[LEAPSECS] This year's Y2K: 'Leap second' threatens to breakthe Internet -Brooks

Tom Van Baak tvb at LeapSecond.com
Thu Jan 15 06:57:57 EST 2015

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).


----- Original Message ----- 
From: "Tom Van Baak" <tvb at LeapSecond.com>
To: "Leap Second Discussion List" <leapsecs at leapsecond.com>
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"

Or I can email you copies. I have the raw data here somewhere too.

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