China’s “first climate striker” Ou Hongyi was detained in Shanghai’s main shopping district on Friday after organising a silent protest, prompting teen environmentalist Greta Thunberg to criticise China’s treatment of activists. Hongyi, 17, said in an Instagram post on Sunday that she and three other protesters, were detained after three hours of “silent resistance” in front of the Shanghai Exhibition Centre. “Billions of people will die, and children will die while parents lose their jobs. Nonviolent civil disobedience climate movement is the only candle in the darkness to give us a slightest hope,” she said. She said she was stopped in the eastern part of Nanjing Road, a popular shopping district, and taken to a nearby police station. She was released the same day. On Sunday, she posted a photo on Twitter of what looked like an interrogation room. Howey Ou, China’s version of Greta Thunberg, pays price for climate activism “We just went on the global climate strike day , with four people, advocates, on Nanjing Road which is a very symbolic place in Shanghai, and we are just arrested and interrogated for about two hours and I just came out of the police station,” she said in a video after her release. In the Twitter post on Sunday she said she was forced to write a “self-criticism letter”, a forced admission of guilt frequently used by Chinese police to intimidate activists. “Government is the only institution that has the ability to protect its people but it failed,” she wrote. She initially agreed to speak to the South China Morning Post on Tuesday morning but later attempts to contact her were unsuccessful. It is unclear whether Hongyi was charged while in detention. Authorities in Shanghai have not issued a statement about Friday’s protest. The Shanghai protest was part of Fridays for Future , an international campaign in which children boycott school on Fridays to raise awareness about climate change. According to the campaign’s office, there were 3,300 protest last Friday as part of a global climate action day. Could China take the lead in setting new global conservation goals? Activist Greta Thunberg, who started the campaign, spoke out in support of Hongyi. “Activism is not a crime. Peacefully standing up for the future survival of the living planet should never be illegal. Solidarity and gratitude to our friends in China, Uganda, Russia and everywhere else #FridaysForFuture activists are being arrested,” Greta said on her Twitter account. Inspired by Greta, Hongyi skipped classes for a week last year to protest in front of the government office in her hometown of Guilin in southern China. She held up a poster asking citizens to join her in a strike to highlight climate change, attracting widespread attention. Hongyi’s activities have also attracted the attention of police, who cut short her protest last year. She has also been interrogated by officials from Guangxi’s Public Security Bureau. China’s state-funded and endorsed environmental NGOs have refused to allow Hongyi into their events. Her protest came just two days after Chinese President Xi Jinping pledged at the United Nations General Assembly that China would be to achieve carbon neutrality by 2060 . Thousands of young climate activists return to streets in worldwide protests Andreas Fulda, an associate professor at the University of Nottingham’s school of politics and international relations in Britain, said environmental campaigns had been much harder to run since Xi came to power. “During the Hu and Wen era it was still possible for environmental NGOs to run campaigns, such as against wasteful energy consumption or reckless dam building in southern China,” Fulda said, referring to former president Hu Jintao and former premier Wen Jiabao who were in office between 2002 and 2012. “Since Xi has come to power, the available space for Chinese civil society has shrunk dramatically.” Fulda added that Greta’s defence of Hongyi was “admirable” because it strengthened an increasingly repressed Chinese civil society. “Such transnational solidarity with what could be termed ‘unofficial China’ is of great importance. Chinese citizens who are willing to speak truth to power should be supported by the international community,” he said. But Greta is unlikely to try to put more pressure on the Chinese authorities. The teen activist received a wave of backlash last year after she responded favourably to a tweet by Hong Kong activist Joshua Wong Chi-fung urging Greta to hold China accountable for being the world’s largest emitter of greenhouse gases. Greta did not respond to a request for comment.