An uncertain future means a range of plausible outcomes. Unlike previous research, including our own (for example, Nelson et al. 2009), which relied
on a single baseline scenario of GDP and population, this research uses three
combinations of income and population growth: a baseline scenario that is “middle of the road”; a pessimistic scenario that, while plausible, is likely to result in more negative outcomes for human well-being; and an optimistic scenario that would result in more positive outcomes. Another advance is that each of these three overall scenarios are subjected to four plausible climate futures that range from slightly to substantially wetter and hotter on average than the current climate. We then compare these four climate futures with
a fifth scenario, of perfect climate mitigation—that is, a continuation of today’s climate into the future. Three overall scenarios, under five climate
scenarios, result in 15 perspectives on the future that encompass a wide range of plausible outcomes. Using the baseline scenario, we experiment with a variety of crop productivity enhancement simulations. Finally, we present the results of a simulation of an extended drought in South Asia—one likely outcome of climate change—to give some perspective on the effects of increased climate variability for one part of the world.