Thomas N. Gladwin (American, born 1948) is the Max McGraw Professor of Sustainable Enterprise and associate director of the Erb Institute for Global Sustainable Enterprise at the University of Michigan. His teaching, research, and consulting focus on system dynamics, global change, and sustainable business.
From now until 2040 the world’s urban population will grow from 3.5 to about five billion. The scale and speed of this urban growth will exceed anything witnessed before in human history. This increase of 1.5 billion will absorb virtually all of the world’s population growth during the time. Most of the growth in city dwelling will occur in what is currently called the developing world, principally in Asia and Africa. China and India alone will account for more than one-third of the total increase.Much of the growth will result from natural increases—higher birth than death rates—within existing cities. But a significant minority will come from rural to urban migration and urban area reclassification. The migrants will be motivated by both the pull of better employment opportunities and social services and the push of displacement caused by rural environmental and economic degradation.
While about 70% of the natural increase will occur in informal settlements (read: crowded slums), over 95% of the migrants from the countryside will begin their urban dwelling in these slums, typically situated in dangerous floodplains, river basins, steep slopes, or reclaimed land, and plagued by poor governance, inadequate infrastructure, and unhealthy living conditions. The number of urban slum dwellers in developing regions will grow from about one billion in 2010 to over 1.5 billion in 2030, given the economic inability or political unwillingness of urban governments to make slum alleviation a priority.
The urbanization process of the early twenty-first century will thus concentrate the bulk of world poverty into cities. About half of the growth will be situated in the world’s low-elevation coastal zones that possess less than 10% of global renewable freshwater supplies and suffer from severe ecosystem degradation. Following the persistent pattern of urban de-densification, the 2010–30 period will witness a huge increase in the spatial extent of urban built-up area, adding to the loss of farmland, forests, open space, and biodiversity.
But the big cities will also offer the best hope of escape. An estimated 0.5 billion people will shift out of slums into more secure living conditions during the next twenty years. The rapid urbanisation will generate substantial economic growth. It will foster economies of scale and agglomeration, face-to-face networks of creativity and collaboration, specialization, lowered transaction costs, and entrepreneurship, all generating huge productivity gains. With eighty million new people urbanizing each year, more than $35 trillion (35 T$!) will be spent between 2010 and 2030 on infrastructure including housing, transportation, sanitation, water, electricity, and telecommunications.
Trillions more will be spent on the expansion of services such as education and health care. Over one billion new jobs will be created. Rising per capita incomes will lift over two billion people into the global middle class, most significantly in Asia.
The period between 2030 and 2052 will witness more substantial global warming. By 2052, the planet will be on average 2°C warmer than in preindustrial times, with temperatures in central parts of the continents (Canada, United States, Siberia, China, the Amazon) even higher. This warming will radically alter urbanization patterns.
Climate-induced deglaciation, freshwater scarcity, drought, rain-fed crop failures, sea-level rise, tropical cyclones, forest fires, seasonal flooding, and extreme temperatures will cause massive population displacements, adding to the already substantial flow of migrants moving from rural to urban locations. Climate change will also motivate people to shift out of cities highly vulnerable to climate risks toward safer established or entirely new cities with more reliable precipitation, higher elevations, and cooler temperatures. Most of this human movement will initially occur within nations or regions where migration is permissible. Later there may be growing demands for long-distance migration toward more inhabitable regions such as northern Canada, Scotland, Scandinavia, and northern Russia—already called “the New North.”
Also between 2030 and 2052 well-governed cities in the wealthiest parts of the world (China, Brazil, United States, northern Europe) will increasingly invest in climate-change mitigation and adaptation. Greenhouse gas emissions will be reduced, particularly in the urban environments, via energy-efficient technologies, low-carbon energy sources, mass transit, promotion of nonmotorized transit, green building retrofits, mixed-use development, congestion charges, and other measures. These eco-cities will become super efficient through the application of pervasive computing, sensor networks, smart grids, and broad-based fiber-optic and wireless telecommunications.
Resource scarcities will be addressed through high-rise hydroponic farming, desalinization, bio-based building materials, massive waste recycling, and water-use/irrigation efficiency. Adaptations to climate
variability will include distributed infrastructure systems, construction of sea walls and storm-surge barriers, disaster-response capacities, and solar/wind-powered cooling and air-conditioning systems. Escalating energy, water, material, and housing costs will drive hundreds of millions of people from the suburbs and other nations into this safer and lower-cost urban living.
The 2030–52 climate-urbanization story will be very different for highly vulnerable cities with low adaptive capacities, most prominently in Africa and Southeast Asia. Still plagued by weak governance systems, corruption, insufficient international assistance, constrained investment capacity, political instability, infrastructure deficits, youth bulges, and massive poverty, cities in these regions will be unable to substantially reduce or adapt to the impacts of climate-related hazards.
Water supplies will be falling due to reduction in river flows, falling groundwater tables, and saltwater intrusion into groundwater. Heavy precipitation events will cause extensive flooding and landslides, leading to disruption of public water, electricity, sanitation, and transportation systems. Sea-level rise will increase coastal erosion and subsidence, causing substantial damage to residential and commercial structures. Temperature, precipitation, and humidity will boost the range, life cycle, and rate of transmission of infectious diseases. Higher temperatures and extended heat waves will greatly boost heat-related mortality.
Hundreds of millions from the countryside, where adverse effects of climate change will be even more horrific, will nonetheless be streaming into these climate-troubled cities. At the same time, employers, jobs, and wealthier residents will be fleeing these same cities in search of more secure places to live and to do business, often in newly developed cities or distant places. The adverse effects of climate change will thus fall disproportionately on those without the resources to move. Climate-vulnerable cities will be entrapped in a vicious cycle of increased harm, reduced adaptive capacity, and thus ever-greater vulnerability.
By 2052, our species will truly be Homo sapiens urbanis. The urban share of total global population will be approximately 80% (compared with 50% in 2010), with the currently industrialised countries at about 90% and less developed countries at 75%. These percentages exceed earlier projections, which failed to account for increased migration to the city because of erratic weather, resource scarcity, expensive commuting, and the general move from climate-vulnerable to climate-resilient cities.
The world will also be a very dangerous place, with the Global North spending trillions of dollars on security to prevent unwanted immigration and to guard against threats posed by criminal gangs and terrorists controlling cities increasingly afflicted by climate chaos in the Global South.