A historical perspective can shed light on the dilemmas and dimensions of current ecological predicaments. Consideration of long-term trends in economic, demographic, and energy history show just how peculiar, disruptive, liberating, and unsustainable modern times have been. The current era of ecological tumult derives its impetus from many sources, not least the near-stasis in ideas and politics. It is the big ideas, like nationalism, communism, or the premium placed on economic growth, rather than explicitly environmental ideas, that most affected environmental (...) policy and outcomes in the 20th century, and will likely continue to do so in the 21st. (shrink)