This sounds like urban legend. Such clouds consist mostly of ice crystals. Any hydrogen cyanide would be very tenuous if it were there, at the altitudes where such clouds occur. Should they somehow descend below the stratosphere, they would be diluted by the rest of earth's atmosphere.
Magnetic pole shift seems an unlikely candidate to explain for any of the observed phenomena. The direction of magnetic north has shifted some 10 degrees in New England since colonial times. There is no evidence either way that a flux change in our planet's molten interior is about to occur or not.
More likely it is due to repeal of don't ask don't tell, according to Cindy Jacobs:
Edited by maxwatt, 14 January 2011 - 05:37 PM.