A later follow up, this from the current issue of Nature magazine:

The end of world population growth

WOLFGANG LUTZ*, WARREN SANDERSON*† & SERGEI SCHERBOV‡

* International Institute for Applied Systems Analysis, Schlossplatz 1, A-2361 Laxenburg, Austria
† Departments of Economics and History, State University of New York at Stony Brook, New York 11794-4384, USA
‡ University of Groningen, PO Box 800, NL-9700 AV Groningen, The Netherlands

Correspondence and requests for materials should be addressed to W.L. (e-mail: lutz@iiasa.ac.at).

There has been enormous concern about the consequences of human population growth for the environment and for social and economic development. But this growth is likely to come to an end in the foreseeable future. Improving on earlier methods of probabilistic forecasting, here we show that there is around an 85 per cent chance that the world's population will stop growing before the end of the century. There is a 60 per cent probability that the world's population will not exceed 10 billion people before 2100, and around a 15 per cent probability that the world's population at the end of the century will be lower than it is today. For different regions, the date and size of the peak population will vary considerably.