An enormous and ever-expanding quantitative data base now exists for the study of modern economic growth. The World Bank currently makes available a data archive for over two hundred countries since 1960 embracing a wide variety of economic and social indicators (World Bank, 2001). Working explicitly in Kuznets’ tradition, Angus Maddison (1995) has pieced together from the ever-growing data base time series on national product going back one to two centuries for 56 developed and less developed nations. Robert Summers and Alan Heston (1991) following the lead of Kuznets’ student, Irving B. Kravis, have developed data since 1950 for 152 countries on national product and its components carefully adjusted for international differences in purchasing power. Economic historians have compiled a variety of time series statistics for countries in Europe, Asia, and Latin America (., Mitchell 1975). To a large extent this immense body of data represents the fulfillment of Kuznets’ vision of a quantitative framework for the systematic study of economic growth. For most scholars in the field today — economic historians and economic theorists alike — these data both define the object of study and provide the testing ground for theory. Thus has the study of economic growth been redirected much as Kuznets advocated — a vision become reality.
Stephens' advice to developing countries is basically "become rich." That is happening in India and China (though growth in the latter country has slowed markedly over the last few years). But it is not happening in much of Africa, the Middle East, and central Asia. Climate disasters in such places will not appear very "expensive," because the countries are already so poor and likely to remain that way. But that is where by far the most death and suffering is going to happen. If places like the Democratic Republic of the Congo remain poor in 2100, how likely do we think it is that rich countries will pony up billions or trillions to rescue them from climate disaster — or accept tens of millions of climate refugees?