Grist: Its helpful to understand game theory if you want to know why its so difficult to reach an international deal to reduce climate emissions. Everyone will be better off if everyone does their part, but if one country gets away with doing nothing while the others reduce their emissions, that country would be the biggest winner of all, enjoying the benefits of averted catastrophe without any of the costs. That calculation could lead to a lot of countries bailing out. No one wants to be the sucker who...