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Thread: Scientific reticence - sea level rise. Any others?

  1. #1 Scientific reticence - sea level rise. Any others? 
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    This is a 2007 piece from James Hansen saying that scientists should stop talking to the public in 'science-speak' - all hedged about with uncertainties and the kind of statements they make in journal papers - that you can only say what you absolutely incontrovertibly know from data and peer reviewed analysis.

    Just a few snippets ....
    Concern about the danger of `crying wolf' is more immediate than concern about the danger of `fiddling while Rome burns'. It is argued in the referenced discussions that there is a preference for immediate over delayed rewards, which may contribute to irrational reticence even among rational scientists.
    .....
    I believe there is a pressure on scientists to be conservative. Papers are accepted for publication more readily if they do not push too far and are larded with caveats. Caveats are essential to science, being born in skepticism, which is essential to the process of investigation and verification. But there is a question of degree. A tendency for `gradualism' as new evidence comes to light may be ill-suited for communication, when an issue with a short time fuse is concerned.
    ...
    Assuming a nominal `Charney' climate sensitivity of 3 °C equilibrium global warming for doubled CO2, BAU scenarios yield a global warming at least of the order of 3 °C by the end of this century. ..... Actual global warming would be larger as slow feedbacks come into play. Slow feedbacks include increased vegetation at high latitudes, ice sheet shrinkage, and terrestrial and marine greenhouse gas emissions in response to global warming.
    ...
    Reticence is fine for the IPCC. And individual scientists can choose to stay within a comfort zone, not needing to worry that they say something that proves to be slightly wrong. But perhaps we should also consider our legacy from a broader perspective. Do we not know enough to say more?
    ...
    Can the broader perspective drawn from various sources of information allow us to `see the forest for the trees', to `separate the wheat from the chaff'? That a glacier on Greenland slowed after speeding up, used as `proof' that reticence is appropriate, is little different than the common misconception that a cold weather snap disproves global warming. Spatial and temporal fluctuations are normal. ..The broader picture gives a strong indication that ice sheets will, and are already beginning to, respond in a nonlinear fashion to global warming. There is enough information now, in my opinion, to make it a near certainty that IPCC BAU climate forcing scenarios would lead to a disastrous multi-meter sea level rise on the century timescale. (My emphasis.)
    (Comment from me: Remember he said this in 2007. Seeing as the rate of SLR is itself increasing we need to think about this a bit.)

    ...
    There is, in my opinion, a huge gap between what is understood about human-made global warming and its consequences, and what is known by the people who most need to know, the public and policy makers. The IPCC is doing a commendable job, but we need something more. Given the reticence that the IPCC necessarily exhibits, there need to be supplementary mechanisms. The onus, it seems to me, falls on us scientists as a community.


    Note when he talks about the 'referenced discussions' there are 50 or so citations - and I've only read a few of them before. Haven't settled down to go through the lot just now.

    Scientific reticence and sea level rise - IOPscience Worth reading. No nasty technical language or incomprehensible equations. Though you should look at 2. The court case even if you don't want to read the whole thing.

    He's saying this about public statements about sea level rise. Any other topics where you think a bit more plain speaking from scientists could do some good?


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    James Hansen is not the best person to quote in relation to sea level rise. He is definitely an extremist, and his "off the record" opinions stretch the science to breaking point. He has presented the view that sea levels will rise by five meters by 2100. This is based on an estimate of rate of rise in sea level doubling every decade. Since they have been consistently staying at round 2 mm per year for the past 50 odd years, and since they have not increased in the 5 odd years since Hansen first presented this view, I regard Hansen as being somewhat irrational on the topic.


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    Current increase is running about 3mm/year...but thus far no signs of strong increases per year.



    Also important to recognize the distribution of rise will very considerably, places like Western Pacific seeing more (and already being observed) while other places might even see a drop such as around Cape Horn.

    Models are still relatively primitive and using basic parameterizations to estimate the cryosphere changes. Hanson points out the lack of dynamics in the models to come up with his own guess. Pretty important we figure is out.
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    This is based on an estimate of rate of rise in sea level doubling every decade
    Not exactly. He's suggesting that if, and only if, non-linear disintegration of ice-sheets has begun, then slr from that source could double every 10 years. Which would very quickly overwhelm the SLR attributable to expansion by heating.

    Of course, it doesn't really matter. The data from the GRACE satellite tells us that we're losing a lot of ice every year from the ice-sheets. It's not a matter of if, it's a matter of when, disintegration gets going. The fact that Hansen could be 20 or 50 years out on the timing of an identifiable start point is neither here nor there in the greater scheme of things. It might be our grandchildren who see 5-10 metres worth of rise, it might be our great-grandchildren - it might even be their children. But I doubt he's more than 20 years wrong, if he's wrong at all.

    The conservatism of the IPCC on Arctic sea ice, extreme weather, droughts and floods and ice sheet losses is not super encouraging. Their projections on the timing of effects of warming have been pretty poor, even though the atmospheric temperature projections have been pretty good.

    If Hansen had said in his 1988 testimony that the apparent decline in Arctic sea ice would see the minimum volume to 20% of its number most people would have said he was mad, extremist, off his very intelligent chump. (They probably would have said it if he'd predicted loss by 20%.) They said those things anyway. He didn't say it, but he would have been right if he had. He's been right far too often for far too long for his views to be dismissed without serious analysis and careful examination.

    (My view is much the same as someone famous whose name I completely forget. "If you want to see where climate science is, read the IPCC. If you want to see where it's going, read James Hansen.)
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    Quote Originally Posted by adelady View Post
    But I doubt he's more than 20 years wrong, if he's wrong at all.
    My view is that the guy is nuttier than a fruit cake. The IPCC last prediction was 300 to 500 mm sea level rise by 2100. Hansen predicts 5000 mm. This is not a slight disagreement. And there is no sign whatever of the increase in rate of sea level rise that Hansen bases his predictions on.
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    To be fair, even at it's release the last IPCC reports were outdated and being eclipsed by a series of studies released during it's drafting and review phase that suggested they were far too conservative.

