Earth has become an urban planet.
Cities are growing everywhere.
More than half of the world’s people
already live in cities.
By 2050, 2 out of 3 of us will live in a city.
That has sobering implications for the environment.
Cities consume vast amounts of
food, energy, and materials.
This “ecological footprint” can extend
far beyond the city’s edge.
Indeed, the land area needed to support a city
can be 200 times bigger than the area of the city itself.
Another challenge is that cities are expanding into areas
rich in biodiversity.
That’s because we like to live in the same places
that are favored by plants and animals.
Cities alter the environment in dramatic ways.
Tons of concrete store heat...
City centers become “heat islands” that are
warmer at night and hotter by day.
Urban are noisy… and artificial light means
it never gets really dark.
Paved roads and rooftops prevent water
from soaking into the soil.
That leads to flash floods and lots of polluted runoff
that can harms streams and rivers.
But an urban planet is not all gloom and doom.
When you put a lot of people in one place,
you can improve efficiency.
City dwellers can use a lot less energy, per person,
than people living in rural areas.
Doing it right will require smart planning.
And one thing is clear:
Cities are here to stay, and the decisions we make today
about how we build and live in them
will shape generations to come.