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  1. #81
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    Quote Originally Posted by Father View Post
    The IPCC, just like Tim Flannery, is great at making predictions, but not very good at admitting when they get it wrong.
    Let's kill one misunderstanding. Climate models (like demographic models) do not make predictions, they produce a range of projections, which are based on both the model structures and the input variables of different scenarios.

    The methodological change between AR4 and AR5 means the models use atmospheric concentration of greenhouse gases rather than emissions to produce different projections. This has provided a somewhat tighter range for the higher projections but the overall picture is little changed. It should be noted that for some aspects, such as rising sea levels, the projections are actually worse (due to better observations of land ice).

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    Quote Originally Posted by JohnC View Post
    Which is referring to AR5. The SPM was released last year. WGII is coming shortly.

    This may help you understand what the IPCC is doing.
    http://www.ipcc.ch/report/ar5/

    Did you notice how your link also used the 2 degree figure?

    Global mean temperatures have already risen about 0.9 degrees, with at least a 2-degree rise increasingly likely as carbon dioxide emissions from the burning of fossil fuels and land clearing continue to rise, scientists say.
    It wasn't long ago that the Gillard government was saying that we were looking at 5 degrees C. At least this number is more realistic.

    It'll be interesting to see how they explain this:

    “hundreds of millions of people” will be forced to move because of coastal flooding and land loss as sea levels rise.
    There was a prediction not long ago that we would have already had 50 million 'climate refugees'. We have none. That prediction clearly failed.
    When the IPCC AR5 SPM itself says that absolutely worst case, we are looking at a sea level rise of between 45 and 82 cm by 2100. I can't see how that will displace that sort of number. But hey, I can wait until their report comes out.

    Interesting that they think crop yields will decline. If one looks at what has happened with crop yields over the last few decades, things are only getting better. The bigger threat to food security would be wasting corn crops to run cars rather than feeding the hungry.

    Let me know if you would like some data on crop yields over recent times. I will be happy to provide them.

  3. #83
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    Quote Originally Posted by JohnC View Post
    Let's kill one misunderstanding. Climate models (like demographic models) do not make predictions, they produce a range of projections, which are based on both the model structures and the input variables of different scenarios.
    You are seeming quite pedantic here. Would you care to define both 'prediction' and 'projection' for me?

  4. #84
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    Quote Originally Posted by Father View Post
    You are seeming quite pedantic here. Would you care to define both 'prediction' and 'projection' for me?
    If you think the distinction is "pedantic", then that might explain a great deal of pointless huffing and puffing. This might be a good place to start:

    http://sciencepolicy.colorado.edu/zi.../26/guest.html

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    Okay, having absorbed the meaning of "projection" as applied to climate modelling, it is probably appropriate to look at why we have some confidence that the models should be taken seriously by applying them to already known historical data. In the graphs below the models were run against scenarios both with and without anthropogenic forcing (red with, blue without, black lines are the actual observations).

    model predictions 1.jpg

    This is not only striking confirmation of the effects of human activity, but gives us considerable confidence that the modelling process is capturing real-world events. The same process was run across more detailed situations, with similar results.

    model predictions.jpg

    Here is the key provided for these graphics.
    Figure SPM.6 | Comparison of observed and simulated climate change based on three large-scale indicators in the atmosphere, the cryosphere and the ocean: change in continental land surface air temperatures (yellow panels), Arctic and Antarctic September sea ice extent (white panels), and upper ocean heat content in the major ocean basins (blue panels). Global average changes are also given. Anomalies are given relative to 1880–1919 for surface temperatures, 1960–1980 for ocean heat content and 1979–1999 for sea ice. All time-series are decadal averages, plotted at the centre of the decade. For temperature panels, observations are dashed lines if the spatial coverage of areas being examined is below 50%. For ocean heat content and sea ice panels the solid line is where the coverage of data is good and higher in quality, and the dashed line is where the data coverage is only adequate, and thus, uncertainty is larger. Model results shown are Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-model ensemble ranges, with shaded bands indicating the 5 to 95% confidence intervals. For further technical details, including region definitions see the Technical Summary Supplementary Material. {Figure 10.21; Figure TS.12}

  6. #86
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    Quote Originally Posted by JohnC View Post
    Okay, having absorbed the meaning of "projection" as applied to climate modelling...
    That was one blokes opinion on how the words should be used. The dictionary is a little more straightforward. But, if it makes you feel better, I can change my previous posts from 'prediction' to 'projection' - the point is the same regardless of the word used.