    Here's just a taste of the more recent studies.
    A forecast of 0.9 to 1.3 meters based on analysis of temperature and sea levels over the past 2000 years using IPCC temperature projections: Climate Dynamics, Volume 34, Number 4 - SpringerLinkHere's another that projects 0.6-1.6 also using the IPCC temperature scenarios.
    How will sea level respond to changes in natural and anthropogenic forcings by 2100?
    And another that looks at develops an estimate of 0.55 to 1.15 m as a good planning range.
    Climatic Change, Volume 109, Numbers 3-4 - SpringerLink
    Anyhow....well above the last IPCC report but way short of Hanson's projections. None of those above address Hanson's contention that ice dynamic and non-linear collapse of the ice sheets might well make estimates based on current or the past 2000 years woefully inaccurate. Between his unique understanding of climate in general, the largely incomplete paleo reconstructions and observed ice sheet break up that time and again are surprising scientist, I wouldn't dismiss his opinion. I do hope he's wrong though...I just signed a contract for a home 30 feet above sea level that with luck, and healthy living, will be my home for the next 40 years.
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    The last IPCC report notably left out completely the contributions of Greenland and Antarctic ice sheets due to the uncertainties and these are likely to be the largest contributors to future sea level rise. The uncertainties include some possibilities of other than nicely predictable linear rise. When a longer period than the satellite data era it doesn't look so linear -



    I'd be wary of dismissing Hansen as some kind of crank - he's extremely knowledgeable and we would be very unwise to ignore the more extreme outcomes that are still within the realms of real possibility. Like the breakup of the West Antarctic Ice Sheet. It is estimated it would add an average of 5 metres to global sea levels. When effects like the lifting of the underlying bedrock from the mass of ice being removed and the gravitational effects on ocean nearby it gets up to 6 and 7 metres on coastlines such as North America's. Whether this can happen within the next century or be a longer term consequence of what we do over the next century it seems like a real possibility and it seems wise to plan for the worst even if we can keep hoping otherwise.
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    I hope, Ken, you have noted how the scale on that graph is carefully selected to give the false impression of substantial increase in rate. A little dishonest, that.

    And yes, I regard Hansen to be a flake. He is so far out and away from other climatologists that there is no other conclusion to be drawn.

    Sea level rise is obviously of concern. The rate may increase, but a doubling each decade has not happened yet, or any sign it may be about to begin happening. I am happy to accept a possible rise of 500 mm to a metre in 100 years, and even that is well above the rate currently. But 5 metres is in the realm of the crackpot.
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    I hope, Ken, you have noted how the scale on that graph is carefully selected to give the false impression of substantial increase in rate. A little dishonest, that.

    Huh? It follows the common convention of displaying the dependent variable on a scale that represents the range of the data. It even shows the break point at 1.5mm/year to highlight the lower range and alleviate confusion. Nothing wrong with the chart.
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  11. #10  
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    It is also a graphical technique to exaggerate change.
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    Quote Originally Posted by skeptic View Post
    It is also a graphical technique to exaggerate change.
    Sorry, but I find this to be a bit of a ridiculous comment. It sounds like you are liking it to flashing a toy badge and claiming to be US marshals. The scale is perfectly fine for a graph of conventional dimensions and for showing relative rates of increase. Would you prefer a flatter curve where less detail can be seen? The scale is clearly given as well.
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    Kalster

    I said it was also a graphical technique to exaggerate change, which is correct.
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    Quote Originally Posted by skeptic View Post
    Kalster

    I said it was also a graphical technique to exaggerate change, which is correct.
    OK, but you are implying that that is what they are doing, i.e. deliberately trying to exaggerate the change. It just seems like a very presumptuous statement. Sorry, not looking to offend.
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    Never, never argue about graph presentations when I'm around. I go into hysterics when I remember this item from Dr Inferno a couple of years ago.
    DenialDepot: How To Cook A Graph SkepticalScience.com Style

    He'd also done these earlier ones on "graphing". DenialDepot: Arctic News and Global Cooling Update

    My all-time favourite ... DenialDepot: Arctic Sea Ice: Staggering Growth

    The only sad thing is that his output is seriously down this last year or so.
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    ROFL! But wait wait...don't tell me: isn't that "a little dishonest"?
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    Adelady

    I am on your side in asserting that AGW is real. However, in view of the opposition, I feel it is vital not only to be honest with all the facts, but very obviously openly honest. Be honest, and be seen to be honest.

    For this reason, I will oppose anyone who uses any technique whatever to 'massage' the data to make a particular message stronger.

    Your example of the sea ice graphs makes the point. The initial objection in that article, about scale, is valid. Of course, the things the author says later are silly, and dishonest. But using honest scales so that changes can be seen in context, is important.

    Good science is honest science. Leave the propaganda to those who are paid to generate propaganda. Scientists should generate and publish honest data without distortion.
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    For this reason, I will oppose
    anyone who uses any technique whatever to 'massage' the data to make a particular message stronger.
    Skeptic, You're making yourself look bad and giving the impression you aren't familiar with the basics of how to show information.

    It would have been easy to alter the chart if any "dishonesty" were intended; for example:
    making the scale a % of a cherry picked data point (say the 0.3mm/year at ~1935) rate which would look like the 2010 rate had increased by a 1000% since that point. (see wattsup web site for numerous examples);
    or perhaps making it fancy and 3D so the later years, where the value was high visible appeared larger due to perspective;
    or perhaps making the upper boundary with a red line while the lower had a grey one;
    or perhaps just leaving off the 150 label all together!


    But that didn't happen, the legend is clear, the lower value (150) clear and an extra line to indicate the scale break and linear above that point, the data neatly fits within the lower and upper bounds set so the data can be viewed for effective presentation in accordance with standard practice for most technical fields.

    --

    Now can we please get back to a discussion of sea level projections.
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    The graph was lifted from Tamino's Open Mind site and the post it came from is worth a look - that graph being one of several revealing different aspects of sea level rise with the purpose of determining whether there is acceleration. It's an open 'secret' that Tamino is a mathematician with considerable expertise in statistics related to climate change.

    The overall (century-long) pattern is acceleration, plain and simple. But on decadal and even multi-decadal time scales, the data show both acceleration and deceleration, repeated ups and downs that violate the simpleton’s model.
    Certainly Tamino finds statistically significant recent acceleration in sea level rise -

    Note that the recent trend is faster than the “linear trend of the entire time span.” A lot faster. And the increase, once again, is statistically significant.
    Skeptic, if you want to complain that his use of graphs is an intentional effort to exaggerate rather than reveal, go there and do so - I'd be interested in Tamino's response.

