies can tell us much and I think trying to prove current warming is unprecedented, _or otherwise_ is pointless. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 11, 2011, 3:38am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/467 "2011-10-11T03:38:38Z")
> [@matt](#): > > The academy is giving a mixed message. Highlighting the part you like and leaving the rest out changes the appearance of that message. And that is why Mann came back in 2008 taking into account the academy’s recommendations, the point here is that this is not pointless. 🙂 The Academy in the end did not claim Mann was wrong on everything, however the main idea remained and still remains a serious area of research. And the 2008 reconstruction is not restricted to local proxies, but it is global: [http://www.ncdc.noaa.gov/paleo/pubs/pcn/mann2008fig1.jpg](http://www.ncdc.noaa.gov/paleo/pubs/pcn/mann2008fig1.jpg) > **[Paleoclimatology | National Centers for Environmental Information (NCEI)](https://www.ncei.noaa.gov/products/paleoclimatology)** > > NCEI manages the world's largest archive of climate and paleoclimatology data. Our mission is to preserve and make this data and information available in order to understand and model environmental variability on an interannual to millennial time... “Paleo provides data and information scientists need to understand natural climate variability and future climate change.” ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [October 11, 2011, 5:02am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/468 "2011-10-11T05:02:29Z")
> [@GIGObuster](#): > > And that is why Mann came back in 2008 taking into account the academy’s recommendations, the point here is that this is not pointless. 🙂 > > The Academy in the end did not claim Mann was wrong on everything, however the main idea remained and still remains a serious area of research. I gave Mann credit for the pioneering nature of his work on the first page of this thread. That said, I’m convinced that the proxy data can only give the general shape of the historic temperature trends at best and is probably fairly distorted. It’s Mann’s work that convinced me of this, as I explain below. > [@GIGObuster](#): > > And the 2008 reconstruction is not restricted to local proxies, but it is global: > [http://www.ncdc.noaa.gov/paleo/pubs/pcn/mann2008fig1.jpg](http://www.ncdc.noaa.gov/paleo/pubs/pcn/mann2008fig1.jpg) I think all the reconstructions by Mann and others have been global to some degree. That incidentally isn’t a map of the proxies Mann used - its a map of the proxies in the database from which Mann selected. It’s shown in Mann’s 2008 paper which I linked to in post 14: [http://holocene.meteo.psu.edu/shared/articles/MannetalPNAS08.pdf](http://holocene.meteo.psu.edu/shared/articles/MannetalPNAS08.pdf). The map of proxies Mann actually _used_ is in figure S1B of the supporting information: [http://www.pnas.org/content/suppl/2008/09/02/0805721105.DCSupplemental/0805721105SI.pdf#nameddest=STXT](http://www.pnas.org/content/suppl/2008/09/02/0805721105.DCSupplemental/0805721105SI.pdf#nameddest=STXT) The supporting information also lists the proxies used: 105 dendro (tree ring) proxies, 81 non-dendro reconstructions including the 4 Tiljander sediment series, 19 historical temperature records and 71 “composite” reconstructions. It shows in figure S7 what happens if you take out the 105 dendro proxies - not too much. And then in figure S8 what happens if you take out the seven possibly problematic non-dendro series mentioned in the text (the four Tiljander plus three others known to be contaminated after 1870, 1870 and 1940 respectively) and there is very little difference - not surprising since it is only 7 series out of 270-odd. But later he released what happens if you take out the dendro and the 7 together (the cyan line here: [http://www.meteo.psu.edu/~mann/supplements/MultiproxyMeans07/NHcps\_no7\_v\_orig\_Nov2009.pdf](http://www.meteo.psu.edu/~mann/supplements/MultiproxyMeans07/NHcps_no7_v_orig_Nov2009.pdf)) and it makes a big difference - the variance has increased dramatically and the MWP spikes up to around current temperatures. Do I believe the MWP was warmer than today? I don’t know and don’t think we _can_ know. Mann’s data using 160-odd non-dendro records says yes, and changes to no again if you add in seven “problematic” records. Or another way to look at it is, if you remove the “problematic” seven then the dendro and non-dendro don’t match anymore. What are we to make of that? ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 11, 2011, 5:24am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/469 "2011-10-11T05:24:29Z")
> [@matt](#): > > I gave Mann credit for the pioneering nature of his work on the first page of this thread. That said, I’m convinced that the proxy data can only give the general shape of the historic temperature trends at best and is probably fairly distorted. It’s Mann’s work that convinced me of this, as I explain below. > I think all the reconstructions by Mann and others have been global to some degree. That incidentally isn’t a map of the proxies Mann used - its a map of the proxies in the database from which Mann selected. It’s shown in Mann’s 2008 paper which I linked to in post 14: [http://holocene.meteo.psu.edu/shared/articles/MannetalPNAS08.pdf](http://holocene.meteo.psu.edu/shared/articles/MannetalPNAS08.pdf). The map of proxies Mann actually _used_ is in figure S1B of the supporting information: [http://www.pnas.org/content/suppl/2008/09/02/0805721105.DCSupplemental/0805721105SI.pdf#nameddest=STXT](http://www.pnas.org/content/suppl/2008/09/02/0805721105.DCSupplemental/0805721105SI.pdf#nameddest=STXT) > > The supporting information also lists the proxies used: 105 dendro (tree ring) proxies, 81 non-dendro reconstructions including the 4 Tiljander sediment series, 19 historical temperature records and 71 “composite” reconstructions. It shows in figure S7 what happens if you take out the 105 dendro proxies - not too much. And then in figure S8 what happens if you take out the seven possibly problematic non-dendro series mentioned in the text (the four Tiljander plus three others known to be contaminated after 1870, 1870 and 1940 respectively) and there is very little difference - not surprising since it is only 7 series out of 270-odd. But later he released what happens if you take out the dendro and the 7 together (the cyan line here: [http://www.meteo.psu.edu/~mann/supplements/MultiproxyMeans07/NHcps\_no7\_v\_orig\_Nov2009.pdf](http://www.meteo.psu.edu/~mann/supplements/MultiproxyMeans07/NHcps_no7_v_orig_Nov2009.pdf)) and it makes a big difference - the variance has increased dramatically and the MWP spikes up to around current temperatures. Do I believe the MWP was warmer than today? I don’t know and don’t think we _can_ know. Mann’s data using 160-odd non-dendro records says yes, and changes to no again if you add in seven “problematic” records. Or another way to look at it is, if you remove the “problematic” seven then the dendro and non-dendro don’t match anymore. What are we to make of that? I would go for what NASA accepts, they have not gotten rid of Mann nor his conclusions, the point here is that > **[Paleoclimatology | National Centers for Environmental Information (NCEI)](https://www.ncei.noaa.gov/products/paleoclimatology)** > > NCEI manages the world's largest archive of climate and paleoclimatology data. Our mission is to preserve and make this data and information available in order to understand and model environmental variability on an interannual to millennial time... > [@](#): > > In particular, reconstructed temperatures from proxy data for the past 1000 years have allowed an assessment of the warming over recent decades and indicate that at least part of this warming is due to the impact of human activities on climate, according to the Intergovernmental Panel on Climate Change (IPCC). > > Geological evidence demonstrates that the Earth’s climate is dynamic, and has varied widely from our everyday experience. Over the past two million years, numerous glacial periods have covered much of the northern hemisphere in glacial ice, dropped sea level as much as 125 meters, and significantly cooled even tropical regions. In the more distant past, the Cretaceous Period was significantly warmer than today, with less polar ice, raising sea levels and allowing warm weather organisms to thrive even in near-polar regions. In the past 150 years, instrumental weather records indicate that the Earth has warmed by approximately 0.6°C. Our goal is to provide an archive of past climate observations, derived from multiple proxies, that enables scientists to understand and model the many different states of the climate system that have existed in the past. The point here is that if you are more correct than Mann and others, then it should be easy on this current political environment to denounce outfits like NASA for following bad science, but somehow, I do not think that NASA nor the National Academy of Sciences would agree with the idea that they just posted a mixed message or told Mann that he is still wrong, if that was the case then it should be easy to find cites from the Academy complaining to Mann for continuing to misinterpret them or they reporting that Mann is continuing to doing it wrong. > **[Paleoclimatology | National Centers for Environmental Information (NCEI)](https://www.ncei.noaa.gov/products/paleoclimatology)** > > NCEI manages the world's largest archive of climate and paleoclimatology data. Our mission is to preserve and make this data and information available in order to understand and model environmental variability on an interannual to millennial time... > **[404 Page Not Found](https://www.vaildaily.com/404-page-not-found)** > > The page you were looking for could not be found.You might be able to find the page by entering a few keywords in the search box above. > [@](#): > > The highest scientific body in the nation, the National Academy of Sciences affirmed my research findings in an exhaustive independent review published in June 2006 (see e.g. “Science Panel Backs Study on Warming Climate,” New York Times, June 22, 2006, among many others). > > Dozens of independent groups of scientists have independently reproduced and confirmed our findings, and more recent work by several groups shows that recent warmth is unusual over an even longer time frame. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [October 11, 2011, 8:06am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/470 "2011-10-11T08:06:53Z")
Your world is _incredibly_ black and white, is all I can say. You really think academia is so polarised that there’s no variety of opinion within it? That being unconvinced by the paleo approach is the same as thinking Mann’s science is bad? That NASA is a monolithic body which makes endorsing or rejecting research its business? Since I’ve basically been reiterating stuff I said in the beginning of the thread for the last few posts, I think we’ve started to go in circles so I’m done for now. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 11, 2011, 4:56pm UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/471 "2011-10-11T16:56:53Z")
