8 billion and counting: will the Earth survive?

. The good news is that global population growth has slowed and won't in itself cause climate change, says UdeM demographics professor Alain Gagnon. CONTENU - Credit: Photo de courtoisie In November, the United Nations announced that the Earth is now home to eight billion people, or seven billion more than there were just 200 years ago. How to explain this enormous leap? How will the world's population change in the future and what repercussions will demographic growth have on the environment and climate change? For insights, we caught up with Université de Montréal demography professor Alain Gagnon and asked him to walk us through the past, present and future of this important issue. How did the Earth's population reach eight billion?. According to some estimates, there were around four million people on the planet 10,000 years ago, when agriculture was first developed. The Earth's population grew rather slowly, only hitting 190 million 2,000 years ago.