Human populations and climate: Lessons from the past and future scenarios

The world population has undergone some periods of fast acceleration (the Late Palaeolithic and Neolithic revolutions, the demographic explosion started round year 1500); compared to these episodes, periods of decline appear of much smaller magnitude (except locally, of course). A variety of recovery mechanisms have existed to limit the consequences of mortality crises. Climate fluctuations, e.g., did not stop the growth of the world population. The United Nations expect a further growth of the population from 6.5 billions today to nine billions in 2050, and a possible stabilization round 10 billions by the end of the century. These projections do not take into account possible and unforeseeable catastrophes, which might also induce some new international migrations.