> [@matt](#): > > Your world is _incredibly_ black and white, is all I can say. You really think academia is so polarised that there’s no variety of opinion within it? That being unconvinced by the paleo approach is the same as thinking Mann’s science is bad? That NASA is a monolithic body which makes endorsing or rejecting research its business? Once again, being unconvinced implies that somewhere that research is wrong, The point here is that it should not be too hard to get the best skeptical minds on the subject to let NASA and others on the reasons why Mann is unconvincing, somehow 🙂 I do think that groups like NASA also asked around before accepting Mann’s research. You see, I originally approached this issue from an historical perspective, there is this little item called the march of science in it. Currently the best available science is telling us something that many people do not like. As Feynman could say, it does not matter how great or neat the idea that this is pointless or mixed so much is, if the evidence says otherwise this idea that it is pointless is wrong. The fact is that climate centers are using Mann’s research, his research would by now be dismissed if it had not been confirmed by others. \*\* I appreciate what you are doing against deniers here, but one can not ignore the “squik” ideas like the “pointless” one are still coming out.\*\* The latest squik item is 100% related to the OP and the research that Mann is involved with. But we have to go back in time a little: The first reconstruction of past climate came with a huge medieval warm period, it was that early reconstruction published by the IPCC the one that was grabbed by skeptics to tell others that everything was alright, the warming of today can be explained as being entirely natural as like in the past. [![](https://img.youtube.com/vi/vrKfz8NjEzU/hqdefault.jpg "Climate Denial Crock of the Week - "The Medieval Warming Crock"") ](https://www.youtube.com/watch?v=vrKfz8NjEzU) Going to the present (as an aside, I have noticed before how peculiar are conservatives that politicize this issue, they also have trouble dealing with the march of time) There are 3 problems by ignoring the current research and sticking with the early reconstruction. One problem is that it needs to deny that new data could be gathered and new reconstructions made, then it has to deny that new data does change the graph that one should get as a result. And then it has to deny that there is now better evidence that enables scientists to understand and better model the many different states of the climate system that have existed in the past. Skeptics had more support back in the recent past to remain skeptics, data and sources not being readily available, tree rings having an already pointed out problem in the recent decades, etc. But those issues were deal with in the latest research and one has to notice that the latest 2008 research by Mann is still being criticized by using the mild criticism made by the National Academy of his research from 1998-2001. What you are calling “black and and white” I just call it the result of the progress scientists have achieved so far, when I look at history (and the very recent one) what I see is a progression from the climate change denial side to become like creationists when they tell others that there is a huge controversy on virtually all aspects of evolution, but just like [talkorigins.org](http://talkorigins.org) pointed out, it is in academia and the research world where these pontifications of “lack of confidence” on an issue are being constantly verified by the experts on the field. As talkorigins put it recently: “sure you want to teach the controversy, so where is it?” It had been years since people like Behe had published his “definitive” book against evolution and a look at the academic sources showed how pathetic his footprint or influence in academia was really after 10 years, but this is not an exercise on popularity, research would by now had supported many of his ideas against evolution, but the only thing we got was even more evidence that evolution was and is real. Of course, I do not see that disregard of evidence from skeptics like you **matt** , however there are still very peculiar items on your skepticism and if the evidence and history does not match an important item you are referring to then it is important to clarify where we are. After a process of decades, researchers like Mann are getting better data and getting more confidence on the ranges that then other climate researches use. The research of Mann is only one piece of the whole effort to understand the current global warming and the most likely effects humanity will encounter if nothing is done. ---
