It is a proposal that has been long considered by the White House, and while it is championed by environmentalists and conservationists, it has caused consternation among and is resisted by those who say they will be negatively affected by it. But President Barack Obama will further his conservation legacy — after already protecting more public land than any U.S. president — Friday when he will announce more than quadrupling the size of Papahānaumokuākea Marine National Monument off Hawaii.

The marine monument was established by Obama’s predecessor, George W. Bush, who created it in June 2006. In July 2010, the area was designated a World Heritage Site by Unesco. It is already bigger than all the other national parks in the country put together. Obama will increase the size of protected land and water area inside its borders from the current 139,797 square miles to 582,578 square miles, making it the largest protected area in the world.

According to its website, “the extensive coral reefs” in Papahānaumokuākea “are home to over 7,000 marine species, one quarter of which are found only in the Hawaiian Archipelago. Many of the islands and shallow water environments are important habitats for rare species such as the threatened green turtle and the endangered Hawaiian monk seal, as well as the 14 million seabirds representing 22 species that breed and nest there. Land areas also provide a home for four species of bird found nowhere else in the world, including the world's most endangered duck, the Laysan duck.”

A group of Native Hawaiians had first asked Obama in February to consider expanding the monument’s boundary. And Brian Schatz, a Democratic senator from Hawaii, made a formal proposal about it in June. Reacting to the upcoming announcement, he told Reuters: “The best science shows that the ocean can recover, if you allow it to. … As daunting as the problem of climate change is, and as troubling as the situation is with respect to our oceans, they show remarkable resilience, if you give them a chance.”

A protected area status will include “a ban on commercial fishing, from 50 miles to 200 miles around the remote” Northwestern Hawaiian Islands, a fact that has caused some islanders and lawmakers to question the “scientific justification or conservation benefit” behind the move.

Sean Martin, president of the Hawaii Longline Association, told the Washington Post: “For somebody [environmental organizations] to feel good, we’re going to force U.S. fishermen out of waters.”

Papahānaumokuākea Marine National Monument Expansion President Barack Obama will Friday announce expansion of the Papahānaumokuākea Marine National Monument, making it the world's largest protected area. Photo: The Pew Charitable Trusts

Obama will travel to his native Hawaii next week, where he will address a global conservation conference in Honolulu.