The UN Secretary-General Antonio Guterres called climate change “the battle of his life”, but one that “we’re not winning”.

“As Secretary-General, I have many battles,” Mr Guterres tweeted on Thursday, adding “we need stronger political will and urgent climate action to save our planet and our future.”

Mr Guterres is visiting Fiji and the other South Pacific countries on the frontline of the battle against climate change.

According to estimates by the London School of Economics, up to 1.7 million of the 10 million living in the Pacific Islands could be displaced due to climate change by 2050.

In Tuvalu, an island country in the South Pacific where Mr Guterres travelled on Friday, could be one of the first places in the world to disappear because of rising seas. Tuvalu’s highest point is less than 5 metres (16 ft).

Penguin habitats threatened by climate change Show all 9 1 /9 Penguin habitats threatened by climate change Penguin habitats threatened by climate change Gentoo penguins on Ardley Island, Antarctic, where global warming has affected the glaciers that the penguins live on and has brought new species to compete with AFP/Getty Penguin habitats threatened by climate change Gentoo penguins on Ardley Island, Antarctic, where global warming has affected the glaciers that the penguins live on and has brought new species to compete with AFP/Getty Penguin habitats threatened by climate change Gentoo penguins in Cuverville Island, designated as an Important Bird Island. These penguins feed on krill but krill is growing scarcer due to climate change AFP/Getty Penguin habitats threatened by climate change Penguins on Ardley Island, Antarctic, where global warming has affected the glaciers that the penguins live on and has brought new species to compete with AFP/Getty Penguin habitats threatened by climate change Gentoo penguins in Cuverville Island, designated as an Important Bird Island. These penguins feed on krill but krill is growing scarcer due to climate change AFP/Getty Penguin habitats threatened by climate change Chinstrap penguins on King George Island. Global warming has affected the glaciers that the penguins live on and has brought new species to compete with AFP/Getty Penguin habitats threatened by climate change Gentoo penguins in Cuverville Island, designated as an Important Bird Island. These penguins feed on krill but krill is growing scarcer due to climate change AFP/Getty Penguin habitats threatened by climate change A penguin and a seal. Global warming has affected the glaciers that these animals live on and has brought new species to compete with AFP/Getty Penguin habitats threatened by climate change Gentoo penguins on Ardley Island, Antarctic, where global warming has affected the glaciers that the penguins live on and has brought new species to compete with AFP/Getty

While in Fiji, Mr Guterres held a joint press conference with Fiji Prime Minister Josia Furek Benimarama, calling climate change “a life battle for Fiji and the Pacific”.

He also boarded a solar-power traditional boat and participated in an interactive session with students at the University of the South Pacific on combating climate change, where he heard about their work.