**Author:** ![brazil84](https://avatars.discourse-cdn.com/v4/letter/b/8491ac/32.png) [@brazil84](https://boards.straightdope.com/u/brazil84)\ **Post date:** [October 13, 2011, 2:04am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/472 "2011-10-13T02:04:49Z")
> [@matt](#): > > . > > Well the second question was: _“Well then lets go back to your analogy: Let’s suppose someone predicts that with new air filters your car’s gas mileage will increase by 10%. There are also numerous other factors which may affect mileage; and mileage is also constantly changing. If the car’s gas mileage is observed to increase by 6% over the next 40 miles, is it reasonable to attribute essentially all of the change to the air filter?”_ There is insuficient information to answer that question. By what percentage has mileage been “constantly changing” in the past? What do we know about the “numerous other factors” and can we reasonably compensate for their effects over the 40 mile trial? (1) By at least roughly 10% up or down, and possibly more. All for reasons unknown. (2) We know very little about the other factors, but we do know that they can cause 10% changes in mileage. Can you answer the question now? > [@](#): > > I reject your analogies here. The fundamental predictions are not based on computer predictions - many of them were made before computers existed! The 3.7 watt/ sq. metre per doubling is a simple radiative transfer calc. The 1.1-1.2 deg. C per doubling is a simple black-body radiation calc based on the 3.7 watt figure. Those are clean calcs, no computers required. Those are not warmist predictions. As I have repeatedly pointed out, warmists predict that global surface temperatures will increase substantially more than what would be predicted by this type of simple calculation. Warmists predict that there are second order effects which will cause greater increases. You have admitted this yourself. > [@](#): > > The prediction of increasing specific humidity with temperature, and therefore _some_ water vapour amplification, is a physics-based no brainer. No it is not, because it also requires you to make assumptions about other second order effects. Besides, if it were simply a matter of physics, there wouldn’t be disagreement about sensitivity among warmists. > [@](#): > > Additionally there have been several attempts to evaluate the climate sensitivity empircally from the known forcing history and the temperature record, an approach I have more faith in. Schwartz’s 2007 paper was probably the first attempt published and gave a figure of 1.1 deg. C per doubling - basically the same as the black body response with no net additional feedbacks. Scarfetta pointed out some problems with Schwartz’s method and calculated his own value of 1.7. Schwartz accepted Scarfetta’s work and published again in 2008 with a figure 0f 1.9 and uncertainty +/- 1, in line with Scarfetta. I trust the empirical work rather more than the computer models, which is one reason why I think the sensitivity will turn out to be at the lower end of the IPCC range. I doubt there is enough empirical data to evaluate sensitivity in this way. It goes back to the problem of unknown forcings, which clearly exist. > [@](#): > > Well you appear to be dismissing some or all of an extra 3.7 watts/ sq. m, based on: _“In my view, the natural a priori assumption should be that the system will push back even if we do not know the exact mechanisms at work.”_ Well if you like, I will assume nothing, not even a modest warming in response to CO2 increases. Now the full burden is on you. > [@](#): > > I argue that the black-body response is a negative feedback that already “pushes back” and so there is no need to invoke any extra unknown negative feedback mechanisms. Well this is just semantics, but it’s reasonable in my opinion to characterize second order (and third order) responses as “feedback.” > [@](#): > > As I thought I’d already said, I don’t dismiss the possibility that there are unknowns that affect the picture - I think it’s virtually certain that there are. I won’t be particularly suprised if the warming we’ve seen turns out to be up to 50% natural. Well that means you are confident that whatever factor caused warming in the first half of the twentieth century substantially diminished in the second half. > [@](#): > > Observation, physics, modelling, paleohistory, all indicate that the system’s temperature response will be somewhat greater than the black body response. No they do not. Observation does not since there are unknown factors at work. “Physics” has the same problem as well as the problem of disagreement. “Modelling” does not either since none of the simulations have been tested and validated. Further, there is excellent reason to believe that the simulations are simply tuned to fit history. Last, I’m not sure what you mean by paleohistory, but it seems to me this has the same problem as observations, combined with the problem of actually estimating temperatures and other factors, which makes the picture only fuzzier. ---
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [October 13, 2011, 3:03am UTC](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724/473 "2011-10-13T03:03:45Z")
