By Roberta Rampton

HONOLULU (Reuters) - President Barack Obama on Thursday was set to visit Midway Atoll, the remote coral reef that serves as a reminder of both modern global climate challenges and the dominance the United States has held in the Pacific since its World War Two victory there.

The island wildlife refuge is described by those who have been there as a kind of "Garden of Eden" where the world's oldest-known albatross returns each year to nest and the electric-blue ocean teems with fish.

The journey, timed as Obama leaves for his last visit to Asia to meet with Chinese President Xi Jinping and other world leaders, will also serve as a reminder of the American victory against Japanese forces on the island during World War Two.

"It's a signal, it's a message saying the United States is committed to staying in the Pacific, and not sort of backing away," said naval historian Tom Hone, who has studied the Battle of Midway.

Obama, whose presidency comes to an end in five months, was to focus on how conservation can help species adjust to changing climate and was to call for an expansion of international climate cooperation like the kind he forged with Xi in 2014.

He is also seeking to make Americans as passionate about the issue as he is. Less than 5 percent of American voters say the environment is the most important issue facing the country, according to Reuters/Ipsos polling between July 24 and Aug. 21, and 35 percent say climate change will not affect the way they vote in the Nov. 8 election to pick Obama's successor.

The island visit bookends Obama's trip last year to Alaska, where he hiked on a shrinking glacier, which he said was a "preview" of what would happen if climate change goes unchecked.

"These aren't 'photo ops' - I think these are real opportunities to help the American people understand," said Carol Browner, a former head of the Environmental Protection Agency who advised Obama on climate issues in his first term.

"He can get a level of attention that nobody else can get," Browner said.

Last week, Obama quadrupled the size of Papahānaumokuākea Marine National Monument to create the world's largest marine monument, protecting the area off the coast of Hawaii from commercial fishing and drilling.

Obama called Midway, which lies within the monument, "a hallowed site" that should be preserved.

"Ancient islanders believed it contained the boundary between this life and the next. Hundreds of brave Americans gave their lives there in defense of the world’s freedom," he said.

Obama's visit may conjure symbolism of American power in the Pacific ahead of his trip to China, a country many blame for a loss of American jobs and economic prowess.

The World War Two Battle of Midway, one of the most-studied battles in military history, tipped the balance of the U.S fight against the Japanese navy.

In June 1942, U.S. forces, tipped by code-breakers that the Japanese navy was planning an attack, sank four Japanese aircraft carriers and a heavy cruiser in a giant air and sea battle.

Many of the military buildings on Midway Atoll have been allowed to decay, and visitors have not been allowed since 2012 because of tight budgets, which dismays Jim D'Angelo, 79, a retired oncologist and history buff in Bradenton, Florida.

D'Angelo, who has been inspired by the battle since he read about it as a teen, went on to create a foundation that built a memorial on the island. He had hoped to one day see a museum built there.

"The fact that (American soldiers) went in even though they knew that they were going to die, it just captured my intellect and my emotions as representing the best that America really has to offer," D'Angelo said.

Kevin Foerster, the U.S. Fish and Wildlife Service's refuge chief for the region, said the agency would like to be able to open the island to visitors, but budget constraints and the remote island's fragile economy mean its beauty and history is better shared on the internet for now.

(Reporting by Roberta Rampton; Editing by Andrew Hays and Jonathan Oatis)