SciFi and Fantasy Book Club discussion

Help please, I am trying to find a book I read years ago. I can't remember the name of the book or the author! The premise of the book - and I think it is from the 80's - is that the magnetic poles have shifted on earth and the earth is a tilt. I know this isn't much to go on but I am hoping someone out there can give me a hint as to title and or author.

Clive Cussler has a thriller about that, if I remember rightly, but it's fairly recent, post 2000.