    As for the possibility of rapid ice sheet disintegration, my understanding is that it is an area with a lot of remaining uncertainties - the dynamics are not well understood yet and there are elements of it (that I hadn't been aware of) that do seem likely to mitigate against rapid breakup of the West Antarctic Ice Sheet; as it loses mass the sea level around Antarctica will, counter-intuitively, drop rather than rise, maybe grounding it more securely. I also wasn't aware how much the change in mass (and it's gravitational effects as well as change to elevation of underlying continent) will impact sea levels locally. As much as 100m drop for loss of the entire WAIS. Of course that drop adds to sea level rise further away. Jerry Mitrovica's youtube presentation with a look at the physics is a fascinating eye opener .
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    Thank you Ken. That Mitrovica video is terrific. It's one thing that reminds us that there are always more complexities to be found than we can ever imagine ..... while the physics governing the climate system as a whole are pretty straightforward.
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    Adelady, I wasn't aware of how significant local variations in gravity really are to sea level.

    As for James Hansen, I don't see any evidence that he's made stuff up or fails to reassess his conclusion in the face of new information - he (and those he works and publishes with) has made important contributions to understanding climate change. The majority of scientists studying sea level rise may disagree with him about how rapid sea level can be expected to change but they don't count what he says as baseless or claim he is a flake; his recent work on the frequency of extreme temperature events reveals something very alarming and it hasn't been shown to be wrong. As for sea level rise, the paleoclimate records does lend support his conclusions that rapid sea level rise is a real prospect, not imaginary. With that and looking at Grace Satellite data -

    We suggest that mass loss from disintegrating ice sheets probably can be approximated better by exponential mass loss than by linear mass loss. If either ice sheet were to lose mass at a rate with doubling time of 10 years or less, multi-meter sea level rise would occur this century.
    I've had trouble getting more recent Grace Satellite data to see if it is showing continuing acceleration of mass loss as Hansen and Sato expect (and don't claim the expertise to make such assessment myself). Even if Hansen is shown to be incorrect about that and the time scale is - as many other scientists believe - multi-century, what we do in the near future will commit us to multi meter sea level rise. It may take multi century to have 5m or more sea level rise but the way we are going we are laying the groundwork for it.
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    Ken

    The thing about James Hansen is the massive discrepancy between his conclusions and those of other climate scientists. Hansen is one who consistently concludes a much more catastrophic outcome than others. That has not harmed his position with those who want to present a disastrous picture. However, it means he is not in line with his fellow scientists. Perhaps when I call him a flake, this is excessive, but the discrepancy is enough to cause me to feel much suspicion in relation to his predictions.
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    Actually, the biggest difference between Hansen and other scientists is not their conclusions. Very few contest his ideas at conferences and other professional gatherings. The big difference is in what he is, and they aren't, prepared to say in public.

    Another important difference, which applies more now than earlier, is that his scientific reputation and tenure protects him from the sort of thing I quoted above ....

    ....... on scientists to be conservative. Papers are accepted for publication more readily if they do not push too far and are larded with caveats. Caveats are essential to science, being born in skepticism, which is essential to the process of investigation and verification. But there is a question of degree. A tendency for `gradualism' as new evidence comes to light may be ill-suited for communication, when an issue with a short time fuse is concerned.

    (And let's face it. It has to be his scientific reputation. As a public speaker he's not disastrous, but he's not very wonderful either. If you look at his TED talk in front of a supportive audience he did not shine.)

    He is now more or less immune from pressure to modify his statements, a lot of prestigious publications and organisations would be thrilled to get him on their books. And I suspect that people who might apply it to younger or less decorated scientists know very well that he'd be willing to tell the world, however haltingly, about any such 'backroom' pressure if they tried it on him.
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    The thing about James Hansen is the massive discrepancy between his conclusions and those of other climate scientists.
    Most are pretty open in their papers that they aren't considering the Western Icesheet break up as a posibility in their calculations, as does the 4th IPCC report, because quite honestly they don't know enough yet.

    What we do know is we're going to push summer NH high latitude radiative forcing higher than during the Ermian when sea levels rose 5-6.5 meters higher than today (roughly Hanson's numbers). Given the long life span of CO2 in the atmosphere, it's probably not a matter of how much rise we'll see, but of how fast we'll see it. Rather obviously a non-linear response that takes less than a century would be extremely painful to humanity and lots of other high latitude organisms--on the other hand a slow linear melt model, such as we're running on now because we don't know any better takes many centuries and would be manageable by all.
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    I think it's good thing to see a scientist with a high profile shake up some of the assumptions of his colleagues as well as challenge the emissions policy inertia. As far as real world data goes the Grace data is a short series and by itself isn't predictive -



    - but it doesn't stand by itself.Meanwhile ice flow rates are showing acceleration in both Greenland and Antarctica and a period of unprecedented and unexpected surface melt across most of the Greenland ice sheet during the recent NH summer suggests predictions have been overly conservative. Hansen may be actively seeking out those holes in our knowledge that have the greatest potential to exceed current expectations and bring a focus on how much they might do so but I think those are exactly the areas that, with further work, will close the gaps. It would be nice to find those worst case possibilities turn out to be unfounded. But it will be devastating to find that - as happened with the rate of loss of Arctic sea ice - mainstream science is severely underestimating rates of mass loss of the world's largest reservoirs of ice.
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    Well, the big issue for the science is not that they're underestimating ice sheet contribution to sea level rise.

    It was entirely omitted from the SLR projections in IPCC FAR because they (Richard Alley being one of the strongest voices if my memory's right) insisted that there was too much uncertainty.

    So the apparently steadyish SLR projection that everyone outside the field itself works with has no melt component at all. The only thing we've got to work with is the recent speed up in the rate. And that's been confounded, overwhelmed, confused by the huge transfer of water from the oceans to the land during the Australian/Pakistan/a dozen other places major floods a couple of years ago.

