"We’re facing some questions in this century that are existential in their nature. One is, have we inadvertently pushed so many other fellow species off this planet, species that we coevolved with, that we depend upon for our food and for all kinds of other things that they do, filtering the air, filtering the water? Have we pushed so many of them off that we have started a cascade that is ultimately leading to a that’s going to include ourselves? Second, the climate. We have lived in balance through most of the history of our species with this very thin layer of air that surrounds the planet. But then we jet-propelled our society because we discovered how to tap the energy that nature didn’t need for its own cycle, the excess carbon it had buried away. We’ve dug it all up, and we’ve burned it, and we’ve created these marvels, including the internet that you and I are speaking to each other with right now. In the process, however, we packed the atmosphere with some invisible gases that [hold heat]. We’re basically baking ourselves right now because we have created the . Are we going to be able to stop that process in time? We’re exceeding limits that scientists have warned us we should learn to live within."