A type of forcing caused by plate-tectonic-movement-driven changes in the global location of land masses.
Several times in Earth's history all of the continental plates have been locked together in one area of the globe. For example, Pangea was a super-continent that existed 250 million years ago. It was surrounded by a the vast expanse of water that the people at the time called Panthalassa (just kidding).
1. Epeirogeny affects climate because continental land mass arrangement influences ocean circulation, and since ocean circulation is what performs the heat transport that regulates the global climate, wandering land masses can cause climate change.