    How they're going to detect a melt contribution 'signal' out of an even messier dataset (see Lynx's comment @ 3 above) is a challenge I'm glad I don't have to deal with. I'd love to see someone rework the data they've got and apply it in a climate that was El Nino-La Nina neutral during the last 5 years - therefore no floods in Oz at all and different flood scenarios elsewhere - and see what shows up.
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    Will arctic sea level fall as the arctic ocean's ice melts?
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    Sculptor - I'd say no. It's floating ice that's relatively thin and there is only a small effect on sea levels. So it isn't going to shift a lot of mass from the Arctic to elsewhere. According to Mitrovica in the youtube video sufficient melt from Greenland to raise global average levels a metre would cause a 25m drop nearby and higher than 1m further away. Some of North America, being nearby, would see a drop in sea level as a consequence - which I don't think most people would expect. (Mitrovica likens the common expectation to oceans being like a bathtub which levels out but physics says otherwise). But it won't be a case of Greenland or Antarctica but both - as well as loss of other land ice from Patagonia and glaciers around the world. That they will continue to lose mass isn't in dispute, but the dynamics of how it will proceed and how fast are.

    Adelady, certainly the last IPCC report left it out but I'd be surprised if the next one does.
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    Yes Ken. But I rather think that part of the report could be a major competitor for the "who's got the widest error bars" award.
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    Ken,
    I read much the same about the west antarctic ice ---without the gravity of the ice, sea levels there would lower also.
    Freeing more water to head for the equator, which would slow the earths rotation freeing more water to head poleward?
    Do the counterbalancing ice sheets effect the earth's wobble?

    as/re how fast:
    (wild guess du jour) The melt and sea level rise will come in stages, steps, or spurts---------and will not increase on any sort of smooth curve, exponential or not. (which makes predictions somewhat problematic?)
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    The melt and sea level rise will come in stages, steps, or spurts---------and will not increase on any sort of smooth curve, exponential or not. (which makes predictions somewhat problematic?)
    Exactly. The 800 lb gorilla in the room is precisely that. A lot of people presume that "faster" sea level rise will mean a steeper slope on the curve we've seen so far with expansion due to heating. But it won't be like that.

    The biggest rises will come virtually like a series of small (we hope) floods. Floods that won't recede. If you look at the sea floor around Antarctica there are places where an ice sheet "chunk" could just slide into the water. When that happens to a chunk that isn't already partly in/out of the water, the whole volume of that piece of ice will be displaced instantaneously - just like dropping a huge block of ice into a jug or a bowl.

    So you'll get a once only rise from each such piece of ice - even though it hasn't even started melting and might take years to melt while it floats around on the surface.

    (Whereas sea ice melting has the same imperceptible effect as an icecube in your drink melting.)
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    Sea levels have been rising at a steady rate since records began in the late 1800s, well before the CO2 hype era. The IPCC has stated that CO2-based global warming (yes, that's actually what they said: "global warming"...not "climate change"....but "global warming") has only shown up since the 1970s. Thus sea level rise can't possibly be blamed on anthropogenic CO2, can it?
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    Quote Originally Posted by pogomutt View Post
    Sea levels have been rising at a steady rate since records began in the late 1800s, well before the CO2 hype era. The IPCC has stated that CO2-based global warming (yes, that's actually what they said: "global warming"...not "climate change"....but "global warming") has only shown up since the 1970s. Thus sea level rise can't possibly be blamed on anthropogenic CO2, can it?
    I might do you some good to actually read the thread's postings, and figures before you post your own version. Post 7 shows the Sea level rise, which is clearly not at a "steady rate."
    If we look at reconstruction going back much further the relationship remains in even better context:
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    [QUOTE=Lynx_Fox;360627]"I [sic] might do you some good to actually read the thread's postings"[QUOTE]

    Well, I'd never be so crude as to suggest such a thing, but if you in fact feel that your actually reading these thread's postings might do me some good, I welcome the gesture.
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    Pogomutt, the talk by Jerry Mitrovica on youtube is well worth a look; it gives a lot of insight into the physics involved in sea level changes. He shows why simplistic explanations for the supposed steady rise over historic times are inadequate. And how misleading it is to conclude that present sea level rise is therefore not due to climate change. It certainly reveals how deeply (rather than inadequately) current science looks into the factors involved.
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    y'all know what is meant by "a gee whizz graph"
    it is a graph which eliminates certain data to give a false impression(usually about maximums, or rates of change)

    some days, it seems an exercise in futility sorting through the current scientific fad, and "proxy reconstructions" which pointedly ignore any field work(real science) which doesn't tell the preferred story line.

    The marine transgression rapidly flooded the continent since 11,000
    yr BP, and reached its maximum at about 6,000–7,000 yr BP (Wang
    and Wang, 1980). Many deltaic sediment records, like coastal lacustrine
    and salt marshes, tidal flats and shelf deposits testify to strong
    marine and deltaic influences at the Holocene optimum, the absolute
    rise reaching about 2 to 3 m above the present-day sea level (Yang,
    1991)
    http://www.geosocindia.org/episodes/...58%20Zheng.pdf

    and
    Sea level then stabilized at present levels around 6.5 ka from where it has varied by around 1.0 m, with the
    highest elevation being found in Pauatahanui Inlet, near Wellington, of 0.8 ± 0.8 m at 3.8 ka (Gibb 1986)
    http://www.umsl.edu/~naumannj/profes...A%20review.pdf

    etc.etc...
    a little searching and the illusion disolves in a morass of bullshit.

    Anyone who doesn't think climate change will happen/is happening ain't really looking.
    But selling an idea associated with "science" without honest divulging of all the data, including that which contradicts the concept being sold is likely much worse.
    We do not need dishonesty to sell an idea. The truth should be what science is all about. The alpha and the omega.
    Credibility is always on the line. Let us proceed wisely.
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    some days, it seems an exercise in futility sorting through the current scientific fad, and "proxy reconstructions" which pointedly ignore any field work(real science) which doesn't tell the preferred story line.
    You need to be a bit more specific here. If you're going to criticise some scientific work, criticise that piece of work. If you think that scientists don't go out in the field to examine and collect the specimens they report results on, you should tell us which ones are unreliable. If you think that scientists don't risk their safety out on the glaciers, in the caves, on the ocean or in other remote locations, tell us which scientists are making stuff up.

