Inspired by a Swedish schoolgirl, millions took to the streets in 2019 - as the world suffered extreme weather and major powers continued to block the radical action scientists say is needed to steer the planet away from a climate cliff-edge.
(SOUNDBITE) (English) SWEDISH CLIMATE ACTIVIST GRETA THUNBERG, SAYING: "People are suffering.
People are dying.
Entire ecosystems are collapsing.
We are in the beginning of a mass extinction, and all you can talk about is the money and fairy tales of eternal economic growth.
How dare you (crying).
2019 was the year the climate crisis found its voice - and not just that of a 16-year-old Swedish schoolgirl but also in the millions of what Greta Thunberg calls "angry kids" who took to the streets.
(SOUNDBITE) (English) YOUTH CLIMATE ACTIVIST, ZAYNE COWIE, 9 YEARS OLD, SAYING: "Please help us, please don't screw up our future." That voice has been met with resistance from some of the world's major greenhouse gas emitters.
U.S. President Donald Trump said Thunberg has to work on her "anger management problem"; Brazilian President Jair Bolsonaro called her a "brat".
In November Trump officially started the process of withdrawing the U.S from the 2015 Paris Climate agreement saying he needed to protect the U.S. energy market.
(SOUNDBITE) (English) U.S. PRESIDENT, DONALD TRUMP, SAYING: "I'm not going to lose that wealth, I'm not going to lose it on dreams, on windmills" Bolsonaro has dismissed international pressure as the Amazon rainforest - seen as vital to fighting climate change - burned.
(SOUNDBITE) (Portuguese) BRAZILIAN PRESIDENT, JAIR BOLSONARO, SAYING: "It's a fallacy to say that the Amazon is part of world heritage and wrong to say, as scientists affirm, that our rainforests are the lungs of the world." Indigenous communities say his policy of opening up the Amazon for development has fueled deliberate fires.
More than 3,000 square miles were destroyed in the first nine months of the year - ten times the area of New York City.
From Typhoon Hagibis in Japan and the Philippines to record temperatures in Europe, bushfires in Australia to Hurricane Dorian, the worst natural disaster in the history of the Bahamas - extreme weather touched every corner of the planet in 2019.
In developing nations, it was often a death sentence.
More than 1,000 dead when Cyclone Idai tore through Mozambique, Zimbabwe and Malawi in March.
More than 1,600 in India's heaviest monsoon season for 25 years.
In the face of this suffering, campaigners hoped that a UN summit at the end of the year would see global powers spurred into action.
Instead, governments have been accused of sleeping at the wheel as the Madrid event closed with only a weak commitment to the Paris agreement.
Secretary-General Antonio Guterres called it a missed opportunity.
The lack of a strong outcome has ratcheted up pressure for the next big climate summit in the UK next November when parties to the Paris agreement expected to boost their commitments to curb greenhouse gas emissions.
But with a lackluster international response at the end of a tumultuous year, progress may well hinge on whether the voice found in 2019 will be heard in 2020.