African poverty: a grand challenge for sustainability science.

W hen we began to put together this special feature on poverty and sustainability science, we sought significant science-based research and perspectives on poverty worldwide. However, the six articles that have emerged from a lengthy solicitation, preparation, and review process, with one exception, all focus on sub-Saharan Africa. The exception, the absolute poverty measures for the developing world by Chen and Ravallion (1), serve to provide the latest evidence for an African exceptionalism that dominates the development needs of today. Briefly stated, all developing country regions have shown marked improvement in key indicators of poverty, health, economy, and food, except for sub-Saharan Africa. For poverty, the global number of people living below the extreme poverty line of $1 per day decreased between 1981 and 2004 from 1,470 million to 969 million. The percentage of extremely poor fell from 40% to 18%. However, in sub-Saharan Africa, the numbers almost doubled from 168 million to 298 million, and the percentage stayed almost constant from 42% to 41% (1). For health, the life expectancy at birth in sub-Saharan Africa peaked in 1990 at 50 years but has since declined to 46 years, while steadily rising in all developing country regions to an average of 65 years (2). Over the period 1960–2000, sub-Saharan Africa’s per capita measure of annual economic growth (gross domestic product) was a mere 0.1%, whereas other developing country regions experienced accelerated growth averaging 3.6% (3). Food production per capita grew by 2.3% per year between 1980 and 2000 in Asia, grew by 0.9% in Latin America, and declined by 0.01% in tropical Africa (4). Understanding African exceptionalism and contributing to its reduction is one of the grand challenges of sustainability science. In this brief introduction, we have characterized the ways in which scientists can contribute to meeting the challenges as describing poverty, understanding causation, and offering and evaluating policies and solutions.