[D]espite these costs, the major governments throughout the world still morally ought to take some of these steps. The clearest moral obligation falls on the United States. The United States caused and continues to cause more of the problem than any other country. The United States can spend more resources on a solution without sacriﬁcing basic necessities. This country has the scientific expertise to solve technical problems. Other countries follow its lead (sometimes!). So the United States has a special moral obligation to help mitigate and adapt to global warming.