"The world is going its merry way, with a few notable exceptions, and climate change is building up in very soon-to-be irreversible ways that will very dramatically increase human suffering," the 77-year-old governor told Catholic News Service in Rome.
Brown was scheduled to speak July 21 and 22 at meetings organized by the Pontifical Academy of Sciences on climate change, human trafficking and the UN's sustainable development goals. Most of the participants were mayors from about 60 cities around the world.
In the encyclical, Pope Francis had written specifically about the role and responsibility of politicians in enacting policies to safeguard the environment and counteract climate change.
"In the absence of pressure from the public and from civic institutions, political authorities will always be reluctant to intervene, all the more when urgent needs must be met," the Pope wrote. "To take up these responsibilities and the costs they entail, politicians will inevitably clash with the mindset of short-term gain and results which dominates present-day economics and politics. But if they are courageous, they will attest to their God-given dignity and leave behind a testimony of selfless responsibility.
"A healthy politics is sorely needed, capable of reforming and co-ordinating institutions, promoting best practices and overcoming undue pressure and bureaucratic inertia," the Pope wrote in Laudato Si'.
"I don't think it's any harder for a politician to think longer-term than it is for a businessman; they are both interested in short-term perspectives," said Brown. But on climate change, the governor said, "if we keep on the path we are on now, millions and hundreds of millions will suffer and die. So there is an inter-generational responsibility to those who are not born yet.
"Right now the response to climate change is inadequate and in many countries, it's completely inadequate, so we need new voices. And one of the new voices is Pope Francis," he said.
"This intervention by the Pope," Brown said, "is appropriate and absolutely essential to wake people up to the dangers of climate change and to the value of seeing human beings as part of nature and dependent on nature as opposed to be adversaries of each other."