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View Diary: Paleoclimatology Primer 2 (29 comments)

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  •  For starters (0+ / 0-)

    don't question people's motivations, or their grasp of a subject.  It doesn't contribute in anyway other than to drive emotion into a discussion that is based on facts.  

    That being said, either in my haste I didn't type things clearly enough, or you misread what I wrote.  When I said

    My source was the IPCC which reports a projected temperature increase of 1.1 to 6.5°C over the next century.  I rounded from 1.1°C for ease of use.  While is is the lower range of the projections, and is likely to be low from reality, it is the only temperature increase we can be sure will happen.

    I didn't say anything about the probability of other values.  I am only saying, as the lower end we can guarantee that any thing that would happen at 1°C is going to happen.  If the correct number is 3°C, you still have to go through 1°C to get there.  If the answer is 100°C, you still have to go through 1°C to get there.  That is not the same as the upper end of the range.  So the only number that you can guarantee will happen is the low end of the range.  I wasn't saying anything about where the final temperature will end up in 2100.  Can we agree on that?

    You are also wrong about your probability distribution claim.  Your statement of the highest probability being at the middle of the peak is only correct if you have a random data set, which this range most certainly is not.  It consists of 6 different models, each with different inputs and sensitivities.  You cannot simply take the average of those model as the most probable answer because they do not start with the same inputs.  Think of the probability curve of this range as 6 different and overlapping curves, resulting in a very complex equation.

    I stand by the claim that there is a lot of hero worship of Hansen.  Yes, his numbers have been very good in the past.  But that doesn't mean you should throw out everyone else's models just because they give a different number than Hansen's model does.  If you really think that his record is so great, maybe everyone else should just quit the IPCC and we will let him write it.  He is a great scientist, but just because he has a great track record in the past doesn't mean that he will always be right.  You have to concede that point.  Otherwise, what is even the point of scientific inquiry?

    As for when you said this:

    They cite a 1988 study by Hansen that predicted a climate sensitivity of 4.2C. Indeed Hansen was off in his estimate back then, it turns out to be about... guess what... yep ... 3.0C.

    How do we know what the answer turned out to be?  It isn't 2100 yet.  3.0°C is simply what his latest model says.  No doubt Hansen will continue to refine his models in ways he hasn't even thought of.  And how do we know that his model 5 years from now won't say the answer is 2.4°C?  Or maybe 4.4°C?  We won't know until he designs his next model.  Unless you think he is retiring from science, I think we can trust he will always be making his models better and not simply stating that this one is 'good enough'.

    You said:

    There IS a narrowing consensus, right around 3C, multiple researchers, multiple methods say so.

    This statement is true and you will never see me argue it.  But the key word here is 'narrowing' and the fact that the range is centered on 3°C.  The range that the community is agreed upon is narrowing.  But there is no consensus on 3°C being the answer.  The consensus of the community is that, by 2100, the temperature will have increased by 1.1 to 6.5°C, with the average value being 3°C.  

    I love SkepticalScience, I send people to them all the time, but one website does not a consensus make, no matter how smart they are.  I am a paleoclimatologist, actively doing research and publishing in major journals.  I participate in these debates.  I was in San Francisco in December at the American Geophysical Union Meeting having these very discussions (though nobody there accused me of not knowing what I am talking about), and I can tell you from personal experience there is a range of values bandied about for 2100, but they are all in that range.  You are not going to convince me of a consensus using someone else's opinion when I have first hand experience in the matter.  Unless you want me linking to dozens of models that come up with numbers different from 3.0°C.

    I ask you to go back and look at the actual IPCC data before saying the lowest scenario is 1.8°C.  The lowest model result (B1) gives a range of 1.1 to 2.9°C with a median result of 1.8°C.  You stated that you can't throw out the whole range for one number.  This is the same case here.  

