As you put it in your leader on how best to cut carbon-dioxide emissions, “international agreements are helpful only in so far as they encourage individual countries to control their own emissions” (“Bad Policy Will Boil the Planet,” October 17, 2009). Assuming that domestic policies are up to scratch, everything ultimately depends on how governments will implement them. International agreements are useful in several ways you do not mention, though. Most important, they can focus attention on countries whose emissions are most troubling for the planet: America from burning oil, China from burning coal, Brazil from deforestation, and so on. In addition, they can focus attention on domestic policies that are most likely to lead to desired results. Your article about energy and climate change in Britain clearly shows that markets are not up to scratch in this regard (“Questioning the Invisible Hand”). But the last paragraph of this article points out yet another useful rôle for international agreements: shaming of laggards in domestic policies controlling carbon emissions or in their implementation. Perhaps this is the best we can expect from the December meeting on climate change in Copenhagen. And shaming is a potent tool, no doubt.