Unsustainable population growth

"In the last 200 years the population of our planet has grown exponentially, at a rate of 1.9% per year. If it continued at this rate, with the population doubling every 40 years, by 2600 we would all be standing literally shoulder to shoulder." said Professor Stephen Hawking as reported by Edward Morgan in Looking at the New Demography.

Morgan makes the case we are already in stage 5 of The Demographic Transition Model.