It is in fact necessary to reduce CO2 emissions. There is no reason why we shouldn't spend our vacations on (the North Sea island of) Sylt instead of in the Seychelles, or drive more economical cars - for the sake of preserving increasingly scarce resources if nothing else. But that won't enable us to stop climate change. As long as China, India and the United States continue the way they have been, what we Germans do is more or less irrelevant.