Hundreds of thousands of activists have mobilised in cities across the globe calling for action on climate change.
Celebrities and politicians joined business leaders and ordinary citizens to pack streets and public squares in more than 2,000 locations worldwide.
The biggest protests was held in New York City, where organisers said some 310,000 people took part in the day of action.
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Hollywood actor Leonardo DiCaprio, United Nation Secretary-General Ban Ki-moon and New York Mayor Bill de Blasio all marched down Sixth Avenue in what was proclaimed as the largest climate protest in history.
"Our mission is to make this a decisive moment, a turning-point moment and I felt today that I was seeing history starting to be made," de Blasio said.
There were also colourful and boisterous rallies in major cities in Latin America and Europe and as far away as India.
In Australia, around 1,000 protesters joined together in central Sydney on Sunday to form a human sign saying "beyond coal and gas".
In Melbourne, protest organisers said 30,000 people converged on the city's Treasury Gardens where they called for a 100 per cent renewable energy target and an end to coal mining.
Addressing the gathered protesters, Professor Tim Flannery said Australia must take action before it's too late.
"This is not some sort of ethereal issue," he said.
Greens leader Christine Milne said Australia must send a strong message to Mr Abbott that the time for a "conversation" was over.
In the UK, rallies in London pulled around 40,000 people, including actress Emma Thompson who told the crowds the threat from climate change was akin to a Martian invasion
The international day of action was designed to build pressure ahead of a United Nations-hosted climate change summit in New York on Tuesday.
Some 125 heads of state and government will be in attendance in the first such gathering since the failed Copenhagen climate conference in 2009.
UN member states have agreed to limit warming to two degrees above pre-industrial levels, although they have not said when this should be achieved.
Prime Minister Tony Abbott is arriving in New York a day after the climate summit and will send Foreign Minister Julie Bishop in his stead.
The rallies come as Australia's scientific research agency, the CSIRO, says global emissions of carbon dioxide from the combustion of fossil fuels reached a new record of 36 billion tonnes last year.
At the same time, the pace of emissions from burning fossil fuels continues to grow at a high rate, the agency says in the latest edition of the collaborative report, the Global Carbon Budget 2014.
Dr Pep Canadell - who is executive director of the Global Carbon Project and co-author of the 2014 report - said the carbon dioxide level was "unprecedented in human history".
He said fossil fuel carbon dioxide emissions are projected to increase 2.5 per cent this year, bringing the total carbon dioxide emissions from all sources above 40 billion tonnes.
