"We can still turn this around," Thunberg, 18, told thousands of protesters in front of Germany's parliament, the Bundestag, in Berlin.
Thunberg and prominent German climate activist Luisa Neubauer also accused politicians of falling short, saying the programs of the country's political parties were not far-reaching enough to limit global warming.
“There are natural disasters all over the world,” said fellow protester Quang Paasch, 21. “We are frustrated and angry. We need structural change, a social plan and actions that are based on scientific evidence.”
The protests organized by Fridays for Future, which was inspired by Thunberg, were the first such mass action since the coronavirus pandemic began.
In Germany, activists' calls have taken on renewed urgency after heavy rains in July killed at least 180 people and devastated cities across Western Europe. Global warming has made these kinds of events between 1.2 and 9 times more likely, according to a study by the World Weather Attribution initiative, which assesses the role of climate change in the aftermath of the extreme weather events.
The climate crisis prompted Henning Jeschke, 21, to declare a hunger strike three weeks ago.
"Nothing has been done," he told NBC News in a makeshift camp near the protest two days ahead of Germany's federal election. "We want leading politicians to publicly declare that Germany is in a climate emergency."
Awareness about the climate crisis in Germany is higher than ever, with young protesters hoping to pressure candidates to discuss the issue with them.
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Thunberg also joined Friday’s demonstrations in Berlin, and planned to address protesters in front of the Bundestag.
The protests were taking place five weeks before the United Nations COP26 summit, which has been billed as the last chance for world leaders to commit to dramatically cutting greenhouse gas emissions — vital to prevent the most disastrous effects of global warming.
U.N. Secretary-General António Guterres said Tuesday that the world was “seemingly light years away” from reaching climate targets.
According to him, there needed to be 45 percent cut in emissions by 2030, but per current national trends, emissions are expected to go up by 16 percent.
A study by Britain's University of Bath also found that 58 percent of children and young people surveyed said they were "being betrayed" by governments over climate change inaction, while 64 percent said their political leaders are not doing enough to avoid a climate catastrophe.
Elsewhere, Disha Ravi, an Indian climate activist who became a symbol for the nation’s crackdown on dissent during mass farmers’ protests, demonstrated in the southern city of Bengaluru on Friday. Protests also took place in the nation's capital, New Delhi.
In the Philippines, dozens of protesters gathered in the capital Manila, according to Fridays for Future. In Japan, several protesters held signs and slogans supporting the movement. New Zealand’s capital, Wellington, also joined calls for the strike, with Fridays for Future sharing video from the demonstrations on Twitter.
Also Friday, Paralympian gold medalist James Brown was sentenced to 12 months in prison by a judge in a London court after being found guilty of public nuisance for climbing on top of a plane at London City Airport during an Extinction Rebellion climate protest in 2019, the organization said in a statement.
Andy Eckardt reported from Berlin, Rhea Mogul reported from Hong Kong.