Across the world, cities have become epicenters of action to stop climate change — and some of their most energized, effective leaders are women mayors.

Cities lie at the center of the global warming crisis because they are both major sources of the problem — they generate 70 percent of greenhouse-gas emissions — and founts of solutions, offering rich opportunities for efficiency and keen communities of innovators. Many cities are rushing to marshal local resources, add low-impact rapid-transit and bicycle lanes, and incentivize green building. City governments may not sign global climate accords, but they are vital to implementing agreements and realizing a greener future.

Many of the people standing up to make that change are women, who are often on the frontlines of climate-related crises. Women are among society’s most vulnerable and least powerful, especially in poor countries, so suffer more from environmental disasters and extreme weather events. And they are often their families’ first responders to health emergencies caused by pollution, such as asthma or contaminated water.

As a result, women are more likely to be concerned about environmental issues and climate change. And, when they do reach positions of power, they are more likely to work to do something about it. Among those women are the 15 women mayors who have joined hands through C40, a network of world megacities committed to addressing climate change.

In this series, Women Talk Climate, we interview four of these mayors from four different continents. One of them is Cape Town Mayor Patricia de Lille, who said at the C40 Women4Climate conference in New York in March that it’s her job to “empower other women so they can survive the impact of climate change.”

One innovative way she’s doing that is by turning land plagued by illegal dumping into community gardens that both help green the city and improve food security. The program’s success in local communities made plain the fact that “women are natural leaders,” she said. “We know we are in charge.”

When it comes to addressing climate challenges — which so often are intertwined with poverty, public health and other urban problems — including women is a matter of efficiency, not political correctness. It’s the path to aiding the most vulnerable, supporting first responders and improving our chances of identifying the best solutions and most effective response.

This project explores the challenges facing four very different world cities — Paris, Cape Town, Washington, D.C., and Sydney — and the necessarily different local responses being pursued by their women mayors. As you will see, all four mayors are proving that women are not only effective implementers, but also innovative strategists, tough power-brokers and game-changers doubling down in the fight to save the planet.