She has addressed world leaders and top economists, had an audience with the pope and been named Sweden's woman of the year. The teenager's role in driving a youth climate movement has made her a global icon.
The morning of August 20, 2018, the first day back at school after the summer break, was perhaps one of the last of Greta Thunberg's life to be truly private. That was the morning the 15-year-old first sat down outside the Swedish parliament in Stockholm, a lone figure with a piece of cardboard hand-painted with the words "Skolstrejk för klimatet" — school strike for the climate.
For three weeks leading up to the Swedish parliamentary election, Thunberg skipped school. After that, she began to strike every Friday, pledging to continue boycotting classes for as long as it took for the Swedish government to live up to the Paris Agreement on climate change. On her Twitter account, she called her campaign "Fridays For Future."
From the first of those Fridays, she was no longer alone outside parliament but joined by others who believed in what she was doing. The movement soon spread to other Swedish towns and across national borders to Germany, Belgium, the UK and elsewhere. By early 2019, #fridaysforfuture had become a truly global movement, with strikes on every continent.
In industrialized countries, fears over climate change have been building over recent years. There has been a buzz over veganism, zero waste and trends like plogging. But Thunberg's school strike took things a step further, capturing the urgency of the crisis with a revolutionary energy that has driven young people out on to the streets.
In just three months, Thunberg became so well-known that she gave a speech at the UN Climate Conference in Katowice in Poland. Apparently unperturbed by the size of her audience, the teenager told the adults in the room and around the world, that they were "not mature enough" to speak the truth.
"Our biosphere," she said, "is being sacrificed so that rich people in countries like mine can live in luxury. It is the sufferings of the many which pay for the luxuries of the few."
A few weeks later, she attended the World Economic Forum in Davos, where she delivered her message to some of the world's most rich and powerful.
"I want you to panic, I want you to feel the fear I feel every day," she told them. "And then I want you to act, I want you to act as if you would in a crisis. I want you to act as if the house was on fire, because it is."
Since then she has addressed a UN climate summit in New York, the EU parliament in Strasbourg, the French National Assembly in Paris and the House of Commons in London. Time and again, she has impressed upon her audience the urgency with which they must take scientific predictions seriously and do something to stop global warming, or face drastic consequences.
Meetings with global figures such as UN Secretary General António Guterres, Pope Francis, German Chancellor Angela Merkel, former US president Barack Obama and Arnold Schwarzenegger don't appear to faze Thunberg as she doggedly persists in raising the alarm.
In March, she criticized a draft of the EU's climate law — binding legislation to help the bloc reach its goal of net zero emissions by 2050 — as a "surrender" when she visited European Commission President Ursula von der Leyen in Brussels.
In a meeting with Merkel and other climate activists in August this year, Thunberg called on the German leader to "be brave" and demanded EU countries "stop pretending that we can solve the climate and ecological crisis without treating it as a crisis."
Thunberg and German Fridays for Future activist Luisa Neubauer ask Merkel to halt Germany's investment in fossil fuels
By her own admission, Thunberg doesn't like being the center of attention. But speaking on German television, she said she couldn't complain because she'd put herself in that position. "It's a small price to pay, knowing that you have an impact."
By launching what has become a global school protest movement, she has achieved what scientists and climate conferences alone have not: putting climate protection at the top of the public agenda.
Thunberg might not relish the limelight, but she understands how to stage her appearances. Before the coronavirus pandemic shut down international travel, for example, the teen regularly promoted climate-friendly transport on social media — tweeting selfies from trains, or from the yacht that delivered her to last year's UN climate conference in Madrid.
The pandemic led to school closures and children staying home, slowing the youth movement's momentum as political priorities shifted to a new crisis. Thunberg and her global following were forced to put their mass protests on hold and instead resort to online campaigns, letters to political leaders and "digital strikes."
The Fridays for Future movement last month held its first global action since the start of the virus outbreak, with students joining strikes in more than 3,000 locations. Protesters were asked to wear masks and social distance, and the numbers were far lower than the hundreds of thousands who took to the streets for climate marches in 2019.
Young people were asked to wear masks and observe social distancing for the global day of action in September, 2020
Not all the attention Thunberg attracts has been positive. Far-right, populist climate-deniers in particular have gone online to agitate against her, but criticism has come from elsewhere on the political spectrum, too. In Germany, politicians such as Paul Ziemiak, Secretary General of the Christian Democrat party (CDU), and Christian Lindner, leader of the Free Democratic Party (FDP) have publicly criticized Thunberg's message.
That the young activist has Asperger syndrome has also been a talking point. Her opponents allude to it having made her vulnerable to becoming a naïve victim of the green lobby.
In an interview with German public broadcaster ARD, Thunberg said she was saddened by such hatred, but added that "since they are doing that, writing those things, it means that what we are doing, what the school strike movement is doing, is having an impact, and that they feel threatened by it. So I think it's a positive sign."
She went on to say that if she didn't have Asperger's, she "would have continued like everyone else, not noticing something was wrong. But I am different, I think different, I work differently."
She says that if she believes something is important, she devotes herself to it 100%. Which is why she took a year off school to dedicate herself to activism.
This article was first published in August 2019 and was updated in October 2020.