The United Nations population division this summer released its 2012 population forecasts, predicting that there are likely to be 10.9 billion people in the world by 2100, up from 6.9 billion in 2010 (and about 7.2 billion now.) That figure is 1.8 billion more than the U.N.’s forecast of four years earlier. But Sanjeev Sanyal, the global strategist for Deutsche Bank, says the U.N. is underestimating how much fertility rates will decline, and says the 2100 figure is likely to be 8 billion, down from a 2055 peak of 8.9 billion.