The UN Climate Summit has been graced by the likes of actor Leonardi DiCaprio and US President Barack Obama, but the haunting words of a young mother from a tiny Pacific Island nation have made the most lasting impression.

Spoken-word poet Kathy Jetnil-Kijiner, 26, from the Marshall Islands, was just one of four people chosen from 544 nominees to address the opening of the UN Climate Summit in New York.

In front of an audience of 120 state dignitaries, Jetnil-Kijiner performed a poem she wrote for her seven-month-old daughter, in which she promises to protect the child from the threat of climate change, which she says world leaders are ignoring.

In her impassioned performance, Jetnil-Kijner used the metaphor of a "lagoon that will devour you" to depict the sea levels that are threatening to swallow her island home.