Can we still ‘afford’ wilderness? And if so, should we aim to use it ‘sustainably’? The straight answers are: yes, and no. But the terminology is misleading. The total cash cost to buy all the world’s remaining areas of high biological diversity at cur-rent local land prices is estimated at $20 billion per year for ten years. This is less than annual US expenditure on soft drinks. So yes, the world can afford it. We rely on relatively undisturbed natural ecosystems to clean the dirty air and water which emanate endlessly from our cities. Wilderness areas, especially oceans and tropical grasslands and forests, also absorb atmospheric carbon to mitigate human-induced climate change.