Greta Thunberg has resumed her climate change protest outside Sweden's parliament after returning home following a four-month round-the-world tour.

The 16-year-old activist joined protesters in Stockholm at a Fridays for Future rally, which she began in August 2018 and has since catapulted her to worldwide fame.

Thunberg uploaded a photo of herself to Instagram clutching her now-famous 'school strike for climate' banner along with the caption: 'School strike week 70. Stockholm!'

The schoolgirl's dogged activism has seen her invited to speak at parliaments across the world, give a speech to the UN, and become Time's Person of the Year.

Greta Thunberg rejoined the climate protest which made her famous outside Sweden's parliament on Friday, clutching her 'school strike for climate' banner

The 16-year-old began her weekly protests in Stockholm in August 2018, and has since become a love-her-or-hate-her icon in the fight against climate change

Thunberg returned to Sweden this week after a four-month round-the-world tour, during which she addressed the UN, was invited into parliaments and became Time Person of the Year

For the last four months she has been taking her protest to countries around the world without using planes because of their environmental impact.

Thunberg's transatlantic odyssey August 14: Sets sail from Plymouth, England. August 28: Arrives in New York, USA. She takes in Washington, D.C. Montreal, Quebec, Iowa City, Iowa, Standing Rock Indian Reservation, South Dakota, Denver, Colorado, Vancouver, British Columbia, and finally Los Angeles, California. She had planned to travel south to Chile for the COP25 climate summit but because of political unrest it was relocated to Madrid. 'It turns out I’ve traveled half around the world, the wrong way,' she tweeted in November. November 13: Sets sail from Hampton, Virginia. December 3: Arrives in Lisbon, Portugal. December 9: Takes part in a massive rally in Madrid for COP25. December 13: Fridays for Future protest in Turin, Italy. December 14: Train from Basel, Switzerland, north through Germany. December 17: Posts photo with her dogs in Stockholm ('Home!') Advertisement

The epic voyage saw her cross the Atlantic from the UK to America before visiting cities across the US and Canada, then returning to Portugal earlier this month.

From there she went by train to a climate summit in Spain - which ended without an agreement - before visiting Turin and Basel on her way back to Sweden.

She celebrated her return on Tuesday by posing with her pet dogs, Moses and Roxy.

During her last climate protest in Turin, Italy, she threatened to 'put world leaders against the wall' if they continued running away from their climate obligations.

She later apologised for the remark, made after the summit in Madrid, claiming that a Swedish phrase had been lost in translation.

'Yesterday I said we must hold our leaders accountable and unfortunately said "put them against the wall". That's Swenglish: 'att ställa någon mot väggen' (to put someone against the wall) means to hold someone accountable. That's what happens when you improvise speeches in a second language.' Ms Thunberg wrote.

'But of course I apologise if anyone misunderstood this. I can not enough express the fact that I - as well as the entire school strike movement - are against any possible form of violence. It goes without saying but I say it anyway.'

And that followed on the heels of another high-profile Twitter storm after Thunberg was named TIME's 'Person of the Year.'

Thunberg - then 15 - is pictured protesting outside the Swedish parliament on November 2018

Greta Thunberg with Moses the golden retriever and Roxy the black Labrador at Stockholm's harbour on Tuesday morning, captioning the picture: 'Home!'

Thunberg's odyssey began when she set sail from Plymouth, England, on August 14 and arrived in New York at the end of that month. She then made her way across to Los Angeles preparing to journey to Chile for the COP25. But her plans changed when the conference was moved to Madrid and she sailed from Hampton, Virginia on November 13 and arrived in Lisbon, Portugal on December 3

President Donald Trump - who was given the accolade in 2016 - tweeted that she had 'anger management problems' and told her to 'chill'.

Thunberg responded by changing her Twitter bio to include the words 'currently chilling'.

Thunberg's journey through Germany was the last leg of a continent-spanning trip which began when she travelled to New York on a low-emissions yacht in August.

Th 16-year-old activist started a worldwide movement last year when she began to strike from school every Friday to protest government inaction on climate change.

Refusing to fly, she has twice crossed the Atlantic by boat in recent months in order to speak at a UN climate summit in New York and the hastily rearranged COP25 summit in Madrid.

Thunberg, who most recently attended the COP25 climate summit Madrid, had a rocky journey home after she lashed out at Europe's largest rail operator on Saturday, tweeting that she had been an 'overcrowded' train through Germany