Cities generate most of the world’s economic activity, innovation, and cultural ferment. They also generate a growing share of its carbon emissions: according to the IPCC, cities are responsible for about 75 percent of global energy-related CO2 emissions. That number will only grow as the world continues to urbanize, especially in fast-growing nations like China and India.
Urban areas are also first in line to feel the effects of climate change. About 90 percent of urban areas in the world are coastal, so if nothing else, they will deal with sea level rise. Some 70 percent already report dealing with climate impacts. [...]
First, urban infrastructure has a huge influence on greenhouse gas emissions; “differences in the type and shape of the built environment can result in differences in urban transport and residential GHG emissions by a factor of ten.” [my emphasis] There is an enormous difference in emissions between low-carbon urban infrastructure — “relatively high-density households and population; mixed residential use, workplaces, retail, and leisure activities; a high number of intersections; and mobility choices that avoid excessive construction of low-connectivity roads” — and the high-carbon, sprawly kind.
Second, there is enormous inertia in urban infrastructure. “Among all long-lived capital stocks,” the researchers write, “land use, urban form, and road systems stand out for their century-long endurance, exceeding the lifetimes of coal power plants and car fleets.” Once these infrastructure decisions get made, they put in place “boundary conditions” that shape a city’s emissions trajectory for up to a century. [...]
C40 is a global group of 86 affiliated cities representing 650 million people and a quarter of the world’s GDP. While America was busy electing Trump, C40 was hosting a Mayors’ Summit in Mexico City. There, for the first time, a concrete roadmap was released showing how C40 cities could help meet global climate targets.
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