Greta Thunberg sums up 2019 in five ominous words

Climate change activist Greta Thunberg has summed up 2019 in five ominous words.

Inspired by the end-of-year Twitter hashtag #2019in5words, the 16-year-old tweeted one of her most famous quotes: "Our house is on fire."

Thunberg delivered those words as part of a speech at Davos 2019, where she called on leaders to take drastic action to tackle climate change.

"Our house is on fire. I am here to say, our house is on fire," she said.

"We are facing a disaster of unspoken sufferings for enormous amounts of people. And now is not the time for speaking politely or focusing on what we can or cannot say. Now is the time to speak clearly.

"Either we choose to go on as a civilisation or we don’t. That is as black or white as it gets. There are no grey areas when it comes to survival."

Thunberg became famous for starting an environmental campaign in August 2018 which became a global movement, initially skipping school and camping out in front of the Swedish parliament to demand action.

She was named Time magazine's Person of the Year for 2019 earlier in December.

"In the 16 months since, she has addressed heads of state at the UN, met with the Pope, sparred with the President of the United States and inspired four million people to join the global climate strike on September 20, 2019, in what was the largest climate demonstration in human history," the magazine said.

She's the youngest-ever recipient of the annual award, which has been running since 1927.