    The last bit you had in there, I don't see you disagreeing with anything I said.  In fact I see you making my point even further.  As far as I can see, I said exactly what the bolded text says.  The resulting change would be a disaster.  This is why we have to do something, because even the low end (1°C) results in the destruction of the coral reef ecosystem, the tropical rainforest system and 20-30% of all life on this planet.  I don't see your problem here.

    When I am talking about alarmists I am talking about the people who believe that all life on this planet will go extinct and we as a species will go extinct.  We are remarkable adaptable as a species, we will absolutely survive as a species even the worst case scenario, but it will be civilization changing.  By making the Armageddon claims you end up looking like the loon on the corner wearing a sandwich board that no one listens to.  Be honest and state that even small changes will destroy whole ecosystems.  Isn't that bad enough for you?

    I will state one last thing about your following quote:

    I could go on for pages picking holes in your diary and comments, but I think you get the main point.

    Bring it on, especially the diary.  There is nothing in there that is incorrect.  I will even email you pdf's of every one of those references if you want to pour through them.  I may make an error here or there in comments when I am rushing to type, but my diary is well researched.  You could submit it to a dissertation committee if you want.  You won't find any errors.

    I regret using the 1°C number.  I knew it was the low range of projections when I used it, but that is because I was trying to show how important it is to work these issues out.  If I had not been lazy and changed

    And before you ask, what is the point of arguing over a single degree, remember that the human caused climate change we are facing is projected to be approximately 1°C on average. One degree of temperature change for our planet as a whole is a very major deal.

    to

    And before you ask, what is the point of arguing over a single degree, remember that the low end of human caused climate change we are facing is projected to be approximately 1°C on average. One degree of temperature change for our planet as a whole is a very major deal.

    you wouldn't have had one thing to say about my diary.  Because that is the only thing you have criticized in my diary, the rest was all from just one comment that I had to write quickly because the other one was erased.  And I clearly didn't write it very well, because you misinterpreted half of the points I was making.

    All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. - Schopenhauer

    by BlueberryTomatoSoup on Wed Feb 16, 2011 at 10:08:34 PM PST

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    •  Ok... let me decompress this, at least little... (0+ / 0-)

      Having now read your previous diaries, and considered your comments, it's clear you're not trying to mislead anyone, and my knee-jerk first comment was perhaps a bit confrontational.

      "I regret using the 1°C number."

      Good enough.  Thank you sir, that wasn't so hard after all, was it?  To be honest, I was still in combat mode over your original stipulation ("...the human caused climate change we are facing is projected to be approximately 1°C on average") had your original diary had the nuance that you added in your first reply, that "it's the only temperature increase we can be certain of." I would likely have seen some sort of merit in that interpretation, as misleading as it might be.

      Going forward, I haven't really deeply considered your discussion of isotopic ratios in reconstructing paleoclimate.  I scan read it, just like I pretty much scanned the original papers on the Vostok Ice Cores when they came out (Yep, I'm THAT old) but I did read the abstracts and struggled through their conclusions.  Your explanation of the reconstruction method sounded just fine to me. To be honest it was a bit over my head, and probably over the heads of  most others here.  (I AM tempted to take you up on your offer of finding further errors in your diary, but that's not my field, and I really do have a life somewhere else.)

      Some other random stuff from you last comment:

      "I ask you to go back and look at the actual IPCC data before saying the lowest scenario is 1.8°C.  The lowest model result (B1) gives a range of 1.1 to 2.9°C with a median result of 1.8°C.  You stated that you can't throw out the whole range for one number.  This is the same case here."

      Dude, that is exactly what I asked you to do in my first comment.  Find me ANYTHING that says a 1C AGW is what we are facing, and to specify your time frame, because if you weren't talking about 2000 to 2100, you may well have been bang-on. As it is, you were wrong.   I said nothing about "throwing out a whole range of numbers" those are your words, which you seem to be happy to substitute for the words of others whenever you are faced with a vexing argument. (As you did with the "hobbyist" post at Skeptical Science.)

