MIDWAY ATOLL — President Obama, taking his campaign to confront climate change to a pristine spit of land in the remote Pacific Ocean, said on Thursday that it was critical to examine the effects of the planet’s warming on the seas and to protect wild areas from degradation caused by human activity.

“Part of what we’ve been trying to do is provide some visual aid to understanding what’s happening” with climate change, Mr. Obama said in a brief interview here, looking out over lush vegetation and a lagoon so iridescent it turned the clouds above an otherworldly shade of green.

That means “being able to highlight the incredible beauty of a place like this, but also recognizing that if oceans continue to get warmer, that a lot of the marine species here could be affected, and ultimately that’s going to have an impact on human populations,” Mr. Obama said.

Mr. Obama traveled to Midway, part of the uninhabited Northwestern Hawaiian Islands, to recognize his expansion last week of Papahanaumokuakea Marine National Monument, the world’s largest protected area and home to more than 7,000 species of wildlife, some of them endangered and others found nowhere else.