> [@brazil84](#): > > No they do not. Observation does not since there are unknown factors at work. “Physics” has the same problem as well as the problem of disagreement. “Modelling” does not either since none of the simulations have been tested and validated. Further, there is excellent reason to believe that the simulations are simply tuned to fit history. Last, I’m not sure what you mean by paleohistory, but it seems to me this has the same problem as observations, combined with the problem of actually estimating temperatures and other factors, which makes the picture only fuzzier. And like clockwork there is brazil84 still insisting after all these years that there is no testing or validation, this point is not correct at all. > **[Earth Science | Earth](https://earth.gsfc.nasa.gov/?section=10)** > [@](#): > > To date, GMI has developed tests that include temperature, barrier formation, and meridional transport in the stratosphere, including the UT/LS. Some of these tests have become part of the evaluations used in the Chemistry-Climate Model Validation Activity (CCMVal) for SPARC (Stratospheric Processes and their Role in Climate). More information on GMI transport and chemistry tests can be found in publications by Douglass et al. [1999], Strahan and Douglass [2004], Douglass et al. [2004], Strahan and Polansky [2006], and Strahan et al. [2007]. > > GMI will continue to work with groups involved in the study of chemistry-climate coupling by testing modules with observations in a CTM framework. As an example, GMI team members have used a wide range of existing observations to evaluate the GMI “Combo” chemistry, deposition and emission modules. Their successful evaluation has resulted in incorporation of these modules into the GEOS-5 GCM system as part of an ongoing chemistry-climate evaluation effort. As he will not pay attention to this, IIRC he likes to denigrate that testing by claiming that it is not Independent Verification and Validation (IV&V), contrarians like him are doing so by ignoring how inappropriate that kind of verifications is in this case. \* > **[Do Climate Models need Independent Verification and Validation? | Serendipity](http://www.easterbrook.ca/steve/2010/11/do-climate-models-need-independent-verification-and-validation/)** > > A common cry from climate contrarians is that climate models need better verification and validation (V&V), and in particular, that they need Independent V&V (aka IV&V). George Crews has been arguing this for a while, and now Judith Curry... > [@](#): > > As a measure of how well this process works for building scientifically valid models, one senior modeller recently pointed out to me that it’s increasingly the case now that when the models diverge from the observations, it’s often the observational data that turns out to be wrong. The observational data is itself error prone, and software models turn out to be an important weapon in identifying and eliminating such errors. > > However, there is another risk here that needs to be dealt with. Outside of the labs where the models are developed, there is a tendency for scientists who want to make use of the models to treat them as black box oracles. Proper use of the models depends on a detailed understanding of their strengths and weaknesses, and the ways in which uncertainties are handled. If we have some funding available to improve the quality of climate models, it would be far better spent on improving the user interfaces, and better training of the broader community of model users. > > The bottom line is that climate models are subjected to very intensive system testing, and the incremental development process incorporates a sophisticated regression test process that’s superior to most industrial software practices. The biggest threat to validity of climate models is errors in the scientific theories on which they are based, but such errors are best investigated through the scientific process, rather than through an IV&V process. Which brings us to: > > (3) the assumption that our ability to trust in the models can be improved by an IV&V process; > > IV&V is essentially a risk management strategy for safety-critical software when which an iterative development strategy is not possible – where the software has to work correctly the first (and every) time it is used in an operational setting. Climate models aren’t like this at all. They aren’t safety critical, they can be used even while they are being developed (and hence are built by iterative refinement); and they solve complex, wicked problems, for which there’s no clear correctness criteria. In fact, as a species of software development process, I’ve come to the conclusion they are dramatically different from any of the commercial software development paradigms that have been described in the literature. > > A common mistake in the software engineering community is to think that software processes can be successfully transplanted from one organisation to another. Our comparative studies of different software organizations show that this is simply not true, even for organisations developing similar types of software. There are few, if any, documented cases of a software development organisation successfully adopting a process model developed elsewhere, without very substantial tailoring. What usually happens is that ideas from elsewhere are gradually infused and re-fashioned to work in the local context. And the evidence shows that every software oganisation evolves its own development processes that are highly dependent on local context, and on the constraints they operate under. Far more important than a prescribed process is the development of a shared understanding within the software team. The idea of taking a process model that was developed in the aerospace industry, and transplanting it wholesale into a vastly different kind of software development process (climate modeling) is quite simply ludicrous. - **Or maybe they do know what it leads to** and are pushing for it as yet another attempt at delaying research, this becomes obvious after reading more of the post from this computer expert. [Previous page](https://boards.straightdope.com/t/climatologist-dr-michael-mann-completely-vindicated-again/593724.md?page=23)