Cool! I had never before heard of this IITPW-theory. That could be just the gravitational anomaly I was looking for. Thanks!
About such a mechanism causing a mass extinction, I fear I got more than I bargained for. Shifting the climate bands like that, would kill of lots of plant life (for instance the Russian pinewoods and Congo basin both lying smack in the middle of desert bands,) release lots of carbon, basically resulting in a kind of "clathrate gun," similar to the PT-extinction. Flooding the atmosphere with such massive amounts of carbon, uses up the oxygen, killing even more life, making it possible for free methane to flood the atmosphere, resulting in a run-away greenhouse effect, killing of more life, releasing even more carbon.
Though I may have a safety net: Some of the tropical rainforests, especially the Amazon, are left in place. The carbon left by the clathrate gun actually stimulates plant growth, while the lack of oxygen takes away large herbivores and the danger of wild fires. So the jungles have a field day! Similarly the algeal blooms in the subpolar regions may regenerate quite quickly. So after an initial global suffocation follows a global oxygen injection, reducing the methane and returning everything back to normal.
Just two things:
1: I have no idea how long this mechanism would take to unfold.
2: I have no idea how severe it would be and how it would effect the human species and its domesticates.
(Scary thought: Isn't this clathrate gun exactly what is going on right now in the real world?)
By the way, you're saying this geography will bust up the thermohaline circulation. Could you elaborate that further?
I have a gut feeling you are right, you see, but I'm still unable to rationalize it.
I think I may be able to finish the continental shelves today, so I'll pbb post a new map this evening.