 Walter Greiling projected in the 1950s that world population would reach a peak of about nine billion, in the 21st century, and then stop growing after a readjustment of the Third World and a sanitation of the tropics.Estimates published in the 2000s tended to predict that the population of Earth would stop increasing around 2070;In a 2004 long-term prospective report, the United Nations Population Division projected the world population would peak at 9.22 billion in 2075.After reaching this maximum, it would decline slightly and then resume a slow increase, reaching a level of 8.97 billion by 2300, about the same as the projected 2050 figure.