Our world is very different than our grandparent’s. In 1950, there were about 2.5 billion people; today, there are more than 7 billion. Overall, people are healthier, wealthier, and more secure.

But this has come at a cost. The stress on our planet has been immense. Human beings have dramatically altered the climate, changed the chemistry of the oceans, and triggered mass extinctions. The impact has been so great as to define an entirely new geological era — the Anthropocene, turbo charged by a “great acceleration” of population, economic growth and natural resource consumption since the 1950s.