First it became a national monument. Now it's on the short list to become an international treasure.

The Papahanaumokuakea Marine National Monument, otherwise known as the Northwestern Hawaiian Islands, has been nominated by the U.S. for the World Heritage List, which recognizes the most significant cultural and natural sites on the planet.

Hawai'i Volcanoes National Park is already on the list. So are the Grand Canyon, Russia's Lake Baikal and the Great Barrier Reef.

Making the list would be a fitting honor for the world's largest marine conservation area, which covers 137,792 square miles and is home to more than 7,000 marine species, including the endangered monk seal.

The monument is also a prized resource for research, not only for the unique sea life among its thriving coral reefs but for its historical significance: as a home to ancient Hawaiians and in later history, host to whalers, explorers and world war, including the Battle of Midway.

But honors are no guarantee of protection against environmental degradation.

Among other threats, Papahanaumokuakea sits just south of a vast plume of ocean debris, including abandoned nets that entangle wildlife and small pieces of plastic that birds and fish mistake for food. Protecting this preserve will mean changing habits of consumption and waste disposal that extend far beyond the monument's boundaries.

Perhaps that's the most encouraging news behind the possibility of being named a World Heritage Site. It would become a treasure for the world, and the world's responsibility to help protect.