Tony de Brum saw the effects of rising seas from his home in the Marshall Islands and became a leading advocate for the landmark Paris Agreement and an internationally recognized voice in the fight against climate change.
De Brum, who was the Pacific nation's climate ambassador and former foreign minister, died Tuesday in the capital Majuro surrounded by his family, according to Marshall Islands President Hilda Heine. He was 72.
After witnessing nuclear testing in the islands while growing up, De Brum also fought against nuclear weapons and for his nation's independence.
Heine described him as a national hero.
"The very existence of the Paris Agreement owes a lot to Tony de Brum," Heine said in a statement. "He was a giant of history, a legend in every meaning of the word, and a custodian of our shared future."
When the Associated Press visited De Brum at his Majuro home in 2015, he described how he'd grown up catching rabbitfish off Enebok Island, which was lush with coconut and breadfruit trees at the time.
But in recent years, the island has slipped beneath the water. During the visit with De Brum, all that remained at low tide was a pile of rocks that snagged flotsam including a sandal, some frayed rope and a sprouting coconut.
Although the Marshall Islands, population 70,000, remains one of the places most vulnerable to climate change because it protrudes just 6 feet above sea level, de Brum said at the time that he was determined to stay and fight.
"The thought of evacuation is repulsive to us," he said. "We think that the more reasonable thing to do is to seek to end this madness, this climate madness, where people think that smaller, vulnerable countries are expendable and therefore they can continue to do business as usual."
Heine said De Brum was out fishing with his grandfather at age 9 when he witnessed the horrors of "Bravo shot," a U.S. thermonuclear test at Bikini Atoll.
Born in Tuvalu, De Brum became one of the first residents of the Marshall Islands to attend a university. He returned home to become a leading participant in negotiations that secured the nation's compact of free association with the U.S. and membership to the United Nations.
Heine said De Brum remained committed to the cause of nuclear justice and global disarmament, as well as climate change.
During the negotiations for the Paris accord, De Brum helped form the "High Ambition Coalition" of 100 rich and poor nations and helped secure a global commitment to try to limit Earth's warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) compared with pre-Industrial times.
The U.S. signed up the accord under President Obama but President Trump announced in June that the nation would withdraw.
"He was incredibly important to all of us," said Marshall Islands poet Kathy Jetnil-Kijiner, who is related to De Brum. "He is viewed for his work globally, but he was also a grandfather, an uncle and a father, and was much more than his accomplishments."