More than half of the world’s people live in urban areas, and this number continues to grow. Some scholars think that, by 2100, almost all people will live in cities because the benefits from efficiency and productivity outweigh the costs associated with any negatives of city life. Other scholars think that increased urbanization is unsustainable due to the high levels of material consumption and waste production that result from large populations co-existing in a relatively confined area.
Big cities have many social problems, such as congestion, crime, inequality, and unemployment, but they are even more significantly threatened by climate change. Our ceaseless burning of fossil fuels fills the atmosphere with carbon dioxide, leading to global warming and to more severe, not to mention less predictable, weather patterns. Paved surfaces preventing evaporation and the heat storage capacity of large buildings means that cities create their own micro-climates resulting in much higher temperatures, and lower rates of cooling, than are found in the surrounding areas. These urban ovens are basically baking themselves into extinction.
In a recent article in Futures (2015, 66: 45-53), on the future of cities in a warming world, Patrick Moriarty and Damon Honnery identify three areas of concern: health, flooding, and geological.
Large cities already suffer from increased air pollution that can cause or exacerbate a variety of pulmonary disorders. As temperatures rise, the potential for heat stroke, especially among the elderly, increases dramatically. Warmer cities outside of tropical areas may see a rise in the number of cases of tropical diseases, such as malaria.
Most of the world’s major cities are on sea coasts or the banks of major rivers. The increase in severe weather events has exposed these areas to threat from storm surge. Even a small rise in water levels as a result of polar ice melting is likely to leave some of the heaviest populated urban centers in the Mediterranean and South Asia partially submerged only a couple of decades from now.
Research has shown that global warming can even have an impact on major geological events, like volcanoes and earthquakes. In mountainous regions, destabilization of the terrain is leading to more rock slides and mud slides that can quickly bury a city and cut off access to help from outside.
When the impact of climate change is taken into account, a more realistic forecast for urban development can be constructed, with Moriarty and Honnery suggesting that we will reach a stage of peak urbanism within a few decades. Some existing cities will no longer be habitable. New, more sustainable (less densely populated) cities, specifically designed to co-exist with the environment, may arise in previously less hospitable areas. There might also be a resurgence of rural living, as large portions of the population seek an alternate lifestyle.