Page - 15 - in options, Volume winter 2014/2015

15www.iiasa.ac.at winter 2014/2015 + options T he United Nations (UN) projects that the world population will grow to 11 billion by 2100. But that number may be off by two billion, according to new population projections developed by IIASA and the closely affiliated Wittgenstein  Centre for Global Human Capital. Their projections show that world population is likely to peak at 9.4  billion around 2070 and then decline to around 9 billion, with alternative scenarios that range from 7 billion to almost 13 billion. Why do IIASA’s projections differ from the UN’s? In part it is because of different data being used for fertility trends, which are the main drivers of long-term population growth. But the major difference lies in the explicit consideration of education and in the assembly of massive expert knowledge used to produce the new IIASA projections, which were published this fall in a new book, World Population and Human Capital in the 21st Century.  Quality quantity