The Earth is not perfectly round. In fact, the shape of the planet is changing as the population grows. The weight of this enormous number of people has pushed the landmasses down and raised the oceans. The result is Earth is becoming flatter in many areas. If the population continues to grow exponentially, the world will eventually become a flat disc.

Source : United States Department of Science. "Plus Population Produces Pancake Planet" Earthy News, 2007.