What Kristof doesn't state, however, are these facts:
1. Those people live almost entirely in China and India.
2. The rise in nominal wealth has come from a tremendous increase in energy consumption.
3. Both nations have extreme environmental problems, including the worst air pollution situations in the world, result of extreme amounts of coal consumption, water shortages, water pollution, and extensive land contamination from mining, industrial, municipal, and other waste.
4. Though overall efficiency in GDP output per unit energy has increased modestly, overall, increases in economic wealth require vast amounts of additional resource consumption.
The combination of factors 3 and 4 above means that the gains in economic output are being accomplished largely by both strip-mining resources and exhausting effluent dumps in China and India.
5. Much of the apparent "de-materialisation" of economies in the developed world outside China and India is actually, on closer examination, based on exporting raw material (and effluent) demands to those countries. See research out of CSIRO (Australia) and UCSB.
6. Outside of China and India (though yes, they're both huge countries), progress in the "developing" world has been far more modest. In cases, backsliding. Add to this economic regression through much of the Middle East and North Africa (much of the disturbances of the Arab Spring is attributable to economic circumstances), and even in OECD/European nations, particularly Greece, Italy, Spain, and Portugal.
And finally: the foundations of modern economic wealth, vast quantities of nonrenewable resources, tapped at uttelry unsustainable rates, are quite simply not sustainable. Without looking to this basis, effectively the fuel in the tank, observations of altitude or velocity tell little.