- We see evidence that lakes and forests and wetlands can have different equilibria — so you have a savanna system that may be stable and thriving, but it can also tip over and become an arid steppe if pushed too far by warming, land degradation and biodiversity loss. A clear-water lake can become a murky, biodiversity-low anoxic lake. Unfortunately, the science is increasingly showing that even large systems can tip.
- Interview by Mary Hoff in Momentum magazine (Winter 2012).
- We are on average, moving towards four degrees warming this century. And we haven’t been in a four-degree warmer world for the past four million years. So it’s not as if it’s a place we know very well.
- Interview in the documentary-film Before the Flood by Fisher Stevens (2016).
- Meat plays a disproportionately large role in causing this overuse of freshwater. Twenty-five percent of the rivers in the world no longer reach the ocean, because we're taking out so much water to produce animal feed. … Agriculture is not only the biggest culprit threatening the future for humanity on Earth, it is also the biggest and most important silver bullet to a solution.
- Interview in the documentary-film The Game Changers by Louie Psihoyos (2018).