Tens of thousands of protesters joined rallies on Friday as a day of worldwide demonstrations calling for action against climate change began ahead of a UN summit in New York.
Some of the first rallies in what is being billed as a "global climate strike" were held in Australia's largest city, Sydney, and the national capital, Canberra.
Australian demonstrators called for their nation, which is the world's largest exporter of coal and liquid natural gas, to take more drastic action to reduce greenhouse gas emissions.
Organisers estimate more than 300,000 protesters took to Australian streets in what would be the largest demonstrations in the country since the Iraq War began in 2003.
Protests were staged in 110 towns and cities across Australia on Friday, with organisers demanding government and business commit to a target of net zero carbon emissions by 2030.
Similar rallies were planned Friday in cities around the globe.
In the United States more than 800 events were planned, while in Germany more than 400 rallies were expected.
In New Delhi, one of the world's most polluted cities, dozens of students and environmental activists chanted "We want climate action" and "I want to breathe clean" at a rally outside the Ministry of Housing and Urban Affairs.
They carried banners with some displaying messages like "There is no Earth B."
Hundreds of people marched in Thailand's capital and staged a "die-in" outside the Ministry of Natural Resources to demand the government declare a climate emergency, ban coal energy by 2025 and completely replace fossil fuel energy with renewable energy by 2040.
In Hong Kong, where near-daily protests all summer have demanded greater democracy, about 50 people found a different reason to demonstrate: climate change.
Carrying banners and posters, they chanted "Stop the pollution" as they marched along the harbour front under a blazing sun.
The protests are partly inspired by the activism of Swedish teenager Greta Thunberg, who has staged weekly demonstrations under the heading "Fridays for Future" over the past year, calling on world leaders to step up their efforts against climate change.
Many who have followed her lead are students, but the movement has since spread to civil society groups.
Similar coordinated protests in March drew crowds around the world.
Australian Associated Press