Greta Thunberg has been named Time's 2019 Person of the Year, becoming the youngest ever recipient of the title.

The activist, 16, inspired the school strikes for the climate movement after going alone to the Swedish parliament on Fridays.

The then 15-year-old held up a sign that read 'skolstrejk för klimatet', which translates as 'School strike for the climate'.

Since then she has become the face of the youth climate movement, drawing large crowds with her appearances at protests and conferences over the past year and a half.

Veteran campaigners and scientists have welcomed her activism, including her combative speeches challenging world leaders to do more to stop global warming.

Time editor-in-chief Edward Felsenthal told the Today show: 'She became the biggest voice on the biggest issue facing the planet this year, coming from essentially nowhere to lead a worldwide movement.'

He confirmed she is the magazine's youngest ever choice. Malala Yousafzai was runner up in 2012, losing out to Barack Obama, aged 15.

Greta Thunberg has been named Time's 2019 Person of the Year

Thunberg delivers a speech during the COP25 UN Climate Change Conference in Madrid on Wednesday. She accused political and business leaders of polishing their images rather than taking aggressive action in the fight against climate change at the UN climate talks

Thunberg's angry accusations that world leaders are failing the younger generation have made headlines, including her shouts of 'How dare you?' at the U.N. General Assembly earlier this year.

An image of her stare at Donald Trump as he entered the UN quickly became a social media meme.

This year's shortlist included Trump, Nancy Pelosi and the Hong Kong protesters.

When asked by the DailyMail.com about the president losing out to Greta, White House Principal Deputy Press Secretary Hogan Gidley replied: 'Huh?!?'

Politicians have, by and large, praised Thunberg, who has Asperger's syndrome, and her movement as an important voice of her generation.

Former Vice President Al Gore said Wednesday: 'Brilliant decision for @TIME to choose @GretaThunberg as its Person of the Year.

'Greta embodies the moral authority of the youth activist movement demanding that we act immediately to solve the climate crisis. She is an inspiration to me and to people across the world.'

Editor Felsenthal said Thunberg 'represents a broader generational shift in the culture', adding: 'She embodies youth activism'.

Shortlist of TIME's 2019 Person of the Year House Speaker Nancy Pelosi - central to the impeachment proceedings against Donald Trump. President Donald Trump - named TIME Person of the Year in 2016 and the 45th president of the United States. The Whistleblower - the anonymous CIA officer who reported Trump's call with Ukrainian president Volodymyr Zelensky The Hong Kong Protesters - mass protests first erupted in June against planned legislation that would have allowed criminal suspects to be extradited to mainland China for trial in Communist Party-controlled court. Greta Thunberg - winner Advertisement

The magazine says: 'In the 16 months since, she has addressed heads of state at the U.N., met with the Pope, sparred with the President of the United States and inspired 4 million people to join the global climate strike on September 20, 2019, in what was the largest climate demonstration in human history.'

'For sounding the alarm about humanity's predatory relationship with the only home we have, for bringing to a fragmented world a voice that transcends backgrounds and borders, for showing us all what it might look like when a new generation leads, Greta Thunberg is TIME's 2019 Person of the Year,' the media franchise said Wednesday on its website.

Last year The Guardians, journalists targeted or assaulted for their work, were handed the title. In 2017 it was The Silence Breakers, those who spoke out as part of the Me Too movement.

Thunberg was in Madrid on Wednesday, where she addressed negotiators at the U.N.'s COP25 climate talks.

There she accused political and business leaders of polishing their images rather than taking aggressive action in the fight against climate change at the UN climate talks.

The schoolgirl was seen at the UN headquarters in September with an enraged expression on her face as President Trump upstaged her entrance by walking in flanked by news reporters

Thunberg's accusations that leaders are failing younger generations have made headlines, including her shouts of 'How dare you?' at the U.N. General Assembly

In a speech the teenager also criticized governments for avoiding taking action to cut greenhouse gas emissions and 'not behaving as if we are in an emergency'.

Greta said: 'The biggest danger is not inaction; the real danger is when politicians and CEOs are making it look like real action is happening, when in fact almost nothing is being done apart from clever accounting and creative PR.'

She said the science showed that, at the current rate of emissions, the world is set to use up the whole 'carbon budget' - the amount of pollution that can be put into the atmosphere and still keep global warming to 1.5C - in eight years.

Swedish climate activist Greta Thunberg, 16, arrives in New York after a 15-day journey crossing the Atlantic in the Malizia II, a zero-carbon yacht in August