Researchers from Norway, Sweden, Japan, and the United States are pointing to the world’s big, affluent cities—with both huge carbon footprints, and the institutional capacity and infrastructure to shrink them rapidly—as the key to avoiding catastrophic global warming.

The scope of the study, recently published in the journal Environmental Research Letters, was vast and complex, Climate News Network reports. The researchers matched “all the information they could find about existing carbon footprints—estimates of energy consumption—with national statistics on spending patterns, regional purchasing power data, and a population map.” But its conclusion is straightforward and crystal clear: “When it comes to reducing fossil fuel use, carbon footprint, and emissions of greenhouse gases, mayors, governors, councils, and city bosses have as much opportunity as national governments—and more direct influence.”

“The top 100 highest footprint cities worldwide drive roughly 20% of the global carbon footprint,” noted co-author Daniel Moran of the Norwegian University of Science and Technology. “Concerted action by a small number of local mayors and governments can significantly reduce national carbon footprints.”

Climate News Net stresses the need for all urban jurisdictions, rich or poor, to take urgent action to dial down their own emissions—because even as cities are major drivers of climate change, “they are also concentrations of people who will be most at risk.”

But the new study places the burden of responsibility on the planet’s more fortunate urbanites—and, especially, on those who govern them. “Many of the world’s most carbon-intensive cities are in the world’s richest nations: that is, their civic authorities have the resources with which to act,” writes correspondent Tim Radford.

Among those resource-rich metropolises are Cologne, Manchester, and Montreal, all of which surprised the research team with their “unexpectedly large carbon footprints.” Those cities join other wealthy ones, like top polluters Seoul, Guangzhou, and New York, as jurisdictions where “targeted measures in a few places and by selected coalitions can have a large effect covering important consumption hotspots,” Moran told Radford.