Poul-Henning Kamp writes: > That reminds me, has anybody tried to do the math on climate change ? > > The main effect is (probably?) going to be the thermal expansion of > the worlds oceans. > > I did a quick back of the envelope calculation modeling the earth > as a sphere radius 6367 km, covered by a 4 km thick shell of water. > > Increasing the thickness of the water by one meter but retaining > its mass, I get a realtive change in angular momentum of 6e-11 which > is in the order of a millisecond per year.
Below is a posting from last year; two plots are attached. It guesses long-term climate LOD variations are on the order of 200 ms (that's leap second every week territory). /tvb ----- Original Message ----- From: "Tom Van Baak" <[email protected]> To: "Leap Second Discussion List" <[email protected]> Sent: Tuesday, April 15, 2014 7:32 AM Subject: Re: [LEAPSECS] Earth speeding up? > I'm not a geophysicist, but I too have noted what Tom reports. I've attached > a plot that by coincidence I just made last week. > > The best hand-waiving arguments I've heard for these recent "decadal > fluctuations" > is that the oblateness of the Earth is changing, possibly due to the ice caps > changing. > Short-term fluctuations are much better understood, and they correlate very > strongly > with the atmospheric angular momentum. > > Demetrios, Thanks for sharing that one. Now, do you dare join the club and predict the year when we hit 86400.000? For a longer-term view, attached are two plots from a 2010 paper "Long-Periodical Variations of Earth Rotation, Determined from Reconstructed Millennial-Scale Glacial Sea Level" by Chapanov & Gambis translating mean sea level to excess LOD. See also the 2003 Nature paper "Sea-level fluctuations during the last glacial cycle" by Siddall & Rohling. One of these papers is from "New challenges for reference systems and numerical standards in astronomy" http://syrte.obspm.fr/jsr/journees2010/pdf/ Or I can email you copies. I have the raw data here somewhere too. /tvb
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