What happened to the people who built the ruined temples of Angkor Wat, the long-abandoned statues of Easter Island, and the crumbling Maya pyramids of the Yucatan? In his new book Collapse: how societies choose to fail or succeed Jared Diamond suggests that the environmental crises which saw these civilisations collapse were self-induced. I have mixed feelings about Diamond’s generally optimistic concluding chapter. He uses the analogy of ‘the world as a polder’ to describe how we might choose to succeed. For Diamond, the Dutch ‘polder model’ is an example of how the co-existence of the man-made, and nature, has already been shown to work in practice. And he’s right: pervasive collaboration is essential if we are to secure a sustainable future. The reason I’m uneasy is that the polder model is right now under attack by the government now running the country; it presumably came to power after Diamond wrote his book.