I recently read a blog entry from a leap-second expert explaining that in near term (i.e. last 3 years) the Earth has been spinning ever so slightly faster, delaying the need to insert a leap-second (that accounts for the Earth spinning at a different speed than once per 24 * 60 * 60 seconds).
That got me wondering what effect Climate Change might have had on the spin of the Earth over the last century, and into the next.
I reasoned that melting ice caps would bring mass closer to the centre, lowering the moment of inertia and speeding up the spin (which was a silly thought - see comments).
But then I reasoned that warming oceans would lower the density of water, pushing the mass away.
Then I realised I had no idea what effect of the changing atmosphere might have.
I came away knowing I had a very poor understanding of the problem.
What predictions do the scientific models make about the effect of climate change on the previous rate of gradual slowing of the Earth's spin?
[Note: This is an idle curiosity question from a non-expert. Please tailor your answering efforts appropriately.]