Hmmm...something on the order of a second per year might be caused by our solar system passing through a denser part of space....say like some thicker hydrogen clouds. Whether that extra amount of friction would make a difference of a second a year is anybody's guess.
They do say that there are signs that the poles of Earth's magnetic field are getting ready to flip again, and that just before that happens there will be a temporary decrease in the strength of our magnetic field. Again, it's hard to say what the result of that will be on the length of a year, but that will definitely be a bad century for laying in the sun.
