HONOLULU — Speaking to a group of Pacific island leaders and conservationists at the East-West Center here Wednesday, President Obama said the world needed to intensify its efforts to curb global warming through conservation efforts.

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

Obama mocked some members of Congress for “debating whether climate change is real or not” while island leaders were dealing with the reality of its impacts.

“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,” he said. “And no nation, not even one as powerful as the United States, is immune from a changing climate.”

Obama, who arrived in Honolulu after delivering a speech at the annual Lake Tahoe Summit in Nevada earlier in the day, said “conservation has been a cornerstone of my presidency” in part because he sees it as a way to lessen the impacts of climate change.

“Since taking office, I’ve protected more than 548 million acres of our lands and waters for our children and our grandchildren,” he said. “I have to say that Teddy Roosevelt gets the credit for starting the National Parks system, but when you include a big chunk of the Pacific Ocean, we now have actually done more acreage than any other president.”

World Wildlife Fund’s senior vice president of government and multilateral affairs David McCauley, who was in the audience, said in a statement that Obama was taking a “two-pronged approach” of cutting greenhouse gas emissions while also preparing for global warming’s impact. “In expanding Papahānaumokuākea Marine National Monument, the President is protecting one the most biologically diverse — and hopefully resilient — marine environments in the world.”

The president seemed nostalgic at moments, noting that several seminal events in his life had taken place not far from the site where he was speaking.

“I was telling my staff, a lot of my life started about a mile radius around here. My mother and father met probably a couple hundred yards from here,” he said, as the crowd laughed. “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.”