Millions of people around the world held a global climate strike on Friday, inspired by activist Greta Thunberg.
Protesters across continents waved placards and chanted slogans in what could be the biggest ever demonstration over global warming caused by humans.
"Our house is on fire", Ms Thunberg said at a rally. "We will not just stand aside and watch."
The day began in the Pacific and Asia and culminated in a massive demonstration in New York.
It comes ahead of a UN summit next week at the organisation's headquarters in Manhattan. Activists are demanding greater efforts be made at the meeting to tackle climate change.
Ms Thunberg first started skipping school to protests against inaction on climate change in 2018.
Her actions have inspired schoolchildren and adults around the world to take up the fight.
Pacific island nations like Kiribati, the Solomon Islands and Vanuatu - all threatened by rising sea levels - kicked off the strike. Posts online showed citizens chanting: "We are not sinking, we are fighting."
In Australia, 350,000 people are thought to have joined protests across the country, with some local authorities encouraging school children and workers to take part.
The country is already suffering from soaring temperatures, and warming seas have contributed to the death of half the Great Barrier Reef off Australia's north-east coast.
From there, demonstrations spread to cities in Asia, Europe, Africa and the Americas.
Students in Ghana marched in the capital Accra, saying climate change has sped up coastal erosion which is affecting people on the country's coast.