SAN FRANCISCO ― California’s milestone climate change program was officially renewed Tuesday when Gov. Jerry Brown (D) held a public signing of a bill extending the state’s cap-and-trade initiative through 2030.

“A few weeks ago it did not look like it could happen,” said Brown, one of the program’s most passionate supporters, during the ceremony on San Francisco’s Treasure Island.

While the state Senate and Assembly narrowly passed the bill last week, it had faced pushback from both liberals and conservatives in the fraught lead-up to the vote.

Republicans argued that the cap-and-trade program, which has required polluters to obtain permits to emit greenhouse gases and enforced limits on those emissions since 2012, would stifle the economy. Environmental justice groups put pressure on Democratic lawmakers, contending that the bill was too friendly to the oil industry and didn’t go far enough to protect people who live near pollution sites.

Gov Jerry Brown signs cap and trade extension. Climate change law now runs until 2030 pic.twitter.com/rzYtCs6ZnQ — Mark Matthews (@MarkMatthewsNBC) July 25, 2017

Without the bill’s passage, the cap-and-trade program was set to expire in 2020.

“Nothing is more serious in the world than extinction,” said Brown, who has been working to reassure world leaders that Americans still intend to cut carbon emissions, even though President Donald Trump is pulling the U.S. out of the Paris Agreement.

“Once this stuff gets moving, you can’t turn it back,” the governor said, referring to climate change. “There are tipping points.”

Brown was joined by Assemblyman Eduardo Garcia (D), who introduced the bill; Senate President Pro Tem Kevin de Leon (D); San Francisco Mayor Ed Lee; and former Gov. Arnold Schwarzenegger (R), who signed the original legislation authorizing cap-and-trade on Treasure Island in 2006.

“I wish that in 2006 I had eight Republicans [voting for cap-and-trade],” Schwarzenegger said, referencing the GOP lawmakers who defied party expectations last week when they voted for the program’s renewal.

The passage of this bill is “a message that we have a functional government in California, where Democrats and Republicans work together,” Schwarzenegger said. “And I think this is a very important message for Washington.”