The emerging sub-field of world history is all about connections and interactions. It challenges the received treatments of history which have focused on specific regions and civilizations as if they had been discrete realities unto themselves, and reminds people that nothing happens in a vacuum. But to date world historians have not taken this approach far enough, since their work continues to focus almost exclusively on interactions and connections between humans. People should remind themselves that humans interact not only with each other, but in all times, places and contexts with the non-human world as well. All human actions take place within the context of ecosystems, and are affected by them in ways that differ enormously over time and space. In this paper, the author argues that the call for integrating environmental history with world history has an urgency beyond mere scholarly thoroughness. The theme of interactions, which lies at the heart of world history, offers a corrective to the fragmented approach of the knowledge system which has become dominant in the modern age. Fragmented thinking enables everyone falsely to perceive human activities as somehow disembedded from any physical context. So world history, if done properly--that is, expanding the theme of interactions to include all actors, not just human ones--is not only good scholarship, it may be vital to saving the planet! (Contains 51 notes.)