Before Fonda was arrested, she delivered a short speech, during which she said that "we make personal choices like driving an electric auto or going vegan, recycling, and we think that that's enough".
The 81-year-old Academy Award-winner was one of 16 people arrested for unlawfully protesting and was charged with "crowding, obstructing or incommoding", police said.
On Thursday, the actress vowed to join Friday protests at the Capitol "inspired and emboldened by the incredible movement our youth have created".
She wrote on her website: 'I can no longer stand by and let our elected officials ignore - and even worse - empower - the industries that are destroying our planet for profit.
"The image of Jane Fonda, Barbarella, Henry Fonda's daughter, sitting on an enemy aircraft gun was a betrayal", she said in 2005, "the largest lapse of judgment I can imagine". She said she had wanted to take a year, but was able to get just the shorter amount of time, after which she will go back to Hollywood, finish recording her hit series, and return to protest more.
"We have to be sure that the crisis that is climate change remains front and center like a ticking time bomb", Fonda told the station.
Fonda echoed those statements in an interview with The Washington Post, saying, "I'm going to take my body, which is kind of famous and popular right now because of the [television] series, and I'm going to go to DC and I'm going to have a rally every Friday".
"What we're facing is so important and so urgent, it doesn't matter".
"It so traumatized her that she stopped eating".
"So four months is what I could get", she said.
But despite her lefty credentials, Fonda told Politico in 2018 that while she opposes President Trump's policies, she doesn't hate him as a person.
"I do not know Mr. Giuliani's motives for attacking me", she says. It earned her the nickname "Hanoi Jane".