Moments after Donald Trump announced that the United States would withdraw from the Paris climate accord — President Obama's landmark legislation aimed at reducing global pollution — Bill Peduto, Pittsburgh's mayor, shot back a defiant Tweet.

"I can assure you that we will follow the guidelines of the Paris Agreement for our people, our economy and future," the two-term mayor promised, responding to the President's nonsensical quip that he "was elected by the voters of Pittsburgh, not Paris" (to clarify, Pittsburgh voted overwhelmingly for Hillary Clinton in the 2016 election).

And Peduto wasn't alone. In the wake of the worldwide outrage at Trump's indifference to the climate catastrophes already ravaging the planet, politicians from Los Angeles to Atlanta and Salt Lake City came together to reaffirm their commitment to the renewable energy targets set by the previous administration.

Author and environmentalist Bill McKibben has been agitating against the coal, oil, and gas industries since well before the current White House turned away from climate scientists' grave predictions. His 1989 study, The End Of Nature, resonates as a prescient warning against the disastrous effects of human technologies on the Earth, and his organization, 350.org, advocates for a 100% clean energy initiative spanning 188 countries worldwide.

Despite Trump's surprising victory last year, McKibben isn't giving up on the fight to protect our planet from looming environmental cataclysm — though with a Republican-controlled Congress, he has his work cut out.

"Individuals need to join together," McKibben urges. "That's why there are groups like 350.org that are working hard all over the world to sever the finances of the fossil fuel industry, for fracking wells and oil exports. We need to divest from fossil fuel stocks, go after the banks that loan to new fossil fuel businesses, and convince cities and states to move towards renewable energy." If McKibben's call to action feels daunting, he's quick to point to the unfazed regions across the country where it's already working, noting cities from San Diego to Boulder and East Hampton that have pledged 100% clean energy targets for the coming decades.

While McKibben thinks that the math of climate change is no longer amenable to individual efforts, like recycling or conserving your water use, he's still hopeful that grassroots activism could spur widespread change on the state level. For example: Writing a letter to your newspaper's editor, holding small businesses accountable, supporting candidates who prioritize climate science, or even running for office yourself are just a few of the ways to get involved. And by working to make your local community a leader in environmentalism, we may be able to move the carbon needle, even from under the Trump administration.

Watch America Uprising: Climate Change above to learn more about McKibben's efforts to keep this vital cause alive in the era of Trump.