This opinion piece which argues we have too many cities and thus are harming the ecology of the planet is just plain wrong. People in cities have a much smaller footprint in terms of impact on the planet per capita, than those who are not in cities.
This isn't intuitively obvious. People in a big city do have a great ecological impact.
The article, for example, notes that the Sears Tower uses as much electricity as a medium sized city. But, the Sears Tower also probably has as much, if not more, office space than a medium sized city and it probably uses far less energy to heat those offices and probably uses less energy to get the people in those offices to and from home.
In fact, people in cities eat up less open space, use less energy and pollute less in the process of transporting themselves to places they need to go, use less energy to heat the spaces they occupy, use less water to maintain lawns, and in general, have less ecological impact per person. This is why New York City is at the bottom and not the top of per capita energy use.
This planet may have a maximum carrying capacity for people. But, population growth levels off or ends without strong government intervention as countries grow more prosperous in any case. Mexico, for example, has seen its per woman fertility go from 6-7 kids per woman per lifetime, to just over the replacement rate, in just about a generation.
We do have to reduce human impact on the planet. But, trying to prevent urbanization in fundamentally a counterproductive way to address that problem.