I have a column today in The Washington Post: “Why $11 a day represents extraordinary prosperity.” washingtonpost.com/opinions/… I summarize evidence of incredible growth in human prosperity over the last 30 years and how that prosperity has come, in fact, with slightly lower inequality at the world level and, since 2012, falling per capita carbon emissions. Hundreds of millions of families no longer live at the edge of subsistence. The point about carbon emissions is interesting: population growth has driven all the increase in total emissions since 2012. Since world population will peak around 2055, the path to decarbonization will be easier than often assumed. This is also why relying on what I think are the United Nations’ seriously flawed population projections is so damaging to good policy. If you feed the wrong population forecast into integrated assessment models of climate change, you will get the wrong policy implications. This is not about getting one Excel file wrong; this is about getting first-order decisions wrong. More pointedly, the experience of the last two centuries teaches us a clear lesson: good economic policy, based on the rule of law, markets, property rights, limited government, sound fiscal and monetary policy, international economic cooperation, and attention to families, education, health, and housing, can serve the common good: broad prosperity, lower inequality, technological dynamism, and stewardship of the earth. If we also find a way to fix the fertility crisis so couples can have the children they hope for, the possibilities for what we can achieve over the next 100 years are unbounded.