“Let me add to the complexity of the situation we find ourselves in: At the same time we’re solving for climate change, we’re going to be building cities for 3 billion people,” said the urban designer Peter Calthorpe at the beginning of his talk at TED 2017. By 2050, he said, we will see the urban population double, and if we don’t manage to sustainably and practically build to accommodate that growth, “I’m not sure that all the climate solutions in the world will help save mankind,” Calthorpe said.

But there is a real enemy to target in this situation, Calthorpe said, and it is sprawl. When most people think of sprawl, they think of the low-lying scattering of buildings that circle metropolises and eventually fade into the suburban and the rural. But sprawl, Calthorpe said, can happen anywhere, at any density: Its key attribute is that it isolates people.

Separating people into economic enclaves and land-use enclaves, dividing them from nature, and prioritizing vehicle transportation (all key features of sprawl) doesn’t allow for the kind of close-knit, communicative growth that allows cities to develop in a way that hinders, not hastens, climate change.

Calthorpe’s software and urban modeling company, Calthorpe Analytics, has developed a tool called UrbanFootprint that gives planners and developers a way to test out the impact of future development models. For the state of California, Calthorpe Analytics used UrbanFootprint mapped out two different scenarios for 2050–one in which the state continued its “business as usual” sprawl-driven development and one in which it shifted to compact development, prioritizing dense housing and mixed-use streets.

Read the full article on climate and urban sprawl by Eillie Anzilotti at FastCompany