    Quote Originally Posted by JohnC View Post
    This is not only striking confirmation of the effects of human activity, but gives us considerable confidence that the modelling process is capturing real-world events. The same process was run across more detailed situations, with similar results.

    Here is the key provided for these graphics.
    Do you have any better graphs that show how good these models are? Maybe ones that go beyond 2010 with a more appropriate scale for the recent decades.

    I'll provide you one. Please let me know if you think this graph is wrong.



    Is this modelling really 'capturing real-world events'? They have all missed the mark considerably over the last decade and a half.

  7. #87
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    Quote Originally Posted by Father View Post
    That was one blokes opinion on how the words should be used. The dictionary is a little more straightforward. But, if it makes you feel better, I can change my previous posts from 'prediction' to 'projection' - the point is the same regardless of the word used.
    No, you have just convinced me that you are uninterested in anything that does not support your denialism, including basic conceptual distinctions.

    Quote Originally Posted by Father View Post
    Do you have any better graphs that show how good these models are? Maybe ones that go beyond 2010 with a more appropriate scale for the recent decades.
    Repeatedly reposting the same graph in the same thread is also not helpful.

    Everyone agrees that there is currently a pause in global mean SAT; that such pauses are neither unexpected nor unprecedented; and that since they are caused by internal variability of the climate system, they definitionally cannot be captured by an unadjusted CMIP5 model.

    The questions for those actually interested in the science are:
    1. Is there a dominant cause that can explain the current hiatus?
    2. When we factor in that cause, what are the range of projections going forward.

    The research by England et al attempts to answer those questions, best summarised in the following graph:

    england_3a.jpg

    Note that all six projections for 2020 fall within the IPCC envelope. Now the trade wind hypothesis has not yet been proven, but it looks like a pretty robust attempt to answer the relevant questions.

    Your alternative, Father, is simply to intimate that the current hiatus means global warming has somehow gone away, which is a preposterous notion that has nothing to do with rational scepticism.

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  9. #88
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    Quote Originally Posted by JohnC View Post
    Your alternative, Father, is simply to intimate that the current hiatus means global warming has somehow gone away, which is a preposterous notion that has nothing to do with rational scepticism.
    I have never said such a thing. I have only been saying the models have been overestimating the situation. Which they have.
    The science has apparently been 'settled' for years. Yet they are still having to come up with new theories to explain away why the models haven't worked.
    Do you agree that the science is in fact - not settled?

  10. #89
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    Quote Originally Posted by Father View Post
    I have never said such a thing. I have only been saying the models have been overestimating the situation. Which they have.
    The science has apparently been 'settled' for years. Yet they are still having to come up with new theories to explain away why the models haven't worked.
    Do you agree that the science is in fact - not settled?
    On the first point, I can only go by the tenor and content of your posts, including your hope that the Senate rejects all emission reduction strategies.

    As to the second point, no science is ever "settled" but that does not mean many questions have not been answered beyond reasonable doubt, including the role of atmospheric carbon in global warming.
    Last edited by JohnC; 20-03-2014 at 16:36.

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  12. #90
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    Would you care to follow up this request?

    Quote Originally Posted by Father View Post
    Do you have any better graphs that show how good these models are? Maybe ones that go beyond 2010 with a more appropriate scale for the recent decades.
    At least England's graph that you provided shows how far wrong the IPCC has been (the red line vs the black).

    And according to England's 'projections', we should see a substantial increase of about 0.1C in temperature in the next 12 months (2015). With a 0.5-0.6 increase by 2020. I guess we'll see how his 'projection' goes in the near future. The year hasn't got off to a great start for him though.


 

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