Lack of Environment

A blog on the politics and psychology underlying the denial of all our environmental problems

Why Table 12.4 of IPCC AR5 should not be trusted

with 23 comments

At the end of September, Working Group 1 (WG1) of the International Panel on Climate Change (IPCC) published the first part of its Fifth Assessment Report (AR5).  This report, entitled ‘Climate Change 2013: Physical Science Basis’, now has its own website, from where the Summary for Policy Makers (SPM) and Full Report (chapter-by –chapter) can be downloaded (as PDF files).

Observers of contrarian cyberspace will have noticed that a certain Table in the full report (Table 12.4) has been widely touted as proof that climate change is no longer the problem “alarmists” think it is.  Even high profile professional people (who ought to know better) have demeaned themselves by publishing guest posts on unscientific websites: e.g. ‘Understanding the IPCC AR5 Climate Assessment’ by Professor Richard Lindzen on WattsUpWithThat.

AR5 Table 12-4

The problem with such a mis-reading of the speculative data in Table 12.4 (summarising ‘Components in the Earth system… susceptible to abrupt or irreversible change’ on page 12-78) is that it completely contradicts the historical data in Table SPM.1 (summarising ‘Observed Changes in the Climate System’ on page SPM-23).

AR5 Table SPM-1

Whereas Table 12.4 suggests climate scientists consider it improbable that a variety of catastrophic tipping points will be passed in this Century, Table SPM.1 indicates that they have generally high confidence that we are already witnessing increased frequencies of various unusual weather events.

Thus, trying to use Table 12.4 to suggest that anthropogenic climate disruption (ACD) is not the massive problem the IPCC has confirmed it is (with 95% confidence), is one of the most shameful pieces of cherry-picking I think I have ever seen.  As with his mis-use of graphs in his presentations to the already-sceptical, this suggests that Lindzen knows what he is doing and is deliberately trying to mislead and or misdirect people.

As I would not just want anyone to take my word for it, I have reproduced within this post both tables and the text that accompanies them in their respective reports.  However, rather than start with Lindzen’s shameless cherry-picking of Table 12.4 and attempted inversion of the IPCC’s position, which would only confuse people (as I suspect is his intention), perhaps I should have started with the facts as presented in the SPM.  If so, I can only apologise and now attempt to redress the situation.

As is the way with everything else, the SPM has been reduced to a series of Headline Statements (PDF available here).  However, such sound bytes are very useful and, in the current context, the most relevant are as follows:

  • Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence).
  • The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m.

I should also wish to draw your attention, noting that a gigatonne (GT) is roughly equivalent to a cubic kilometre of ice,  to the following sound bytes from section B.3 of the SPM regarding the Cryosphere (page SPM-7):

  • The average rate of ice loss from glaciers around the world, excluding glaciers on the periphery of the ice sheets, was very likely 226 [91 to 361] GT/yr over the period 1971−2009, and very likely 275 [140 to 410] GT/yr over the period 1993−2009.
  • The average rate of ice loss from the Greenland ice sheet has very likely substantially increased from 34 [–6 to 74] GT/yr over the period 1992–2001 to 215 [157 to 274] GT/yr over the period 2002–2011.
  • The average rate of ice loss from the Antarctic ice sheet has likely increased from 30 [–37 to 97] GT/yr over the period 1992–2001 to 147 [72 to 221] GT/yr over the period 2002-2011.  There is very high confidence that these losses are mainly from the northern Antarctic Peninsula and the Amundsen Sea sector of West Antarctica.

As noted on page SPM-7, 100 GT/yr of ice loss is equivalent to about 0.3 mm/yr of global mean sea level rise (SLR).   It is perhaps also worth noting, here,  that SLR is currently 3.0 mm/yr (and accelerating all the time).

If your head is already spinning with all this data, just try to focus on one fact:  The SPM contains two numbers for decadal average melting rates in Greenland, namely 34 GT/yr in 1990s and 215 GT/yr in 2000s.  As we shall see, these numbers not only bring into question the cherry-picking of Table 12.4; this six-fold increase in ice loss in just 10 years suggests that the conclusions stated in Table 12.4 are incompatible with what is already happening.

