Cities can play a major role in the global effort to curb climate change, a new report says—and a major step they can take is helping their inhabitants consume a whole lot less stuff by making changes in the way cities are run.

Even the most forward-thinking cities have a long way to go to neutralize their carbon emissions, the report says. That’s partly because for years, cities have been doing carbon math wrong, adding up only the carbon costs that occur within city limits. But much of city dwellers' climate impact actually comes from the things they eat, use, or buy that originate far outside the city—from food to clothes to electronics and more.

To keep emissions in check, the report