    If you don't know which particular scientist, or piece of scientific work is dishonest ..... don't make vague, scattershot accusations against nothing in particular and no-one in particular. It is not enough to hand wave this away by making some feeble general remark that some, or most, scientists are honest.

    You're accusing dozens of people here of professional malfeasance. Get it right or take it back.
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    Doesn't work, Adelady.

    I pointed out that James Hansen had made an outrageous prediction, substantially more disastrous than his colleagues, and it made his ideas suspect. All that did was cause you, and a couple of other people to jump on my point, and suggest I did not know what I was talking about, and that Hansen was wonderful.

    If his prediction of massive sea level rise, up to ten times greater than his peers, is not suspect in your eyes, then nothing anyone can say, no matter how specific, is going to change anyone's minds.
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    adelady

    The 2 studies I just posted contradict the proxy contained within the graph posted in #32.

    (I had thought that had been/was obvious)

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    If his prediction of massive sea level rise
    How many times does it need to be said.

    Hansen is projecting that once ice sheet disintegration gets started melting will lead to decadal doubling of sea level rise rates. Much more quickly than people have expected until now. If it's already started then up to 5 metres within a century is fairly realistic, but only if.

    The question is whether the ice sheets have, in fact, started to disintegrate. There's not much doubt that continued warming will lead to disintegration, though some people doubted it (or thought it was centuries away) a decade or more ago. We won't know when the start point was until after we see clear evidence of disintegration.
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    Adelady

    I am not disputing ice melt or sea level rise, but the timing. Hansen stuck his neck out and predicted a 5 metre rise by 2100, even though his peers were predicting no more than a metre. My comment was on the reaction of the people on this forum, including yourself, who immediately went into dispute mode.
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    The 2 studies I just posted contradict the proxy contained within the graph posted in #32.
    I've only had a quick look at the methods and stuff - but I have read and re-read the conclusions in both of them.

    At present the measured rate of sea-level rise is much less than that during the last deglaciation; however, catastrophic rise events during this period indicate that much more rapid rates of rise than presently observed are possible
    future climatic changes will certainly be much more abrupt and extended than in the early Holocene, since the last step of deglaciation and the effects of orbital forcing upon the earth continental environments were generally quite slow at human scale, while very rapid at geological time. The following oncoming problems should lead us to pay attention:
    1. Abrupt climatic changes induce a rupture of the present-day stable situation and bring out, before a new stability is reached, severe natural hazards such as extra-tropical cyclones, floods, droughts, land-slides, etc. Such events were already observed at least one decade ago (Flohn, 1987, 1989).

    2. During the early Holocene, human population was scarce and, except in coastal areas and river plains, little concerned with slow climatic change. Instead, the highly populated modern China is liable to be severely affected by the rapid oncoming environmental changes, particularly in the flat deltaic regions like the northern coastal areas of China where even a moderate sea-level rise (estimated to some 0,5 m in 2050) would have severe effects.
    Both are expressed in cautious, conventional, restrained scientific language. I don't see anything here that contradicts any conclusions or projections that SLR is serious, substantial and accelerating.
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    Hansen stuck his neck out and predicted a 5 metre rise by 2100, even though his peers were predicting no more than a metre
    Have a look at the extracts below. All Hansen's projections are qualified by a very big "if". More importantly, a lot of other projections are based on an unspoken "if". That being that continuing along certain paths is best described by a linear function. As soon as you introduce the possibility of an exponential function governing part or all of a climate response, the whole game changes. Recent history is showing us that exponential functions better describe loss of Arctic sea ice and melt from the ice sheets (graphs below).

    Satellites began to measure sea level precisely in 1993. Since then sea level has been rising about 3.1 mm/year. This rate is equal to just over one foot per century. The impact of such sea level change is substantial, yet the concern is that far greater sea level rise will occur this century if the major ice sheets disintegrate.
    from Sea Level

    Ice sheet change is expected to be a "slow" climate feedback. How rapidly ice sheets can disintegrate is one of the most uncertain and imporant climate issues. The dominant physical process causing ice sheet disintegration may be absorption of heat by the ocean (due to an increasing greenhouse effect), resulting melting of ice shelves, and thus an increased rate of discharge of ice from the ice sheet to the ocean. Once this process gets well underway, it may be difficult to prevent accelerating ice sheet disintegration under its own impetus
    from Ice Sheet

    Figure 2 shows that both Greenland and Antarctic ice sheets are now losing mass at significant rates, as much as a few hundred cubic kilometers per year. We suggest that mass loss from disintegrating ice sheets probably can be approximated better by exponential mass loss than by linear mass loss. If either ice sheet were to lose mass at a rate with doubling time of 10 years or less, multi-meter sea level rise would occur this century.


    Graphs and previous quote from NASA GISS: Science Briefs: Earth's Climate History: Implications for Tomorrow
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    Hansen published a graph with sea level doubling each decade beginning 2000. Since sea level rise between 2000 and 2012 continues at 3 mm per year, he is already wrong.
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    Do you mean this one? The Approximations one.
    Fig.6 PDF, PS



    Unfortunately the links above the graph don't work. But my recollection, not swearing on my stack of Harry Potters here, is that this is supposed to show the difference between using a linear and an exponential process to get to a theoretical end point of 5 m total rise within a century. It's not meant to prove anything about reaching 5m within a century. It's supposed to show how difficult working out a projection for the end of the century is from current data if the processes are exponential rather than linear.

    The linear function implies that we should already have seen half a metre SLR by 2012 if such a rise were occurring in such a process with a 5m within a century end point.

    If you look at how the exponential curve just coasts along near zero for the first 40ish years, you can see where the difficulty arises in determining whether such a process has in fact started. You could be absolutely right about the process itself and still have uncertainty for 30 to 50 years whether it had or hadn't started. Or you could be right about it being exponential but if it's at 3% or 5% (and a therefore a different end point for a century) rather than 7% it would be an even bigger range of years before you could detect an unmistakable signal.
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    The graph I had in mind is not that one, Adelady, but was similar.
    As you say, little change can be seen in the first few decades, due to scaling effects. But we all know what exponential means.
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    It seems that as/re the west antarctic ice sheet the thing to watch will be the westerly winds. Warm and moist winds with above average velocity, might well be the indicator for the west antarctic ice sheet desintigration.

