Throughout the past year, countries around the world have announced individual commitments to cutting carbon dioxide emissions in hopes these cuts will keep global temperatures from rising more than 3.6°F (2°C) by 2100. With research showing the pledged emission cuts aren’t anywhere near enough to avoid dangerous climate change, experts say cities and other sub-national governments will be responsible for making up the difference.

The good news is that emissions from cities represent more than 70% of energy-related carbon dioxide emissions, and local leaders often have more autonomy to enact regulations—autonomy they are willing to exercise. Earlier this month, cities across the U.S. and China announced commitments to curtail their own emissions by a total of 1.2 gigatons of carbon dioxide annually. (For perspective, the entire U.S. emits between 5 and 6 gigatons each year.) And last week, states, provinces and other regions from Quebec to South Australia announced voluntary commitments to cut carbon emissions leading to a 7.9-gigaton reduction by 2030.

Cities have a capability to execute. Mayors are both powerful and grounded in reality.

“Cities have a capability to execute,” said Jules Kortenhorst, the CEO of the Rocky Mountain Institute, an energy think tank. “Mayors are both powerful and grounded in reality.”

Indeed, many climate and energy experts have turned to cities precisely because mayors can often take action in ways that national governments cannot. In the U.S. President Barack Obama has seen efforts to institute a cap-and-trade system thwarted and regulations on power plants challenged in court. But at the state level, California enacted a cap-and-trade system in 2006, cut greenhouse gas emissions and still managed to grow the economy.