Global Alternative Long-Term Urbanization Projections

Leiwen Jiang, National Center for Atmospheric Research (NCAR)

Projections of urban growth are critical to assessment of many socioeconomic and environmental issues. Global change studies in particular require consistent sets of projections to cover sufficiently long time horizons and span a wide enough range of uncertainty. Existing projections do not meet these needs. Here we present a new, global set of urbanization projections that describe fast, central and slow urbanization pathways for all countries over the 21st century. Derived based on historical urbanization experiences over the 1950-2010 period, the projections cover a wide but plausible range of outcomes and are further tested by deriving implied rural-urban migration flows in selected countries. Results show a wide range of plausible urbanization outcomes varies much more widely than indicated by available projections, and indicate that by the end of the century urbanization levels across regions could either converge under the Fast scenario or remain diverse under the Slow scenario.