Continental physiography, climate and the global distribution of human population

Joel E. Cohen, Rockefeller University and Columbia University
Christopher Small, Columbia University

Geographically indexed moderate-resolution demographic and geophysical data are combined to quantify the spatial relationships between population and basic geophysical parameters of continental physiography and climate. We describe the localization of human population with respect to elevation, coastal proximity, regional temperature and precipitation. A global compilation of census data specifies the population distribution to a median spatial resolution of 31 km. Local population densities span more than six orders of magnitude. 50% of the global population occupies less than 3% of Earth’s habitable land area. Average population densities are 3-4 times higher at low elevations and near coasts than inland; 38 percent of the 1990 population lived within 100 km of a sea coast. Inland population densities are highest in topographic basins where conditions are suitable for agriculture. Population distribution is more uniform with respect to climatic parameters. Average population density increases significantly in regions with high seasonal variability in precipitation.