Ecologists don’t understand physics

Posted by William M. Connolley on April 1, 2009
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I hate blogs that force you to jump through hoops to post comments, especially when those hoops don’t work. So I could mail Gareth to complain about my inability to comment on “The inner mounting flame” but I’m too impatient, so instead I’ll just post my minor snark here:

It sez: “This is a global event now, and the inertia for more permafrost melt is increasing.” Not good news.

I agree. It isn’t good news. It means that ecologists (or, to be slightly fairer, one particular ecologist) doesn’t understand the difference between inertia and momentum.

Meanwhile, Gareth asks So why are we worried? Take a look at the latest graph of global methane concentrations, and note the strong upwards jag since 2007… And if you do look at the graph, you’ll see an increase of perhaps 20 ppb from 2006-8 ish. Which is about 0.6%/yr. Is that really a strong upwards jag? It looks strong compared to the near-flatness in the previous decade, true. But compared to SRES, it is low.

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  1. #1 thomas hine
    2009/04/01

    inertia and momentum? very interesting

    off topic, talk of phenology is gaining momentum in the blogosphere as the seasons change again in the northern hemisphere/US. i was just reminded of the most striking example of phenology i’ve seen which i saw on your blog – the reaction of the stoat to the snow.

    is that on Wiki yet?

  2. #2 Gareth
    2009/04/01

    All you have to do is log in! My browser remembers those things for me…

    [I logged in several times. It didn't help :-( -W]

    A more exciting example of Katey’s physics (and perhaps chemistry) is in the second “research” video on her web page, where she nearly blows herself up.

    So we shouldn’t worry about the recent increases in atmospheric methane because they’re still lower than someone’s idea of what they might have been, formulated a decade ago? Pull the other one.

    [Nope, that isn't what I said. We should... well, wonder about it, probably. But we should make sure we know what we're seeing - an uptick from a flat graph is easy to misinterpret. Remember alol that stuff from Copenhagen about how everything is turning out worse than the worse preditions? I don't recall anyone standing up and saying "actually the forcing from methane is far lower than the best predictions" -W]

    If the current uptick is linked to the northern wetlands – and Walter’s experiences suggest it probably is – then given the current rapid warming in the Arctic (Lawrence et al 2008) then we have every right to be concerned.

    [Certainly, I'm happy to be concerned, as long as we don't get carried away -W]

  3. #3 Nicolas Nierenberg
    2009/04/01

    Gareth,

    The article you linked to is an analysis of a model. It doesn’t demonstrate “current rapid warming in the Arctic.”

  4. #4 David B. Benson
    2009/04/01

    Nonetheless, it does seem that in studied areas of Alaska and Siberia the permafrost is expressing methane (more than before, methinks).

  5. #5 Gareth
    2009/04/01

    Nicholas: That’s correct. Lawrence et al find that in model runs that exhibit rapid sea ice decline you get significant and rapid warming in Siberia, thus showing that at least one model can match observations. It is already warming rapidly in Siberia. See my post (linked in William’s) and read the Nude Scientist article I link to for a discussion of same, or follow my Arctic tag. There’s also a paper in The Cryosphere looking at current Arctic warming, but I haven’t got the link to hand. I did a similar exercise using NCEP data last Nov.

  6. #6 DrC
    2009/04/01

    Another snark – permafrost doesn’t melt. It thaws. Permafrost nerds freak when you use the em word. Something to do with it being frozen dirt and all.

  7. #7 Gareth
    2009/04/01

    Here’s the paper in Cryosphere I mentioned:
    Serreze, M. C., Barrett, A. P., Stroeve, J. C., Kindig, D. N., and Holland, M. M.: The emergence of surface-based Arctic amplification, The Cryosphere, 3, 11-19, 2009.

  8. #8 Nick Barnes
    2009/04/02

    Isn’t inertia just momentum in the co-moving frame?

    [Wrong units -W]

  9. #9 Nick Barnes
    2009/04/02

    Or maybe momentum is just inertia in a non-co-moving frame. Or something.

  10. #10 Gareth
    2009/04/02

    William, no-one would ever accuse you of getting carried away.. ;-)

    Sorry about your problems at HT – nobody else has reported anything similar. Perhaps create a new log-in? As Stoat?

  11. #11 gravityloss
    2009/04/02

    Inertia vs momentum is *a bit* like mass vs energy.

    Inertia is the “slowness” of an object. In a linear system, it’s mass. In a rotational system, rotational inertia is mass times distance from center.

    Momentum is the “amount of movement” the object has, mass times velocity. One of the fundamental laws of physics is the conservation of momentum (and angular momentum) in a closed system.

    I hope I have these terms right in English. :)

    This is observed even when atoms shatter. A stationary atom or hand grenade has zero momentum. If it is exploded into two pieces, and the heavy piece moves south, the light piece moves north, with more velocity so that the total momentum is kept zero (since momentum has direction, unlike energy, it can be negative in a coordinate system). eg m1*v1+m2*v2=0 so v2=-v1*m1/m2.

    So, the undeground layers can have warming inertia (like they have density, actually probably density is a very good estimator for that), most probably what is meant is heat capacity, that is an intrinsic property of them and that can be changed by changing their composition (add water for example).

    They cannot strictly have warming momentum. The closest analogy to warming momentum for an object would be its temperature.

    As a whole, the idea of warming having momentum is misguided. Heat does not have momentum. If you heat an object with a certain power and stop heating it, the object stops gaining energy (getting hotter) immediately with no delay. What the heat energy can do is spread more evenly, so that effects at various layers are felt even if the original heating source is removed, since the heat has only later propagated to them.

    Maybe someone uses inertia and momentum analogies to describe this heat conduction (and convection?) but it’s not strictly in the original meaning of inertia and momentum, which is very well and unambiguously defined by Newton’s mechanics.

  12. #12 Lance
    2009/04/03

    William,

    Being a sceptic by nature, as are all good scientists, at first I cast a jaundiced eye on your blog. In “denialist” circles you are often derided as the Climate Goebbles of Wikipedia.

    I’ve been lurking here occassionally and you seem to be a rather reasonable chap.

    At least you play fair with the facts and don’t hesitate to call people on alarmist claptrap even when they happen to be climate saints (like James Hansen).

    Of course this could all be a trick to enlist me in the grand socialist eco-conspiracy so I’ll being keeping my eye on you just the same.

    [My aim is to be a hate figure for both sides -W]

  13. #13 Eli Rabett
    2009/04/03

    You lose

  14. #14 Chris S
    2009/04/06

    It becomes increasingly clear to me that most physicists don’t understand ecology either.

    My favourite example is a model of insect dispersal that assumed that insects had no power over their direction of movement once in the air column – an assumption that is patently false even for relatively small insects like aphids.

    As for phenology, the understanding of this seems even worse, as the first comment on this page demonstrates.

  15. #15 thomas hine
    2009/04/06

    It was meant as a joke (and the original posting quite humorous), but still, an animal reacting to its environment.

  16. #16 Raymond Arritt
    2009/04/06

    Speaking of phenology, a certain climate textbook has a delightful typo where it’s spelled phrenology.

  17. #17 thomas hine
    2009/04/06

    very funny

  18. #18 Chris S
    2009/04/09

    @ thomas hine:
    Apologies for the snark, I did find it amusing though that the first comment on a blog post about misuse of a technical term contained a misuse of a technical term, but perhaps that was the point.

    (For those still not sure, the study of periodicity in nature is phenology, stoats behaving cutely isn’t. (I’ve seen them do similar ‘dances’ on warm spring grass))