    If you add in the possibility that higher temperature surface waters from the indian ocean(which flow into the circumpolar currents) might lend warmth through the gyers to join the offshore current which flows opposite to the 2 outer rings of the circumpolar currents.
    then the peninsula will be hit with a "double whammy", and desintigrate with almost amazing speed.
    If/when that happens, the sea levels will rise, and the flow through the berring sea will increase and add more warm water to the arctic ocean........

    cascade anyone?

    Can you look at the potential changes without the fear?
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    Can you look at the potential changes without the fear?
    Well I don't have much to fear. I'll certainly be dead some time around 2040 if a piano doesn't fall on me in the meantime.

    But I have a lot of regret and concern for how people I've never met will suffer and possibly die because I didn't get my act together with others when it could have done some good. I really, really believed way back in the 80s when I got my solar hot water service that climate change was just another dreary, boring, technical, diplomatic problem like CFCs or acid rain.

    Everybody knows the problem. They all get together and there's a lot of argy-bargy and diplomatic double-talk to save some grubby faces. Then it all gets done within a decade or so. The whole world between 40S and 40N gets their hot water from the sun and all the transport and power generation industries would be in the middle of a change to renewable processes or emissions avoidance processes. But it didn't happen. If I'd known back in the 80s that it could go like this, I would have done things a lot differently.
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    Never say die, even for your great grandchildren.

    Climate change is a slow process. We are talking decades at least, if not 100 to 200 years. Even though we unlikely to stop the warming any time soon, we have the time to adapt. If a species that lived in every climate zone from Greenland to equatorial Africa, even before we had iron tools, cannot adapt to a few degrees average warming, there is something badly wrong. After all, in past geological times, temperatures were anything up to 10 C warmer than now, and life flourished.
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    Quote Originally Posted by adelady View Post
    ... I have a lot of regret ... .
    dread naught dear lady and live a life free of regret.
    Live the best life you can, doing the best you can, and die satisfied, knowing that you could have done no better.
    .............
    (I voted early today---execrising the seeming obligations of a manifest delusion of democracy)
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    knowing that you could have done no better.
    I know I could have done no better now. But I've had good foresight and anticipation about other important things. I'm just sorry I didn't see this particular one coming.

    I might add I'm a lot more optimistic than many others about what's going to happen. This century is going to have a much greater impact on far more people than the two world wars, one pandemic, the Great Depression, the Holocaust and nuclear war had during those 40 years of the previous century. But when we look at how people lived through terrible times, most people in most countries coped fairly well. My mother and her friends went to dances knowing that some of the men they danced with would be killed in combat mere weeks later. When it happened, they cried for a while and went to next week's dance to meet other young men, some of whom faced the same dangers. People got married and had children. They scrimped and scraped through rationing. Things were a lot tougher for people on mainland Europe and in China and Burma, but people there went on with their lives as best they could.

    Earlier, people had seen others drop dead in the street from flu. They went to funerals, they volunteered to help in quarantine hospitals, they did their best and then went on with their lives.

    I expect that people will cope, one way or another, with bad things happening around them and hearing about other, maybe worse, things happening further away. The fact that you cry a bit more often won't alter the fact that you can always make the best life possible for yourself and your family, even if it takes more effort than it could or should have done.
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    I have a much more optimistic view. While climate change will be a major challenge, and cause serious changes to our way of life, I believe it will be less harmful to humans than much of what went before.

    We have passed the risk of nuclear war. We in the western world have mostly fixed the problems of city smog, acid rain, river pollution, Y2K, ozone depletion and so on. In times gone by, very nasty wars killed millions - something that no longer happens. We no longer have more than a tiny part of the slavery, exploitation of peasants, sexual exploitation, forced labour, tortures, evil monarchs, death penalties, forced stealing of people's land and so on. The world is a much better place.

    Plagues and epidemics are a tiny fraction of what was once common. Famines no longer kill by the tens of millions. WWII killed an estimated 55 million people. Nothing like that has happened for a long time. So our children and grandchildren will have to adapt to a warmer world with more extreme weather conditions. Big deal. People are planning colonies on Mars. If that is possible, then living with global warming at home will be a doddle by comparison.
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    Quote Originally Posted by skeptic View Post
    I have a much more optimistic view. .
    as/re optomism:

    2.5 milliom square miles of arctic tundra will be forested---at 500 trees per acre(modest--much of the tiaga is more dense), 640 acres per sq mile.
    that's 800 billion new trees? sequestering about 42 trillion pounds of carbon annually.

    Nature ain't just a nasty negative bitch, most of her feedback and dampening mechanisms are wonders to behold and contemplate.
    And have nurtured us and created the cradle in which our species evolved.

    From what I've read on the subject, it seems that: The largest unbroken temperate forest on earth is the Siberian Taiga. It produces more oxygen and absorbs more carbon dioxide than all of the tropical rainforests combined. In fact, the Taiga contains one-third of all trees on earth.
    ..........soon, and... add in Canada make that 1/2?, 5/8?, or more?

    whither hence?
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    I believe it will be less harmful to humans than much of what went before.
    It could be. I'd hope you're right. But I think our bad management of too many things suggests we're trusting far too much to luck.

    We could avoid a clash between extreme weather production of one or more staple grains in 2 or more major exporters in the same selling season - with increasing demand from increasing population (and population will increase even if we move to below replacement birth rates) - with the same or increased diversion of grain to ethanol, meat and sugar production.

    I suspect that if we avoid major food shortages in the next few decades, it's more likely to be good luck than good management.

    But all bets are off on 'better than last century' if those simmering disputes on the glacier and river water resources involving Pakistan-India-Kashmir-China-Burma-Vietnam come to the boil in an all at once rush.
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    look at where the population is increasing
    and tell me really why you care if people who have 6-8-10-12-14 children on imported food might suffer from their folly?
    .......
    one study I read years ago was church records from a rural part of england, during a spell of bad harvests, young folks were staying with their parents and waiting to wed and start their own families well into their 30s------locally grown(or not)
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    and tell me really why you care if people who have 6-8-10-12-14 children on imported food might suffer from their folly?
    You're a bit out of date with that birthrate stuff. Like 30 years out of date.

