More than 300,000 people marched in New York City for the People’s Climate March on Sunday, calling for aggressive action on global climate change as world leaders meet for the United Nations’ Climate Summit this week.

"We can still avert catastrophic change if we act quickly to reinvent our economy and our relationship to the Earth," Jessica Hellmann, a conservation biology professor at Notre Dame and climate change expert, told NPR. “But we must also find ways to live with the climate change that has already started. Corporations and the development community are already helping the world to adapt, but these efforts are not enough.”

While New York City’s march was the largest climate-focused mobilization effort ever—far outnumbering the 100,000 initially expected to attend—it’s unclear what will ultimately come of it. Two of the world’s largest countries and greenhouse gas emitters, India and China, weren’t expected to attend the U.N. summit and past attempts at unifying world leaders around climate change have faltered.

That said, the strong show of U.S. support for climate change action does signal something important for U.S. business leaders: Americans are becoming more interested and aware of the long-term dangers of climate change. Companies large and small can no longer ignore climate change as an issue. Here are three ways small businesses can make a difference and show their support.

1. Take a stance. It’s no longer taboo to talk about climate change in the business world, and several large U.S. corporations including Pepsi and McDonalds have already taken a lead. Walmart—which has greatly emphasized environmental sustainability throughout its massive worldwide operations—now regularly discusses the risks of climate change and the business case for focusing on environmental sustainability. “It’s not something that we’re doing for public relations or it is the nice thing to do,” Walmart vice president Manuel Gómez Peña said earlier this year. “It’s now making business sense.”

2 Walk the talk. Consumers want to see companies do more than just talk about sustainability. More than ever, they’re looking beneath the surface for true action. Every company, regardless of its size, can find ways to become more sustainable. Technology startups can focus on making their products and offices more energy-efficient; retailers can focus on selling sustainable, locally made products, improving energy efficiency in their stores and encouraging their customers to use reusable shopping bags. (Want to know where to start? Check out this list of 11 ways companies can reduce their environmental footprint.)

3. Think differently, and long term. Ultimately, climate change, and the actions required to truly fight it, will require many business leaders to change the way they approach their business. Some small businesses are already taking a leap—focusing on new business models (like the sharing economy) that encourage sustainable consumption among customers. Others are investing in technologies like renewable energy systems—though may take several years to pay for themselves—will dramatically reduce their long-term environmental impact. (Check out this Salt Lake City small business, Publik Coffee Roasters, that recently finished a sustainable renovation including solar panels.)

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