As every teenager knows, you cannot confidently draw a straight line through anything less than three points on a graph.  However, we are not dealing with a linear relationship here and, if we were, the above numbers (i.e. 34 and 215) would imply Greenland had been gaining ice prior to the 1990s (which it wasn’t).  This therefore gives us even more confidence that the annual rate of ice mass loss in Greenland has accelerated.

Indeed, perhaps the person who compiled Table 12.4 should have consulted Wikipedia:

  • 1961 to 2003:   +25 to –60 GT/yr => 1982, –18 GT/yr
  • 1993 to 2003:  –50 to –100 GT/yr => 1998, –75 GT/yr
  • 4/2002 to 11/2005: mean 215 GT/yr => 2004, –215 GT/yr
  • 3/2002 to 9/2012: total ~2900 GT => 2007, –276 GT/yr
  • 2008 to 2012: mean 376 GT/yr => 2010, –367 GT/yr

Table 12.4 expresses high confidence that the disintegration of Greenland ice sheet is exceptionally unlikely in this Century.  This may be because the total volume of ice (i.e. If 2,850,000 km3) is so large.  However, at what point does the accelerating ice loss become catastrophic (especially if it is already irreversible in any timescale relevant to human civilisation)?

It must be accepted that the accelerating ice mass loss will eventually reach a maximum rate (due to the finite amount of solar radiation (etc) and then decline as surface area declines.  However, it would seem unwise to assume we have reached that point already.  That being the case, the disintegration of the Greenland ice sheet is already happening.  In my opinion, this is a catastrophe – we just haven’t had to deal with the consequences yet.

Either way, how can the IPCC ignore the fact that the melting of the Greenland lcesheet is already accelerating?  As it is almost certainly already beyond our capacity to stop it, this makes the relevant entry in Table 12.4 seem counter-factual.

Given what Joe Romm has called the ‘planned obsolescence’ of the AR5 – as a result of systematically ignoring the effects of positive feedback mechanisms that are already observable – I suspect that the same is true for all the other entries in Table 12.4.

Given all of the above, it is even more ludicrous to try – as Lindzen and others have done – to  use Table 12.4 to falsify the basic position of the IPCC, which is that ACD is already happening and already accelerating; and the longer we wait the harder it will get to stop it.

Written by Martin Lack

3 November 2013 at 00:02

23 Responses

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  1. Zwally, et al., (2012), ‘Mass Gains of the Antarctic Ice Sheet Exceed Losses’, SCAR ISMASS Workshop, July 14, 2012. (PDF available here)
    The Abstract of which reads as follows: During 2003 to 2008, the mass gain of the Antarctic ice sheet from snow accumulation exceeded the mass loss from ice discharge by 49 GT/yr…[As you have provided a link to the PDF, further quotation has been deleted for reasons explained below. – ML]


    3 November 2013 at 04:11

    • That’s a very short time frame catweazle666. It’s only 5 years. The long term trend is an overall loss of ice mass from Antarctica.

      In a landmark study published Thursday in the journal Science, 47 researchers from 26 laboratories report the combined rate of melting for the ice sheets covering Greenland and Antarctica has increased during the last 20 years. Together, these ice sheets are losing more than three times as much ice each year (equivalent to sea level rise of 0.04 inches or 0.95 millimeters) as they were in the 1990s (equivalent to 0.01 inches or 0.27 millimeters). About two-thirds of the loss is coming from Greenland, with the rest from Antarctica.


      3 November 2013 at 08:09

      • Thanks for providing a rational response to Catweazle, Rachel. (I am not sure that such an ironic comment deserved one)

        Martin Lack

        3 November 2013 at 09:42

    • Dear Catweazle, please tell me you were trying to be funny. My post warns against the dangers of cherry-picking data to support a predetermined desirable conclusion and you have responded by doing exactly that. As I really cannot be bothered to repeat myself, please see my response to Oakwood in my previous post (i.e. search for the word ‘Antarctica’). Apart from that, I can only point out that the lead author of this paper (which I suspect you have read about on Mark Morano’s Climate Depot and/or Anthony Watts’ WUWT websites) is well-known in mainstream scientific circles for another quotation:
      “The Arctic is often cited as the canary in the coal mine for climate warming… Now as a sign of climate warming, the canary has died. It is time to start getting out of the coal mines.”

