Edmund G. Brown Jr., the Governor of California, has announced his state is to host the world's climate leaders at a major summit in San Francisco.

The Global Climate Action Summit will take place in September 2018. In a statement on Thursday, Brown's office said California would convene representatives from subnational governments, businesses, investors and civil society at the summit.

Brown announced the summit via a video message at the Global Citizen Festival in Hamburg, Germany. "It's up to you and it's up to me and tens of millions of other people to get it together to roll back the forces of carbonization and join together to combat the existential threat of climate change," he said. "That's why we're having the Climate Action Summit in San Francisco, September 2018."

"I know President Trump is trying to get out of the Paris Agreement, but he doesn't speak for the rest of America," Brown went on to add. "We in California and in states all across America believe it's time to act, it's time to join together and that's why at this Climate Action Summit we're going to get it done."

Brown's office said that the summit would represent the first time a U.S. state had "hosted an international climate change conference with the direct goal of supporting the Paris Agreement."

Under the Paris Agreement, world leaders have committed to making sure global warming stays "well below" 2 degrees Celsius and to pursue efforts to limit the temperature rise to 1.5 degrees Celsius.

At the beginning of June, Trump announced the U.S. would withdraw from the Paris Agreement and commence negotiations to re-enter or negotiate a new agreement, prompting a barrage of criticism from supporters of the accord.

"This agreement is less about the climate and more about other countries gaining a financial advantage over the United States," the president said at the time.