For almost thirty years, the international effort to bring climate change under control has appealed ultimately to moral motives. We have been told we should make the small sacrifice of reducing our emissions of greenhouse gas for the sake of the much greater benefit it will bring to other people. In particular, the current generation should reduce its emissions for the sake of the future. But action against climate change must principally come from governments, and not all governments are susceptible to moral motivation. For this reason the effort is failing. We must try a different approach. Because greenhouse gas is what economists call an 'externality', it is possible in principle to respond to climate change in a way that is in everybody's interest. The great benefit that will result from controlling climate change can in principle be distributed across people and generations in such a way that no sacrifice is required from anyone. If this can be achieved in practice, we can harness the powerful motivation of self-interest to control climate change. But to make it possible in practice, we need a new economic institution, which might be called the World Climate Bank. International effort should be redirected towards creating this institution.