What If the Earth Were Rotated 90°?

In the What If? video series, Randall Munroe of XKCD and Henry Reich of MinutePhysics look into wild theoretical questions, no matter how stupid they are. Now, we know that the earth rotates 360° every day. But this question is about rotating it in a different direction, changing its orientation completely. To see what would happen, they theoretically made the Greenwich Meridian into the equator. That changes everything, especially the way we see the globe. London is suddenly in the tropics, and India is where Siberia used to be. If this change were to happen gradually, the earth would adapt, but it it were sudden, it could be a extinction event.