      What I did say was you can't take a number at the EXTREME LOW END OF THE ESTIMATE and imply that's the likely scenario, but since you've backed off of your original claim and now say it's a 'minimum expected' I might not argue with that, even if it's still low by 0.8C, in the most favorable scenario out of 6 representative IPCC scenarios.  And that median result for B1 of 1.8C? It's referred to as the BEST ESTIMATE, note that the best estimate is NOT the number at the low end of the range.

      To make my point in another context, if the best models available said that Green Bay was going to beat Pittsburgh by 3 points in the Super Bowl, with a range of 1 to 6 points, would you tell people that 1 point is most likely scenario?

      Have I beat this to death enough for you yet?   You seemed to have gotten it with  your "I regret..." statement above, then you slither back and try to justify it once again.

      "I stand by the claim that there is a lot of hero worship of Hansen.  Yes, his numbers have been very good in the past.  But that doesn't mean you should throw out everyone else's models just because they give a different number than Hansen's model does."

      Actually, what's popular in many circles is to attack Hansen.  I guess mostly because he's gone over to what seems like a crusade... unseemly for a scientist.  Personally I can't blame him, he didn't go looking for a political confrontation, he was doing science, the political confrontation came to him. And as you say, Hansen's work, and the work of the dozen-or-so other researcher/co-authors on his papers, is "beyond reproach." (Though at first blush that seems an odd stipulation for someone who thinks Hansen et al are wrong by at least 300 percent in their predictions.)

      "As far as I can see, I said exactly what the bolded text says."

      No.  The bolded text has a number of  qualifiers, it has "medium confidence" that the (unspecified) "plant and animal species assessed so far"  are  "likely to be at increased risk of extinction" and they're likely talking about sensitive species (that's my interpretation, though the language isn't explicit)  that is VASTLY different from your  "...very likely to lead to a mass extinction of 20-30% of all life on this planet."

      A scientist wouldn't make that and other sloppy mistakes that you have made.  This isn't a a peer reviewed journal, so dropping the endless qualifiers, and a bit of rounding, and using shorthand are perfectly acceptable. But Einstein advised "Make everything as simple as possible, but not simpler." And we still have an obligation to the facts.

      •  We are still miscommunicating (0+ / 0-)

        I will try one more time.  I do NOT believe that 1°C is the most likely scenario.  I personally believe the most likely number will be closer to 2.4°C with a range of ~1.5°C to 3.8°C, as projected by model B2.  That doesn't mean I think Hansen is wrong, on the contrary, his model results are within the range of the B2 results.  It is just from my analysis of the model inputs, I think B2 is going to best represent the way we will approach the problem (decrease our rate of fossil fuel usage increase, but not decrease our usage itself).  Below is a description of the different model inputs.  

        The A1 storyline assumes a world of very rapid economic growth, a global population that peaks in mid-century and rapid introduction of new and more efficient technologies. A1 is divided into three groups that describe alternative directions of technological change: fossil intensive (A1FI), non-fossil energy resources (A1T) and a balance across all sources (A1B). B1 describes a convergent world, with the same global population as A1, but with more rapid changes in economic structures toward a service and information economy. B2 describes a world with intermediate population and economic growth, emphasising local solutions to economic, social, and environmental sustainability. A2 describes a very heterogeneous world with high population growth, slow economic development and slow technological change. No likelihood has been attached to any of the SRES scenarios. {WGIII TS.1, SPM}

        This is why you can't just make a simple probability distribution out of the total range from the 6 scenarios.  When trying to figure out what the correct projection is, you need to decide which input most accurately reflects how the world will react to the coming crisis.  Then you look at the results from that model.  This isn't Stats 101, its more like Stats 240.

        I will reassess which model I think best represents our projected climate change when the AR5 report comes out.  That doesn't mean I think the other models are incorrect, in science it is possible to believe that one model is more likely than another while accepting that other models could be right.  We won't know the actual result until 2100.  I don't expect to make it that long, but we should have a reasonably good idea where we are going by ~2030.  