    The only countries with really high birthrates are Afghanistan and Congo - frequent violent death in a region leads to high birthrates - along with a few (very few) other countries. Bangladesh is one country that is at greatest risk form sea level rise. And women there have approximately 2 children each. What folly do they have to pay for? Is it their wasteful resource consumption that is causing the problems they face? I don't think so.

    If you haven't watched this before, I highly recommend you do it now. Hans Rosling: Religions and babies | Video on TED.com
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    Good points, Adelady.
    Just let me say one other thing. Bangla Desh has a very rapid level of economic growth. Over the last 10 years at more than 5% per year. I doubt that Bangla Desh is going to be terribly dependent on agriculture long term. The people will do what peoples everywhere have done, and concentrate in the cities. City incomes nearly always exceed those of small farmers. They will buy their food, and the loss of even a large part of their low lands, while nasty, will not lead to social collapse.
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    Quote Originally Posted by adelady View Post
    If you haven't watched this before, I highly recommend you do it now. Hans Rosling: Religions and babies | Video on TED.com
    Another one for my kit bag...thx.
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  59. #58  
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    Fertility rates:
    Bangladesh 2.83
    niger 7.19
    Guinea Bissau 7.07
    Afghanistan 7.07
    Burundi 6.80
    Liberia 6.77
    DR Congo 6.70

    etc>
    List of sovereign states and dependent territories by fertility rate - Wikipedia, the free encyclopedia
    or
    Total fertility rate - Country Comparison

    Only 30 years out of date?
    'tain't 1/2 bad:
    I've done worse.

    nice vid
    I saw it awhile ago,,,still watched the thing again
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    Skeptic, Hansen made a prediction of far more rapid sea level rise than other scientists studying sea level rise; it may be provocative but doesn't, given that he has provided science based reasoning for that conclusion, make it outrageous and suspect. He's raised some genuine questions based on paleoclimate andrecent acceleration of ice sheet loss.

    Ice sheet loss has not, so far, been the biggest contributor to sea level rise but it will become so - that's not so uncertain. How much contribution and how soon retains large uncertainties and, given how serious rapid rise in sea level would be for humanity, I think Hansen has done a service by bringing attention to the potential for near future harm. It's important to know. It doesn't make Hansen correct and he doesn't appear to have convinced the scientific community that it will be that rapid, and on balance that's good. But it is important to have an improved understanding of how ice sheets will respond to the ongoing imbalance in heat in to heat out of our climate system; not only how much sea level rise over the next 87 years but of where that point of no return is that will see ongoing ice sheet loss become effectively unstoppable.

    Meanwhile what I see here is Hansen being castigated for finding scientific cause to think sea level rise will be more rapid than the consensus scientific view by someone who, with no scientific cause, is choosing to believe the combined impacts of climate change will be much less problematical than the consensus scientific view.
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  61. #60  
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    Am I seeing something that ain't there?

    Or, Does Hansen invariably obfuscate anything that interferes with ideas that he is trying to sell?

    Almost all paleoclimatic evidence points to at least 2 (likely 3-5) warmer periods within this interglacial, with attendant higher sea levels---from studies in various places from new zeeland to china to norway. And Hansen's comments about medieval warm period-"not global"------would you call that clarity or obfuscation?

    as/re the eemian
    over a dozen studies have indicated high latitude temperatures to have been 4-9 degrees above current. Interestingly, a few bog and lake pollen studies seem to indicate that at 40-45 degrees north, the temperature and climate were very much like today's. Hansen's comments would have you assume that the world was "likely" only 1 degree warmer then. clarity? or obfuscation?

    I've never been satisfied when hyperbolic speakers try to tell me what to believe in science, nor religion, nor when buying a used car.
    Ignoring the used car salesman for the moment.
    I prefer to expect more from scientists and religious leaders.

    Knowledge shared?
    or knowledge pared down for the easily led?
    Last edited by sculptor; October 24th, 2012 at 05:30 PM.
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  62. #61  
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    Or, Does Hansen invariably obfuscate anything that interferes with ideas that he is trying to sell?
    Look, I know you disagree with various people and various scientific conclusions and activities.

    Can you please learn to disagree without attributing mysterious motives to people you don't know or accusing people of being deceitful or dishonest or in some other way underhanded.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  63. #62  
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    All honesty attempted.
    I would prefer an explanation/clarification of Hansen's comments that would change my perspective.

    So anyone with insight into his reasoning, please chime in.----this ain't about future scenarios, this is about how he differs in his views of paleoclimates from the paople doing the field work.

    Why his dismissal of the medieval warm period, or eemian temperature ranges?

    Adelady, please address the concerns mentioned without impugning my motives............
    If i knew Hansen's motives, then they wouldn't be mysterious would they?

    I'd rather have his reasoning, but would settle for his motives.
    (motives? in a scientist? other than pursuit of knowledge? jeez what has the world come to?)
    (sigh)
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    Science.
    If you want to know about Hansen's knowledge of paleoclimate, I would have thought you'd have read (and re-read) some of his relevant work. Given your interest in the Eemian, you might like to look at page 17 of http://arxiv.org/ftp/arxiv/papers/1105/1105.0968.pdf

    Prior interglacial periods that were warmer than the Holocene can play a key role in assessing the dangerous level of global warming. As shown in Fig. 2d,e, the interglacials peaking near 125 and 400 ky ago (Eemian and Holsteinian, known in paleoclimate literature as Marine Isotope Stages 5e and 11, respectively) were warmer than the Holocene. However, the ice cores and ocean cores do not seem to agree on how warm those prior interglacials were. So we must first consider the differences between these two paleoclimate records.
    Here are some temperature graphs from that paper. (I presume your earlier reading on paleoclimate means that you know that "before present" means the middle of the last complete century - so 1950.)






    All the temperature, gas and other graphs from this item are here http://www.columbia.edu/~mhs119/Milankovic/ if you want to print them off and keep them handy while you read rather than constantly flipping backwards and forwards on the screen. (Irritates the death out of me so that's what I do.)

    Motives.
    He's always been a scientist (though not initially much interested in climate) so no motive other than normal physicist geekdom.

    For his motives in terms of activism, Storms of my Grandchildren would be your prime source. I've only ever read extracts.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  65. #64  
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    Thanks
    I already saw most of those graphs, stored some on this computer years ago. And read the article.

