Across the U.S., people protested outside major banks on Tuesday, calling on financial institutions to shift investments away from fossil fuel companies. In Boston, more than 200 people marched from a Chase Bank to a Bank of America branch. A man there used a solar-powered chain saw to cut through giant credit cards from Chase and Bank of America.

One hundred protests took place across the country, from Juneau, Alaska, to Washington, D.C., to urge banks including JPMorgan Chase, Bank of America and Citi to stop funding fossil fuel projects, which significantly contribute to human-caused climate change. Third Act, a climate activism group largely made up of retirees, organized the nationwide events ahead of annual meetings where investors can propose changes to corporate policies.

San Francisco climate activists chained themselves together outside a Wells Fargo branch in the rain.

In Washington, D.C., protesters sat in rocking chairs outside banks while the crowd cheered on people who cut up their credit cards in protest.

Mary McCabe, 61, from the Boston suburb of Arlington, made a poster with a baby picture of her son, to put a face on the younger generations she's striving to protect. It was the first time, she said, she took part in a demonstration like this.

"We keep hearing reports in the news every day about how our window for preventing catastrophic damage keeps closing and that really this decade is critical for us to take action," McCabe said.

Third Act co-founder Bill McKibben created the group to take advantage of the life experience, skills and political power of retirees. And the activists point out their economic influence too: Baby boomers own over half of U.S. wealth.

"Part of the thing that's really interesting about today [Tuesday] is that, for once, it's not just being left up to young people to do this work," said McKibben, who was in Washington, D.C., for the protest there. "That's important in this case, in part, because older Americans have about 70% of the country's financial assets. So it's particularly appropriate that they're putting pressure on here."

That message wasn't lost on Bob Follansbee, 73, who biked a half-hour from his home in Dorchester to downtown Boston. "I feel it's incumbent on us to stand up for the next generations coming and do what we can as the people who are, kind of, of age and of some resources," said Follansbee. He also said one of the reasons he went is that his generation is responsible for a lot of the climate change.

The demonstrations happened a day after a United Nations report was released showing that the world is on track to face catastrophic warming. However, world leaders already have the necessary tools to reduce greenhouse gas emissions and save lives, according to the report. The authors of the report hope it will give guidance for political leaders who will gather later this year for international negotiations on how to limit emissions.

McKibben said the world faces a "balancing act" trying to eliminate greenhouse gas emissions from the economy. "We're not going to be off oil and gas tomorrow, sadly," he said. "That's why we've been very clear in saying our only demand is that these guys [banks] stop funding the expansion of the fossil fuel industry."

Citi, one of the banks where protests happened Tuesday, said in an emailed statement that the bank "shares the goal of transitioning to a low-carbon economy." The company pointed to efforts to invest in "clean energy solutions through our net zero commitments and our $1 trillion commitment to sustainable finance." Citi also stated its commitment to its clients to "support their efforts to decarbonize their businesses."

Bank of America, another bank targeted by the climate activists, declined to comment.

Eric Compton, a bank analyst at Morningstar, a financial services company, said he didn't know of instances where protests like Third Act's affected a bank's decision-making. "Typically you need acts of [C]ongress or much more elevated political/branding pressure," Compton wrote in an email.

"The banks have also rejected shareholder resolutions in the past that would have limited funding of fossil fuels," Compton said. "At the end of the day, banks serve a complex set of interests and constituencies, so bringing about wide ranging changes through demands from a select group of constituents is difficult."

Still, McKibben remains hopeful. "We've had conversations now with executives at a couple of them [banks] who've reached out because they know what's going on," he said. "But I think it'll take a lot of work to really make them shift."

Third Act has gathered some 17,000 pledges from people who have said they'll close accounts and cut up credit cards if banks continue to support fossil fuels. The organization said in a news release that those pledges went to bank leaders at branches across the United States.

Paula Moura (@PaulaMoura_san) is a climate and environment reporter with NPR member station WBUR in Boston, from where she reported.

NPR's Seyma Bayram; Anna Canny, a reporter with member station KTOO; and Christopher Alam, a reporter with member station KQED, contributed to this story.