The IPCC Fourth Assessment SPM

“Dynamical processes related to ice flow not included in current models but suggested by recent observations could increase the vulnerability of the ice sheets to warming, increasing future sea level rise. Understanding of these processes is limited and there is no consensus on their magnitude.”

Note that some media have been comparing apples with pears here: they claimed IPCC has reduced its upper sea level limit from 88 to 59 cm, but the former number from the TAR did include this ice dynamics uncertainty, while the latter from the AR4 does not, precisely because this issue is now considered more uncertain and possibly more serious than before.

On the hurricane/tropical strorm issue, the language is quite nuanced, as one might expect from a consensus document. The link between SST and tropical storm intensity is clearly acknowledged, but so is the gap between model projections and analyses of cyclone observations. “The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period.”

We will address some of these issues and how well we think they did in specific posts over the next few weeks. There’s a lot of stuff here, and even we need time to digest it!

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364 comments on this post.
  1. greg meyerson:

    hi: did anyone here read the recent article (2/13) in the ny times by john tierney on the richard branson offer of 25 million to invent a carbon eating technology?

    in the course of that report, the author made assertions about the ipcc report–suggesting among other things that the issues around sea level rise are hyped and that we will see only slow changes, nothing rapid, no tipping points.

    I think that in his discussion of sea level rise he may have made the mistake referred to above–he asserts that predictions of sea level rise has gone down (instead of making the point above about apples and oranges comparison where one measurement leaves out dynamical effects)

    anyway, are there any serious criticisms the experts here would make of this article, either on grounds of interpreting the ipcc report or on plausibility of seeking out miracle (carbon eating nano) technologies to deal with global warming as a substitute for reducing ghgs?

    thanks

    greg

  2. Barton Paul Levenson:

    [[Thank u very much for your kind response. But i just want to tell u that i’m not afraid of all these earth changes. i was just eager to know what’s going on… Moreover, my main hobby is collecting information about earth, beyond space, the unexplained phenomenon, black holes, Bermuda Triangle, underworld civilizations & several other spots that has wierd science & mysteries behind it. I hav been doing this for about 5yrs(since i was 14), but i have’nt got any clear evidences.]]

    All interesting stuff, but not really relevant to this blog, which is mostly about global warming. If you want to e-mail me about any of this I’ll try and tell you what I know, which may not always be much. :)

  3. Priya:

    Yes, i know Barton. These are really not relevant to this blog. But i tried through email. It did’nt reach u…

  4. Barton Paul Levenson:

    [[Yes, i know Barton. These are really not relevant to this blog. But i tried through email. It did’nt reach u… ]]

    It reached me, I just didn’t have anything to say in response.

  5. Danny:

    Global Warming is bad! =]

  6. mark:

    i,m not a scientist and not really up on all the jargon that they use….after several years of listening to theorys about how the planet is being destroyed,my thoughts have dedused a theory of my own,one that i have not heard anyone comment on before,maybe i am not well read enough or it is something that may have been brushed under the carpet..so to speak….not dismissing that polution and all the other things that have been commented on help,but to me it seems the rapidness over the last 30 years of global warming coencides with mans overwhelming desire to venture into space….now as i said,i am no scientist but,if you continually keep breaking through the atmosphere with rockets and satalites,not only are you burning all that fuel so close to the ozone layer….the thing they say which is causing the problem….maybe momentarily you are creating a hole,all those harmful radiations must be able to get through?how many and how many times have we done this?this has got to weaken our ozone layer surely?how many planes are flying in the skies now?burning all that fuel so close to the ozone,think we need to look higher to solve this problem we have…..dont you?

  7. Barton Paul Levenson:

    [[if you continually keep breaking through the atmosphere with rockets and satalites,not only are you burning all that fuel so close to the ozone layer….the thing they say which is causing the problem….maybe momentarily you are creating a hole,all those harmful radiations must be able to get through?how many and how many times have we done this?this has got to weaken our ozone layer surely?how many planes are flying in the skies now?burning all that fuel so close to the ozone,think we need to look higher to solve this problem we have…..dont you? ]]

    It’s an interesting idea, but I don’t think the holes created by spacecraft last long enough to have an effect on the planet’s climate. That, and consider how physically small they are compared to the size of a planet. The biggest spacecraft out there in terms of width might be the US space shuttle, which is what, 50 meters across? Compare that to an Earth with an area of 510 trillion square meters. Similar comments for airplanes, I think, although of course there are a lot more of them.

  8. yartrebo:

    Re #356:

    At the present time, there aren’t enough spacecraft launched per year to have any major effect, but I do believe that airplanes have an effect on ozone levels via their stratospheric emissions.

    If space travel becomes much more frequent, perhaps because of space tourism, then it does have the potential to cause serious harm as it is orders of magnitude more harmful per passenger or per kg of payload than commercial aircraft flights.

  9. rick hanheide:

    I’m trying to read the SPM and got all the way to page 5 before getting stuck. Table SPM-0 is a list of sources of sea level rise (thermal expansion, glaciers and ice caps, Greenland, and Antartica, with numerical values for each). The next line is “sum of the individual climate contributions to sea level rise”. I was expecting that to be the “sum” of the four listed components, but it’s certainly not.

    I’m sure you have noticed and explained this already – please just point me to where..thanks

  10. rick hanheide:

    Hmmm. Maybe no one is reading this topic anymore. I’ll try my question on a current discussion.

  11. WJG:

    What sort of people work for the IPCC? [edit]

    Page 5 of the summary, the first table, none of it makes any sense. First, its in meters, then they sum up the results in millimeters and exxagerate the numbers by a factor of 10. Then, the estimated contributions to sea level rise, simple do not add up. Just do the math.

    Are the authors and everyone, everyone that reviews the summary making up numbers, or are they unable to do simple math? In addition to models being completely wrong. Conversions do not make sense, addition is wrong, coupled with a wild model that is no where close to the observed rate.

    0.18 meters is 1.8 millimeters?

    0.16+.077+0.21+0.21 = 0.28?? (coincidenatlly close to the observed rate?)

  12. WJG:

    my mistake – the authors made a table on a scale of 100 years, while discussing the result son a scale of one year.

    However, it still stands that the math does not add up.

    Do the reviewers own a calculators? As it stands – the summary for sea level can only be discarded because no one in the IPCC can do math.

    [Response: See comment #11. This typo is already fixed in the downloadable version. -gavin]

  13. Henk Lankamp:

    @Rick and WJG
    Please download a newer version. At first there was a mixture of units in the table, this is corrected now, all values in mm/yr: SPM2.

  14. Dan:

    re: 361 and 362.
    It is not all that difficult to do a quite simple search here at the top of the page and find the SPM reviewers are listed in post 48 at http://www.realclimate.org/index.php/archives/2007/02/fraser-institute-fires-off-a-damp-squib/

    So you can now contact through Google Scholar each scientist listed and specifically ask them if they are “making up numbers” or “are (you) unable to do simple math?”.