        The real point where we aren't communicating is you think I am trying to say that 1°C is the most likely scenario, when I am saying that the change will be at least 1°C.  To use your Superbowl analogy, I would not say that 1 point was the most likely result.  I would say that the Packers will win by at least 1 point.  This way you can't be wrong, whether they win by 1 or 6, you covered all of those options by saying they will win by at least 1.  That is all I am saying here.  The temperature change is going to be at least 1°C.  So we can guarantee that the changes associated with 1°C will happen.  That doesn't say anything about 2 or 3 or 6°C changes.  Those happen in addition to the changes that we know will happen because the globe will warm by at least 1°C.

        The whole point is you have to report the ranges of the projections.  If you only report the most likely result, it is not hard to end up wrong.  If you say the number is 3°C and the number is 2.8°C, you are wrong.  If you say the number is between 2.5 and 3.5°C centered around 3°C, and the answer is 2.8°C you were right.  That is how science works.

        As for the extinction thing, you are kidding right?  The IPCC had to define all of these terms,

        Where uncertainty is assessed more quantitatively using expert judgement of the correctness of underlying data, models or analyses, then the following scale of confidence levels is used to express the assessed chance of a finding being correct: very high confidence at least 9 out of 10; high confidence about 8 out of 10; medium confidence about 5 out of 10; low confidence about 2 out of 10; and very low confidence less than 1 out of 10. ...  Where uncertainty in specific outcomes is assessed using expert judgment and statistical analysis of a body of evidence (e.g. observations or model results), then the following likelihood ranges are used to express the assessed probability of occurrence: virtually certain >99%; extremely likely >95%; very likely >90%; likely >66%; more likely than not > 50%; about as likely as not 33% to 66%; unlikely <33%; very unlikely <10%; extremely unlikely <5%; exceptionally unlikely <1%.

        because they were reporting results in as scientific and quantitative way possible.  Are you actually insisting that I have to do the same for my blog posts?  Now you are just being deliberately difficult.

        A scientist wouldn't make that and other sloppy mistakes that you have made.

        That was a unnecessarily jerky thing to say.  I am a scientist, and have dedicated my life to climate sciences.  You have read a few websites and maybe scanned a few abstracts and think you are an expert.  You are right that I would never try to publish anything I wrote for a scientific publication.  What I submit is written in a technical matter, generally goes through 7 or 8 drafts, and has long discussions about sources of error and ranges.  You know how many times I edit my diaries?  1.  How many times I edit my comments?  0.  So because of the fact that I don't write my blog posts like scientific papers I am not a real scientist?  The internet would be empty if you held that standard to everyone, including yourself.  

        In addition, the whole point of submitting science to a blog like this is exactly to cut through the clutter, like defining modifiers for the word likely so that the science can be accessible to a general audience.  So yeah, I do simplify some aspects of my post for the sake of accessibility.  And some of those oversimplifications I would never make in a scientific paper.  But I don't have to because I am publishing for people with backgrounds in the field so they understand the complexities.  Most of the people who read my posts will not have much of a background in climate science or even science technical writing.  Some will, but most won't and I have to cut through the clutter for them.

        As a scientist I do have an obligation to the facts.  Which is why I talk about ranges, rather than absolute numbers.  I also want to point out to you, because you seem to have forgotten, that when projecting the future you aren't dealing in facts, you are dealing in probabilities.  

        And as a clarification; I do NOT regret making a comparison between the degree of uncertainty that the field has found itself in to the lower limit of projected human induced climate change.  I do regret not clearly designating it as the lower limit of the projections.  I will edit that now.

        If you have a legitimate question about the science or my interpretation of it, I will be happy to answer you.  But if you are going to continue attacking my writing style and accusing me of saying things I didn't say (or mean to say as is clear from clarification), then don't bother.  I won't be responding to you on this or any other diary.

        All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. - Schopenhauer

        by BlueberryTomatoSoup on Thu Feb 17, 2011 at 08:04:58 AM PST

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