    You may note the temperatures for the eemian and holsteneinian on your bottom graph which show less than 1 degree above current for both?.
    Which has been contradicted for high latitudes by studies I have previously posted----eg: the lake E study for the holsteinian

    Hansen, Sato,et.al. go on to say:
    ... The Antarctic Dome C ice core, with the approximation that global temperature change on millennial time scales is half as large as polar temperature change ...
    meanwhile, we see much higher temperatures recorded in the recent and current studies
    so--------Julie said lake e area was 8 degrees warmer--
    and hansen et al. said that global temperature changes were 1/2 that of the poles.......
    the simple logical conclusion would be to expect average global temperatures to have been 4 degrees warmer-----yet hansen said 1 degree, your chart shows less than 1 degree

    which brings us back to my previous query
    Why the disparity between the field work and this digested material?

    and the counterpoint I mentioned about 40-45 degrees latitude studies for the eemian

    ----------------
    the more people study something, the faster the assumptions/paradigms/etc,... need to change?

    most of those graphs are rather old
    maybe they should be updated with the latest material?
    (long ago, as a student, I learned to "go to the stacks" and read the latest abstracts for the subject under study, then ask the reference librarian(really nice helpful woman) to get me a copy of the article, or disertation)
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    Remember the "current" temperature in a paleo graph is from 60 years ago - well, it's actually the mid-century average if you want to be picky. We've exceeded the 20th century average every month for 331 months now - that's 27.5 years.

    most of those graphs are rather old
    Well, the note on the graph page says the last update was in July last year. I don't know what your definition of 'old' is, but the only updates needed would be from research because recent temperature changes can't affect temperatures recorded decades ago.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  67. #66  
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    no
    but the graphs do not reflect the lake E data which was released in July.

    are you being intentionally obfuscatory?
    do you understand the disparity reflected in the above?
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    Well. I think that a lot of people are working on all the more recent results in all sorts of areas ready for IPCC 5. This July publication would have made the cutoff for inclusion in the report. And there would have been a couple of dozen others this year, along with I don't know how many since the mid 2006 cutoff for the previous report. Not being a scientist, I'm resigned to waiting to see how people who know what they're doing fit this data in with all the other data collected from around the world.

    I just checked the paleoclimate chapter (6) from IPCC FAR. From A to B (of lead author names) of papers cited I counted 79 papers - and gave up - not going to go all the way to Z (there's more than a whole screen of 'P's alone). References - AR4 WGI Chapter 6: Palaeoclimate
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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    "not being a scientist"..............
    but, as a reasonably intelligent human being:
    Do you honestly think Greenland could have/would have melted with less than a 1 degree rise?

    Does that make any sense at all to you?
    It certainly doesn't to me
    ergo my comments and questions
    ...............
    edit, here's another
    we know that oetzi's glacier formed after he died, and is only now beginning to melt.......ergo, it must have been warmer than today 5000 years ago(at least in the alps)
    ..........
    ?
    (but then again, I could be wrong)
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    If you're talking a 1C atmospheric temperature rise maintained for a few centuries with associated warming of the oceans, I expect it's possible. I'd need to know a few other things beside - like what's the start and end temperature, how many centuries, initial sea level and the like.

    But looking at how much Arctic sea ice we've managed to get rid of in a mere dozen decades with only a 0.8 rise, I can't see why maintaining that for centuries wouldn't lead to undercutting and floating off the ends of the glaciers. And once that happens, given Greenland's geography, the glaciers flow faster, the seawater gets underneath and then into that interior area which is partly at sea level and entirely lower than the surrounding higher ground and just lifts the ice off its base. And with no packed sea ice to hold it back, it'll just float away after a couple of decades or centuries. Presumably with a lot of pushing and shoving to be first down the nearest glacier valley.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
    "nature is like a game of Jenga; you never know which brick you pull out will cause the whole stack to collapse" Lucy Cooke
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  71. #70  
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    I get the feeling that yer grasping at straws babe
    You already know that the lake El'gygytgyn studies indicate a temperature 8 degrees warmer during mis11(holsteinean)

    grounded ice takes a heck of a lot longer to melt than sea ice or a heck of a lot higher temperatures/ and precipitation as rain---west antarctica being both---mostly grounded below sea level----------watch for a warmer south pacific and those aforementioned westerly winds.

    and an ice flow bigger than most urban areas
    ramming it's way through the drake passage seas between the antarctic peninsula and south america, or cruising up the west coast of south america
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    Grounded ice doesn't need to melt to affect sea level - it only needs to slide or to be lifted away from its 'grounding' ridge or other geological base onto the water to have an effect on water levels. Anything that's grounded below sea level is already set to slide away from its continent once that grounding separates and to allow water beneath more glacier or ice sheet further inland. Once it's floating it can take decades to melt - the sea level damage is already done.

    If we're talking 8C warmer at the poles then we're talking the possible end of coasts, agriculture, cities as we know them. It really depends on the distribution of higher temperatures. Higher temperatures at the poles can mean slowing Rossby waves and creating more intense drought and flood conditions in temperate regions as we've seen in a few places the last couple of years. But there may be times when polar warming could be much more extreme than anywhere else which might, for a while, maintain or hasten the pace of the winds and moisture streams that support agriculture.

    As we are now, the tropics don't vary much historically and they haven't yet shown as much in the way of warming. The temperate latitudes are pretty vulnerable to shifts in the boundaries of Hadley cells expanding American, African and Australian deserts. That's where the severest effects will occur if there are temperature increases commensurate with the polar regions. So far in Australia, the desert-prone boundary seems to have shifted 20-50 km further from the equator. If it shifts much more, a good part of our dry wheat-growing climate will finish up in the Southern Ocean. As for other temperate issues, America's already had to shift all its hardiness zones for plants by about half a zone on average. The poles. More heating, more melting, less snow cover, more sea level rise, more warming from more exposed waters and more exposed soils.

    I don't see large bergs or larger areas of ice cruising up the sides of South America in the way that bergs from the Arctic drift down to the Atlantic. The Antarctic circumpolar current could well change under these influences but it's a very big, very powerful feature of the oceans. It will still flow round the continent - certainly strong enough to keep most of the ice on course in that general below 40S latitude. The roaring 40s aren't likely to quiet down without a fight.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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