On the eve of the largest environmental conference in U.S. history, President Barack Obama on Wednesday urged island leaders to do more to preserve the planet and work together to fight climate change.

“Few people understand the stakes better than our Pacific island leaders, because they’re seeing already the impact: Rising temperatures and sea levels pose an existential threat to your countries,” he said.

Obama spoke at a combined reception for the Pacific Islands Conference of Leaders and the East-West Sustainability Summit at the East-West Center.

In the audience of about 200 were Pacific island leaders, former Hawaii governors, business leaders, prominent conservationists and leading scientists, plus Gov. David Ige, U.S. Sen. Brian Schatz, Honolulu Mayor Kirk Caldwell and other government leaders.

Outside, at least 200 people stood behind barricades hoping to catch a glimpse of the president. A group of protesters chanted that the military needed to leave Hawaii: “People of the world, scream and shout — U.S. military, get the hell out.”

Inside, Obama declared: “No nation, not even one as powerful as the U.S., is immune from a changing climate.”

Obama seemed to prod the Republican skeptics of climate change.

“While some members of the U.S. Congress still seem to be debating whether climate change is real or not, many of you are already planning for new places for your people to live. Crops are withering in the Marshall Islands. Kiribati bought land in another country because theirs may someday be submerged. High seas forced villagers from their homes in Fiji.”

Obama announced more than $30 million in new commitments to Pacific island countries, including funding for investments like stronger infrastructure, more sustainable development and safer drinking water.

With his presidency winding down, the president praised his own environmental record.

Over the past 7-1/2 years, America has worked to generate more clean energy, use less dirty energy and waste less energy overall, he said.

”And it’s made a difference. Our investments have tripled wind power, multiplied solar power thirtyfold, and, in many places, helped clean energy become cheaper than dirty energy. And we did all of this while fueling the longest uninterrupted streak of job growth on record,” Obama said

“So there is no conflict between a healthy economy and a healthy planet,” he said.

“I have to say that Teddy Roosevelt gets all the credit for starting the National Park System, but when you include a big chunk of the Pacific Ocean, we now have actually done more acreage,” he said to cheers.

He was referring to the announcement he made last week: the expansion of the Papahanaumokuakea Marine National Monument.

“Thanks to the hard work of many people in this room, including Sen. Schatz, I created the world’s largest marine preserve, quadrupling the size of our monument at Papahanau­mokuakea. This is an area twice the size of Texas that’s going to be protected, and it allows us to save and study the fragile ecosystem threatened by climate change,” he said.

The designation expanded the existing marine monument by 442,781 square miles, bringing the total protected area to 582,578 square miles.

The president noted a Hawaiian proverb that loosely translates to “unite to move forward.”

“It seems simple enough, but the natives used it as a reminder that if you want to row a canoe, every oar has to be moving in unison — otherwise, I don’t know, you go in circles. You just go around and around. Your pace slows, you drift. You get caught up in the currents, and you get off course,” he said. “Well, when it comes to climate change, there is a dire possibility of us getting off course, and we can’t allow that to happen.”

The president arrived on Air Force One at Joint Base Pearl Harbor-Hickam at 6 p.m. He was greeted by Gen. Terrence O’Shaughnessy, the commander of Pacific Air Forces, Schatz and Caldwell.

Obama, sounding tired after flying in from Nevada, spoke at the institution where his late mother, Ann Dunham, was a graduate student fellow in the 1970s. The occasion also marked his return to the Manoa campus of the University of Hawaii, where his parents met.

His closing remarks focused on his association with the East-West Center, saying that the occasion was especially meaningful because much of his life started within a mile radius of the center.

“My mother and father met probably a couple hundred yards from here. It’s true. I went to school about a mile from here. I was actually born about a mile from here. My grandmother and my grandparents lived most of their lives a short way away from here,” he said.

He noted that he has brought his children to Hawaii for Christmas every year for nearly two decades.

“I want to make sure that when they’re bringing their children here, or their grandchildren here, that they are able to appreciate the wonders and the beauty of this island and of the Pacific, and every island,” he said to applause.

More than 9,000 delegates from 194 countries convene in Honolulu for the International Union for Conservation of Nature’s World Conservation Congress. Opening ceremonies are scheduled for 10 a.m. today at the Neal S. Blaisdell Center and will feature remarks by U.S. Interior Secretary Sally Jewell and Ige.

The Pacific Islands Conference of Leaders, meeting at the East-West Center on Wednesday, discussed key regional issues including climate change and security.

The conference was founded in 1980 by former Gov. George Ariyoshi and Prime Minister Ratu Kamisese Mara of Fiji and is made up of the 20 heads of government from the Pacific islands region, convening every three years or so.

The Pacific islands are linked by the world’s largest ocean and by the threat of the climate crisis. Climate change has resulted in rising sea levels, saltwater intrusion, coastal inundation and ocean acidification, among other things, leaving island communities vulnerable.

The East-West Sustainability Summit, scheduled to end today, is billed as a gathering of some of the world’s most influential philanthropists, conservationists and business and government leaders, many of whom also will attend the World Conservation Congress.

This morning Obama will leave Honolulu for Midway Atoll, where he is scheduled to receive a briefing from the U.S. Fish and Wildlife Service on the Papahanaumokuakea Monument. In the afternoon, the president will tour the island and then deliver a monument designation statement to the members of the press who follow him there.

In the evening Obama will return to Honolulu and remain overnight before leaving for China, where he will meet with Chinese President Xi Jinping and participate in his final G-20 Leaders Summit.