May 17, 2009 | Ronda Jambe

Sloshing around in the greenhouse

This morning I clumsily misjudged how full my coffee cup was, and some splashed on the startled cat. I thought I could manage it while walking and carrying a newspaper. This trivial blunder reminded me that our tendency to think in straight lines, lines of logic and control, must be hardwired into our brains.
Maybe that’s why boxes, rather than Gaudiesque curves, dominate our architecture. Since I’ve visited Sagrada Familia, I’ve seen spin-offs in a few places, including a town in Victoria off the Hume Highway, and this little eco village in Costa Rica:
gaudi room CR.jpg
We humans love to make a splash, let others know about our delight in the natural world. But physics doesn’t care about our esthetics or our engineering. Even though I am nearly obsessed with non-linearity, I have been thinking (logically, I presumed) that a one metre rise in sea level would make the road out to Moruya Heads a bit dicey at high tide. But a new report shows how narrow and imprecise this kind of thinking is.
The oceans, our blue treasure (I got that from a recent Spanish lesson about El Tesor Azul) cover most of the planet, and they make our globe a large bowl, whose basin is gravity. Now scientists believe that the way the water sloshes in this global bowl will be profoundly affected by melting ice caps, and the news is not good.
North America will experience a disproportionate sea level rise, about 25% more than the global average. Here it gets complicated, but it comes down to less mass in the Antarctic due to less ice, and therefore weaker gravity in the Southern Hemisphere. This will cause water to ‘pile up’ in northern oceans.
This, in turn, will alter the distribution of the Earth’s mass to such an extent that the rotation of the planet would alter, and cause water to slosh onto North America. An article about this report is at:
Just another human blunder, a misjudgment of our impacts, our power, our influence. Paul Krugman has recently been to China, and says they will have to cut back their coal-dependent emissions, even if it takes tarriffs on the products they produce to make them clean up their act. I wonder if Rudd has taken this possibility into account, when assessing Australia’s optimistic growth projections. Maybe he should be paying attention.
Meanwhile, I will continue my own splashing, I call this one ‘birth canal’:
birth canal small.jpg

Posted by Ronda Jambe at 7:32 am | Comments (4) |
Filed under: Environment


  1. A few more things to add to the mix Ronda…
    First we’ll need to add and define ‘almost infinitely sensitive’.
    Secondly, the spherical nature of our planet is not in question, as we’re considering resultant lines of force from the planet’s gravitational field. So whether the Earth is a ‘perfect sphere’ or flat at its poles (or oblate, which it is) doesn’t affect the distribution of water on the Earth’s surface, as the water mass fits into whichever form our planet takes?
    It’s also important to remember the Earth’s oblateness is a result of rotational forces which don’t directly influence the generation of gravity, which itself is produced in every atom in, on and above the Earth’s surface.
    So measurements of variations or distortions in gravitational fields (and localised anomalies) can’t fully account for a ‘lop-sided’ distribution of liquid water within the ocean’s basins, which are implicitly local and anomalous, therefore would not cluster in the Northern hemisphere. That’s like tipping a glass of water on it’s side and expecting the water to pool at the top?
    FWIW, much of the anticipated sea level rise is expected to be a result of a warming ocean which, like any other form of matter, expands when heated.

    Comment by Davide — May 26, 2009 @ 7:39 am

  2. Darn! I accidentally deleted the previous comment, with all the spam. The science students agreed with you, Davide, that ‘sloshing’ on our huge planet is not possible, given the molten core and its gravitational pull.
    I only know what the scientists tell me, I trust them more than financial advisors, who seem to mostly get it wrong.
    I also think we humans face hubris if we think we can alter the planet the way we do and not face consequences as we reach the limits of our knowledge.
    However, I believe you have at least one detail wrong: water is not like all substances, and has a non-linear expansion/contraction profile. Depending on the temperature range, it contracts or expands. It actually expands when it freezes, see

    Comment by ronda jambe — May 26, 2009 @ 8:01 am

  3. The initial idea (regarding the ice sheet atop the Antarctic land mass) may be right, as it does have a greater volume than the same amount of water. Less density as well, owing to the atomic arrangement of water ice crystals.
    Due to this, ‘expanded’ water’s (ice’s?) position on land would not, and could not influence, global sea levels. That is, until it slips and drips into the sea, of course.
    At which point it will eventually become melted ice (that is, water) so the non-linear profile becomes inconsequential.

    Comment by Davide — May 27, 2009 @ 2:42 pm

  4. The initial idea (regarding the ice sheet atop the Antarctic land mass) may be right, as it does have a greater volume than the same amount of water. Less density as well, owing to the atomic arrangement of water ice crystals.

    Comment by Stainless steel Bangle — June 9, 2009 @ 8:28 pm

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