Greta Thunberg is already known around the world for her climate change activism, but the Swedish teenager has also shown she is good at managing the media with her actions at the United Nations Climate Change Conference, or COP25, in Madrid.

When reporters made their way to the room where Thunberg was expected to have a news conference on Monday, they learned that she was not going to speak.

"It's our moral duty to use that media attention," she said of herself and Luisa Neubauer, a young German climate activist. "Luisa and I want to use our platform and to lend our voices to those who need to tell their stories. It's the people, especially from the Global South, and from the indigenous communities who need to tell their stories."

The Global South is a term used to refer to low-and middle-income countries in contrast to the high-income nations of the Global North. Thunberg described the indigenous people as "among the ones who are being hit the quickest and most by a climate and environmental emergency" but, she said, they "have been living in balance with nature for hundreds of years ... so we need to listen to them because they have valuable knowledge we need in facing this climate crisis."

Carlon Zackhras, from the Marshall Islands, a Pacific islands group located between Hawaii and the Philippines, urged world leaders to take action.

In February, Marshall Islands President Hilda Heine even talked about elevating the islands to fight climate change since rising sea levels and erosion are set to make most island atolls uninhabitable by 2050. "When you are in trouble, you find new solutions to face it," said Zackhras.

Arshak Makichyan, from Russia, said previously that he had not cared about climate change, but now he demonstrates in Moscow's Pushkin Square every Friday. "I am spending all my time trying to do something. ... I am afraid of not doing enough," Makichyan told world leaders. "We are not going to give up. We are getting stronger by the hour. We need to grow stronger. We need your help and we need everyone's help. Please act now."

Rose Whipple, who represents indigenous people in the United States, and has fought both in court and in protests against the building of several gas pipelines, said the climate crisis is more than a discussion about 1.5 C. "The climate crisis is a spiritual crisis for our entire world," she said.

Nakabuye Hilda Flavia, from Uganda, said developed countries should be ashamed of themselves. "You have dreams, but we have dreams too. But these dreams have turned into nightmares," she said. "Our future is right now being negotiated away by world leaders without our say."

Another delegate, Angela Valenzuela of Chile, said the rich and powerful seem happy to sacrifice their communities in the pursuit of profits. "Our planet is not for sale," she told world leaders.

Compared to previous gatherings, youth activism is one of the main focuses of COP25. On Friday, the day she arrived in Madrid, Thunberg led a 500,000-strong climate march in the city.