Development paths of drylands: thresholds and sustainability

Drylands (41 and 35% of global land and population, respectively) have the lowest biological productivity of any ecosystem, contain populations with the highest growth rates on earth, and share a significant fraction of global poverty for which desertification is implicated. A global assessment of the available information indicates that the inherent low productivity of drylands, when combined with other adverse factors, can generate poverty. It additionally indicates that while the drylands may exist in a locally stable and sustainable state, this is readily destabilized by non-linear, threshold-crossing transitions to an alternative steady-state leading to desertification, poverty and conflicts. The desertification paradigm'' (human and climatological pressures driving overexploitation of land resources, leading to desertification, poverty and reduced security) is challenged by its counter-paradigm'' (adversity elicits innovation, leading to ingenuous solutions for avoiding desertification). But the latter does not account for the inevitability of continued and increasing pressure on the finite dryland resources, expected to be further exacerbated by a globally increasing need for agricultural land. A companion paper points out that this situation can be avoided by reducing dependence on land productivity, through adoption of alternative livelihoods.'' These livelihoods, while economically advantageous, reduce pressure on land resources.