View the article’s original source
Researchers from NASA and Stanford University recently estimated that the area directly affected by Beijing’s urbanization has quadrupled in size from 2000 to 2009. So while the area we call Beijing has remained roughly the same size, its environmental influence has grown far larger. These findings, published this week in the Journal of Geophysical Research: Atmospheres, draw on new computer models and data from NASA’s QuikScat satellite.
From 2000 to 2014, Beijing’s population grew from around 11 million to 21 million—today packing as many people into one city as there are in all of Australia (or North Korea or Syria). Strangely, the study didn’t measure the effect of more greenhouse gas emissions released by these additional residents and their vehicles. Instead, it only measured the growth of physical infrastructure—for instance, new roads and buildings.
The changes in the city’s physical infrastructure had massive, compounding effects on its weather and climate. New roads, for instance, reduce the ground’s albedo, its ability to reflect light and heat away from the city, and buildings prevented air from circulating freely. Those effects have resulted in higher temperatures and lower wind speeds. Researchers found that winter temperatures had increased in the city by 5 to 7 degrees Fahrenheit, while wind speeds were reduced by about 2 to 7 miles per hour, making the city air even more stagnant, according to the American Geophysical Union.
Some have argued that larger cities may be better for the environment in the long run because they use less land (and Beijing did not increase in land mass during this period) and there are economies of scale. Yet, this may primarily apply to (a) cities in the wealthiest countries and/or (b) cities with slower rates of growth. Simply adding ten million people in 14 years probably isn’t good for the environment as even the most advanced cities of today would have a difficult time absorbing that many people in housing, let alone dealing with the environmental impact. For a comparison, see the major infrastructure efforts in the Chicago region to mitigate flooding: the region has grown but this happened over a century and the Chicago region still has 10+ million fewer people than Beijing. And still it is very difficult to get a handle on stormwater and flooding during major storms, let alone in a city adding 10 million people in 14 years.