Everybody knows about the spread of war, the rise of AIDS and other diseases, the hopeless intractability of poverty. One survey found that two-thirds of Americans believed that the proportion of the world population living in extreme poverty has almost doubled over the last 20 years. Another 29 percent believed that the proportion had remained roughly the same. That's 95 percent of Americans - who are utterly wrong. In fact, the proportion of the world's population living in extreme poverty hasn't doubled or remained the same. It has fallen by more than half, from 35 percent in 1993 to 14 percent in 2011 (the most recent year for which figures are available from the World Bank). The world's best-kept secret is that we live at a historic inflection point when extreme poverty is retreating. United Nations members have just adopted 17 new Global Goals, of which the centerpiece is the elimination of extreme poverty by 2030. Their goals are historic. There will still be poor people, of course, but very few who are too poor to eat or to send children to school. Inequality [remains] a huge challenge in the U.S. But globally, inequality is diminishing, because of the rise of poor countries. The challenge now is to ensure that rich donor nations are generous in supporting the Global Goals - but also that developing countries do their part, rather than succumbing to corruption and inefficiency. So let's get down to work and, on our watch, defeat extreme poverty worldwide. We know that the challenges are surmountable - because we've already turned the tide of history.