The City and the Changing Climate

In the past, cities were safe havens for persecuted groups. Within the throng of a large city, one could, on some level, become anonymous, another speck of humanity coexisting alongside countless others. Cities also provided potential: jobs, education, and the hope of better living conditions.

Unfortunately, these urban areas became polluted and unsanitary, cutting the life expectations of people who were living inches away from open sewers. Once living conditions had deteriorated enough, though, city dwellers started a steady revolution to improve their cities. To take just one example, the Great Stink in London in the summer of 1858 was a major catalyst in the development of a brand new sewer system in that city.

The 20th century brought further improvements. Air and water quality were substantially improved in the U.S. after the introduction of the Clean Air and Water Acts under Republican President Nixon. Today, cities continue to progress rapidly: New York City’s success in cleaning up its waterways has had far-reaching implications. Up and down the eastern seaboard, for example, whale, dolphin and shark sightings have increased dramatically.

Cities present both an opportunity and a challenge when it comes to climate change. The heavy concentration of pollutants in cities stands in stark contrast to the wide dispersion in suburban and rural areas. However, the natural consolidation of human waste, both industrial and biological, allows engineers to centralize solutions. In this way, collection and disposal systems—of sewage, smog, and factory emissions, to name a few—can process and clean a large percentage of the population’s total waste stream. Recycling collection, much like garbage collection, can also be handled more efficiently and more profitably, giving private companies an upper hand in waste management.

Of course, there are still many issues that remain to be dealt with. Energy cycles present one challenge. The majority of the population follows a similar daily schedule: an active day followed by an inactive night. Energy is therefore used much more intensely during the day—and especially between lunchtime and early evening—than it is during the night. These natural cycles provide an opportunity for city planners to direct solutions at certain peak times of the day. Some of these solutions could be consumer-related through reduced per capita energy consumption, while others might target the source through increased energy storage during off-peak hours.

However, it would be naïve to say that if the world’s entire population lived in cities, greenhouse gases and other pollutants could be completely managed and controlled. After all, most cities import almost everything they need to function from surrounding areas, as well as from around the world; food, energy, and other goods are rarely produced in cities. And agriculture presents an especially challenging dilemma. As large consumers of resources—such as water and fertilizers—farms produce huge quantities of chemical and biological waste. The large surface area which agricultural regions occupy limits the effectiveness and efficiency of waste collection. Improved agricultural practices, therefore, are widely touted as the most effective means to reduce these pollutants.

Despite these limitations, city policies continue to cut down emissions for significant portions of the population, especially in the United States, where carbon emissions have declined by nearly 700 million tons in the past decade. A recent study by NASA on nitrogen dioxide concentrations across the US have further demonstrated cities’ improvements. Los Angeles decreased NO2 concentrations by 40% between 2005 and 2011. In the same period, New York City decreased concentrations by 32%, Atlanta by 42%, and Chicago by 43%. This success can be replicated around the world. China, most recently, has shown an environmental awakening that draws parallels to the US’s own 40 years ago. Cities will no doubt be the focus of emissions reductions programs in China as well over the next decade.