Today it takes the average citizen of Tanzania almost a year to produce the same volume of carbon emissions as is effortlessly generated every two and a half days by a European, or every twenty-eight hours by an American. We are, in short, able to live as we do because we use resources at hundreds of times the rate of most of the planet's other citizens. Once day - and don't expect it to be a distant day - many of those six billion or so less well-off people are bound to demand to have what we have, and to get it as effortlessly as we got it, and that will require more resources than this planet can easily, or even conceivably, yield. The greatest possible irony would be if in our endless quest to fill our lives with comfort and happiness we created a world that had neither.