Forming Alliances in the Fight Against Climate Change

May Boeve is always looking for converts. As executive director of the grassroots climate-change organization 350.org, Boeve spent the better part of 2014 reaching out to people and groups that, on the face of it, have priorities other than the warming of the planet. Glued to her phone for hour after hour, she persuaded labor unions, health organizations, and schools that they should prioritize climate change and that they should come to New York to demand action. Boeve’s tireless efforts contributed to the People’s Climate March in September, the largest climate demonstration in history, which organizers said drew some 400,000 people to New York. Thousands of others took to the streets in 161 other countries.

“What we do is try to mobilize these people to build a movement that’s greater than the sum of our parts,” she says. “No group can do this alone, no person can do this alone, so if we’re not actually building bridges, we will never achieve our goals.”

Boeve, 31, has been at the forefront of the fight against climate change since 2007, when she and six other undergraduates at Middlebury College in Vermont teamed up with environmentalist and author Bill McKibben to start 350.org. “All her powerful qualities were already evident, even at 20 or 21,” says McKibben. “She is mature way beyond her years.” 350.org gets its name from what some scientists say is the maximum level of carbon dioxide in the atmosphere to maintain a climate similar to the one we know today—350 parts per million (ppm). Currently, the Earth’s atmosphere is over 403 ppm, according to the National Oceanic and Atmospheric Administration. Boeve believes the only way to get that figure back to 350 ppm is to create a “massive social movement” to weaken the fossil fuel industry and usher in a broad embrace of renewable energy.

That’s a big task, which is why Boeve has become an expert at finding common ground with organizations that seem to have nothing to do with the environment. “Climate change connects every issue,” she says. “What I like to do is figure out, based on what another organization does, how does it connect to climate change and how does our work connect to what they do?” As part of her argument to labor unions, for example, she contends that environmentalism is good for the economy. Addressing climate change, she says, is a “huge opportunity to create jobs.”

“She is a person who is truly committed to making the compromises necessary to build the broadest-based movement possible,” says Jon Barton, senior strategic advisor on Climate and Energy for Blue-Green Alliance, a coalition of labor and environmental groups. “It’s not every day that people do that.”

Boeve has a new mission for her broad church of activists—getting the world’s biggest institutions to divest from companies directly involved in the fossil fuel industry. “You’re either on the right side of climate change, or the wrong side,” Boeve says. “And by actually forcing institutions to choose where they put their money, it forces us to make this into a moral issue.” So far Britain’s Guardian Media group, Syracuse University in New York, the Church of England and others have all committed to divesting from companies that extract, process or trade in fossil fuels.

Boeve knows that some of the climate damage is already done and can’t be reversed. “We don’t say we’re going to stop climate change. We can’t. It is with us already, it’s going to be with every generation to come,” she says. But taking on companies involved in the fossil fuel industry, she says, is a good start. “These folks are making money hand over fist making this problem worse,” Boeve says. “It’s very much a David and Goliath story.”

Write to Charlotte Alter at charlotte.alter@time.com.