IPCC Fourth Assessment Report: Climate Change 2007

9.3.2 Socio-economic scenarios

The SRES scenarios adopt four storylines or ‘scenario families’ that describe how the world populations, economies and political structures may evolve over the next few decades (Nakićenović et al., 2000). The ‘A’ scenarios focus on economic growth, the ‘B’ scenarios on environmental protection, the ‘1’ scenarios assume more globalisation, and the ‘2’ scenarios assume more regionalisation. While some authors have criticised the population and economic details included in the SRES scenarios, the scenarios still provide a useful baseline for studying impacts related to greenhouse gas emissions (Tol et al., 2005). The situation for the already-vulnerable region of sub-Saharan Africa still appears bleak, even in the absence of climate change and variability. For example, 24 countries in sub-Saharan Africa are projected to be unable to meet several of the Millennium Development Goals (MDGs), and not one sub-Saharan country with a significant population is on track to meet the target with respect to child and maternal health (UNDP, 2005). The sub-Saharan share of the global total of those earning below US$1/day is also estimated to rise sharply from 24% today to 41% by 2015 (UNDP, 2005). It is within this context, coupled with the multiple stresses presented in Section 9.2.2, that the following summary of key future impacts and vulnerabilities associated with possible climate change and variability needs to be assessed.