      Martin Lack

      3 November 2013 at 10:02

  2. Excuse my ignorance and the disturbance this might cause in certain quarters but, as we are told in GB that the temperatures “for this time of year are below average”, it follows that the average temperature must be descending, and on a continual basis. Or is this incorrect? Perhaps the scientists involved in this complex matter might just be unaware of all the factors contributing to increase in atmospheric temperature and that, therefore, their computer models might just be askew? Must I now do penance for this aberration or heresy? [No, Duncan, but it would be appreciated if you could stop stating things that are patently false. Please take another look at my ‘Summary of the “Climate Departure” research of Mora et al (2013)‘. – ML]


    3 November 2013 at 09:44

    • Duncan,

      Where have you read that the temperatures are below average for the UK? According to the MetOffice blog, this October is set to be in the top ten warmest since 1910. The other imortant issue is that temperatures in the UK are not representative of global temperatures. We could very well experience a colder than usual winter here while the mean global temperature is higher than average and rising.


      3 November 2013 at 10:12

      • Once again, Rachel, I must thank you for offering such a rational response to Duncan (a.k.a. ‘Thomas Foster’). However, Duncan/Thomas has a track-record of making comments like this (i.e. about CO2, models, temperature, and/or climate scientists) on my blog (see links below). Therefore, I really cannot be bothered to repeat myself any more.

        Martin Lack

        3 November 2013 at 12:56

        • I know how you feel. It does get a bit tiresome:-)


          3 November 2013 at 12:59

    • Dear Duncan,
      I am genuinely grateful for all your supportive feedback when the subject relates to resource depletion, population growth, or environmental degradation in general. However, I must confess I am now very tired of your repetitious and – as Rachel has now also observed – easily falsifiable comments (e.g. regarding carbon dioxide and temperature). Given the high density of climate myths that appear in such comments – and the fact that you do not seem to take on board previous rebuttals of them – you will have to forgive me for not bothering to do so now. In the circumstances, I feel I have no choice but to add you to my Moderation list. Any further such comments may be deleted without warning.
      Regards, Martin.

      Martin Lack

      3 November 2013 at 12:52

  3. So Lindzen drops more scat, not a surprise, see Sou at HotWhopper for more. I think that she would appreciate a nudge on this one.

    At the bottom of each page of that IPCC Physical Science Base document carries this notice ‘Do Not Cite, Quote or Distribute‘. Does that not imply that Lindzen, nor anybody else for that matter, should consider this the final presentation? Or have I missed something?

    Now, I wonder, if the fuzzy wrongness of that Table 12.4 is deliberate to lure out those who wish to cause trouble and thus positively identify themselves? I guess Dickie ‘(rhymes with something)’ Lindzen is sore because he wasn’t asked to be a contributory author. Lindzen, of course does get a mention, but in pasing and in his association with Choi (Lindzen & Choi 2009) runs up against Desseler and Foster.

    It is really sad to see Lindzen, a once respected scientist, descend to posting at WUWT. Where next, join Michaels at Forbes?

    As for ‘the devil’s feline’ and his OT post, he/she may like to search for other more recent articles, the one he sited will not download for me here, and I suggest simply searching on EAIS at RealClimate.

    Lionel A

    3 November 2013 at 16:44

    • Thanks Lionel. As I understand it, this WG1 report has been published (but may be amended betwen now and the publication of the rest of AR5 next year. As such, I believe the message in the footer is now redundant (and relates to the period in which the document was leaked to people like ex-TV weatherman Watts).

      I must thank my cyberspace acquaintance, Bill Everett, for helping me to appreciate the differences between these Tables (and to understand how 12.4 could have been included). Bill points out that the inclusion of Table 12.4 can only be reconciled with evidence of accelerating change (i.e. because positive feedbacks are occurring) by the rather pedantic language it contains: It considers only the possibility of abrupt change in future (i.e. a quantum leap as opposed to gradual acceleration of change).

