Swedish teen Greta Thunberg started her environmental advocacy work as a solo act, when she refused to go to school in August in order to pressure her government to take more drastic climate action.
The 15-year-old has since inspired many more students around the world to do the same. And yesterday, she joined scores of other protesters in a march calling on leaders and people all over the world to do more to combat global warming as the final week of the United Nations climate change conference - or COP24 - began in Poland.
"We have had conferences like this before, and nothing came out of it. There needs to be less talking, and more action," Greta told The Sunday Times ahead of the march.
"The adults can't expect us to live with the mess they've left behind."
Beginning at 12.45pm from Wolnosci Square, some 1.5km from the COP24 conference venue, the march drew thousands of people of all ages and nationalities, carrying banners and signs with messages such as "1.5 deg C to survive", "no future in coal" and "save the humans".
Speaking to the crowd, Greta said: "We do need hope, of course we do. But the one thing we need more than hope is action."
And act, the protesters did, as they marched the 3km route - under the watchful eye of Polish police clad in anti-riot gear - while calling on world leaders at COP24 to adopt an ambitious and quick climate action plan to limit global warming to just 1.5 deg C above pre-industrial levels.
CLEAN UP THE MESS
The adults can't expect us to live with the mess they've left behind.
SWEDISH TEEN GRETA THUNBERG , speaking to The Sunday Times ahead of yesterday's march.
Czech Republic graduate student Carolina Formankova, 24, donned a panda outfit at the march to raise awareness of the impact of climate change on wildlife. "We want politicians and people in power to (do something), and save Earth and the animals."
Filipino artist and Typhoon Haiyan survivor Amado Guerrero Jano, 43, told The Sunday Times: "The world leaders like statistics. They like to talk about economics and business figures.
"But we refuse to be just statistics. There are human lives at stake. Three million were displaced during Haiyan. And if we don't limit global warming to 1.5 deg C, this will be multiplied by thousands."
Mr Jano had walked from the Vatican City in Rome to Poland over 65 days, arriving only last Friday night, to play his part in raising awareness about climate change.
The 24th session of the Conference of the Parties to the UN Framework Convention on Climate Change, or COP24, is particularly important as countries will be negotiating exactly how to implement the Paris Agreement, drawn up at COP21 in 2015.
The agreement, signed by almost 200 countries, including Singapore, set out a framework for the world to pursue actions to limit global warming to at least 2 deg C above pre-industrial levels, with a bolder target of 1.5 deg C, to avoid catastrophic climate change.
This year's meeting aims to flesh out the framework by coming up with a Paris rule book.
There are many issues to be hammered out in the negotiations, including things such as how the climate pledges of each country will be monitored; issues related to finance for developing countries, and also transparency.
Mr Masagos Zulkifli, Singapore's Minister for the Environment and Water Resources, is due to arrive in Katowice tomorrow, ahead of the high-level segment of the talks on Tuesday. He will deliver Singapore's national statement on Wednesday.