State and local leaders will gather at the summit from May 15 to 17 to discuss the effects of rising temperatures in their communities, with the goal of broadening the conversation from combating climate change to include strategies to adapt to the reality of a warming planet.

Newsom, who aides said will talk about the impact of fire, flood and drought on California, is expected to be one of a few speakers to address the pope and more than two dozen leaders from around the world.

“This year holds unprecedented significance for democracy and the climate, two intertwined issues which will define our future,” Newsom said. “With half the world’s population poised to elect their leaders amidst a backdrop of escalating political extremism, and global temperatures hurtling towards alarming new heights, the stakes could not be higher. There is no greater authority than moral authority — and the Pope’s leadership on the climate crisis inspires us all to push further and faster. “

Francis is the first pope to make climate change a top priority of his papacy, seeking to marry scientific facts about greenhouse gas emissions with a moral call to the 1.3 billion Catholics worldwide and leaders across the globe to protect the planet for future generations. Critical of the lack of urgent action, the Pope called climate deniers “foolish” in his first interview on U.S. television last week.

For Newsom, a Catholic, the invitation from the Vatican provides an opportunity to show that he’s aligned with Francis and appeal to the 50 million Americans who follow the religion. The trip also gives the Democratic governor an international stage to stress the importance of 2024 elections — and the choice between President Biden and former President Trump — on the climate crisis.

Biden is considered a friend of the climate movement and his Inflation Reduction Act, a 2022 law to increase renewable energy production and decrease greenhouse gas emissions, is one of the nation’s largest climate investments. The president has sought to reduce the country’s reliance on coal and gas plants, which Trump has said he would reverse.

Former Gov. Jerry Brown used his visit to the Vatican in 2017 to deliver a scathing critique of Trump’s climate policies. The visit came months after Trump withdrew from the Paris climate accord.

Lauren Sanchez, Newsom’s climate advisor, also pointed to elections in India, Mexico and other nations as critical to climate change efforts this year.

Veerabhadran Ramanathan, a professor at the Scripps Institution of Oceanography at UC San Diego, serves in Pope Francis’ Council for the Pontifical Academy of Sciences and helped organize the event. He said invitations were limited to international mayors and governors, including Govs. Maura Healey of Massachusetts and Kathy Hochul of New York. President Biden and other world leaders were not invited to attend, but representatives of his administration will be present, Ramanathan said.

Ramanathan said pressure is on international heads of state to cut emissions, but adaptation starts “bottom up.”

“The key thing is to ask yourself, if there’s drought, and then there’s a fire in our backyard, who is fighting it?” Ramanathan said. “Not presidents of the nation. It’s the mayors and governors. We want to give them sort of a blueprint of how to deal with it.”

Ramanathan said California is a leader on climate change and the council felt it was important to hear from the state at the summit.

Newsom is expected to repeat the message that the “climate crisis is a fossil-fuels crisis” and call out the role of oil companies.

“We think the governor stands alone among elected officials around the world who are really willing to say that this crisis is created by the burning of coal and oil and gas, and that we need to move away from those fossil fuels as quickly as possible,” Sanchez said.

In honor of Earth Week, Newsom announced a plan last week to transform more than half of the state’s 100 million acres of land into multi-benefit landscapes that absorb more carbon than they release. The plan is part of Newsom’s strategy to curtail emissions and reach carbon neutrality in California by 2045. The challenge includes other ambitious targets, such as requiring all new vehicles sold in California to be hybrid or electric by 2035.

Newsom’s visit to the Vatican is expected to be brief, with the governor touching down Wednesday, speaking at the conference the following day and wrapping up his engagements on Friday. His delegation includes a few members of his staff. Wade Crowfoot, California’s natural resources secretary, is also expected to speak.

Newsom’s travels have drawn criticism from his GOP critics, who contend he should be focusing exclusively on problems in California such as the state’s massive budget deficit.

The governor went to China in October to promote climate cooperation with a short stop in Israel in the early stages of the war with Hamas. He left the state again the following month to debate Florida Gov. Ron DeSantis in Georgia and has campaigned in other states in support of Biden’s bid for reelection.