This map shows global population dynamics over two scales. The first indicates national rates of migration from rural areas to cities from 1990 projected to 2050. The second, indicated by circles represents the population size of individual cities and their rate of growth from 1990 projected to 2030. Essentially, this map shows the global phenomenon of migration to cities and registers the intensity of that migration.
In 2015 the global population was circa 7.3 billion people. The United Nations forecasts that this will grow to 8.5 billion by 2030, 9.7 billion by 2050, and anywhere up to 13.3 billion by 2100. 1
With the need to source energy, food, water, and housing for so many additional people this century is likely to see competition for resources between people and between species take place on a scale not previously experienced. On the contrary, as pressure increases in the developing world, much of Europe is now experiencing shrinking population. 2 Whether these nations can or should help relieve pressure in other parts of the world by opening their borders or boosting their immigration quotas is vexed.
The UN reports that there is a 23% chance that global population will stabilize or fall before 2100. This would bring to an end a growth cycle which began when a global population of circa four million nomads started to transition into settlements with the birth of the agricultural revolution.
1 United Nations, Department of Economic and Social Affairs, Population Division, World Population Prospects: The 2015 Revision, Key Findings and Advance Tables (2015). Available at https://esa.un.org/unpd/wpp/Publications/.
1. Rural Population Change
United Nations, Department of Economic and Social Affairs, Population Division (2014), "World Urbanization Prospects: The 2014 revision" Rural Growth Rate, https://esa.un.org/unpd/wup/CD-ROM/Default.aspx (accessed November 14, 2014).
2. Urban Population
Esri, DeLorme Publishing Company, Inc. "World Cities" (2011), http://www.arcgis.com/home/item.html?id=dfab3b294ab24961899b2a98e9e8cd3d (accessed November 20, 2014)
3. Urban Population Change
United Nations, Department of Economic and Social Affairs, Population Division (2014), "World Urbanization Prospects: The 2014 revision" Urban Growth Rate, https://esa.un.org/unpd/wup/CD-ROM/Default.aspx (accessed November 14, 2014).
Critical Ecosystem Partnership Fund, "The Biodiversity Hotspots," http://www.cepf.net/resources/hotspots/pages/default.aspx (accessed July 1, 2014). Data made available under the Creative Commons BY-SA 4.0 License: https://creativecommons.org/licenses/by-sa/4.0/legalcode.