      However, to me at least, this seems counter-factual: The catastrophe is that humanity has allowed positive feedback mechanisms to be established. After all, what is the difference between the situation we are now in and a ‘Runaway Greenhouse’ effect? Can we reverse the change that is already occurring? Can we slow down the loss of ice from Greenland or increase the amount of snowfall it receives? Common sense tells me the answer is “No”. The best we can now hope for is to prevent the acceleration from continuing (and thereby ensure that adaptation remains a possibility for the majority of life on Earth).

      Martin Lack

      3 November 2013 at 18:54

  4. I’m beginning to understand better now. The IPCC represents the consensus, but that doesn’t stop you choosing which bits you believe. Quite like the Bible then.


    5 November 2013 at 20:14

    • I am not the one, Oakwood, who is treating climate science like a ‘pick and pix’ sweet shop. Whereas you choose to ignore the bulk of the evidence, all I have done is demonstrate that citing Table 12.4 – as you did – to dismiss the rest of the report is incompatible with the reality that numerous indicators of ongoing change are already accelerating. That is not what I call being ‘sceptical’, it is more like willful blindness.

      Martin Lack

      6 November 2013 at 10:41

      • Perhaps you could indicate which evidence you think I’m ignoring.


        6 November 2013 at 12:56

        • Given the content of the SPM – and the accompanying headline statements – from the IPCC (as per the links above), it is very hard to avoid the conclusion that this is just yet more attempted Pythagoras and plate-spinning from you.

          As such, it would seem that you are on a flight from reality because:
          1. The Law of Conservation of Energy (from evaporation) dictates that a warmer atmosphere with more moisture in it more of the time provides more power to generate more storms.
          2. The Law of Conservation of Mass dictates that more rain in one place means there will be less somewhere else.
          3. Analysis of the last 60 years of actual meteorological data for the Northern Hemisphere reveals that the ‘climate dice are now loaded’, which is why we ‘now throw more double-sixes’.

          Martin Lack

          6 November 2013 at 14:27

        • Your points represent theory and opinion, not evidence.


          6 November 2013 at 16:20

        • Scientific Laws and Historical Facts are neither theory nor opinion.

          Martin Lack

          6 November 2013 at 17:36

        • Yes Martin, at least we can agree on that! Also, of course, theory and opinion are not facts.


          6 November 2013 at 21:46

        • Unless I am very much mistaken, your comment is entirely meaningless (and we are agreed about nothing whatsoever). I am in awe of your propensity to produce counter-factual (and/or meaningless) soundbytes. Meanwhile, back in the real world, we have “the 4th Category 5 typhoon to hit the Philippines this year”.

          Martin Lack

          7 November 2013 at 17:01

        • Let me simplify that then. I agree that “Scientific Laws and Historical Facts are neither theory nor opinion.”. So we agree on that.

          Now, I’m not sure of the relevance of your reference to the typhoon in the Philippines. For one who routinely accuses others of cherry-picking, you seem to be suggesting this event in one part of the world is evidence of AGW. There’s nothing new about cyclones in the Philippines.

          The IPCC says “There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration)” (Typhoons are a type of tropical cyclone.)

          Or is this another part of IPCC work that should not be trusted?

          I am also in awe.

          [This comment has been permitted solely because I believe that retaining evidence of the intellectual incoherence or dishonesty of people who claim to be ‘sceptical’ is in the public interest. – ML]


          7 November 2013 at 18:06

        • I will agree that you are unable to falsify the points I made (about the inevitability and observed reality of increasingly-weird weather).

          The Taiwanese Environmental Protection Administration (TEPA) provides a site-specific counterbalance to your tiresome data mining from the now-superseded SREX report from the IPCC. This TEPA report (PDF) indicates that Taiwan was hit by 14 major typhoons in 2000-09, compared to 6 in 1990s; 6 in 1980s; and 4 in 1970s.

          It is you that does not trust the IPCC, not me. I believe the IPCC should be trusted and that cherry-pickers – who have infinite trust in their own cherry-picked ‘experts’ but are entirely distrustful of the scientific consensus that ACD is already happening – are self-evidently being intellectually dishonest.

          As if we needed more proof, along with the incoherence of focusing on a 15-year pause in surface warming but dismissing an 80% loss of Arctic sea ice over the last 30 years, your contribution to this comment thread is another example. Awesome or tragic, I am not sure. May be it’s both.

          Martin Lack

          7 November 2013 at 19:46

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