Birthrates are falling but not fast enough
What constitutes an optimal human population?
Assuming more or less contemporary aspirations and technological capabilities, highly efficient energy systems and resource use, and closing of the rich-poor gap, we came up with a figure of around 2 billion people – the number of people that were alive in the 1930s.
“The more people there are, the more climate change humanity will face”
(Paul and Anne Ehrlich, “Enough Already” “Where the babies are”, New Scientist, Vol 2571, 30 September 2006, p48)