WATCH: Massive mural of Greta Thunberg stares down at San Francisco

San Francisco – A massive portrait of Greta Thunberg gazed down onto San Francisco on Tuesday night after an artist unveiled a mural of the Swedish teen activist in a bid to remind residents of the dangers posed by climate change.

The 60-foot tall, 30-foot wide (18-by-9 meter) mural was revealed hours after Thunberg announced on Twitter that she would be leaving the United States by boat on Wednesday, headed for a United Nations climate change conference in Madrid in December.

The teenager rejects air travel because of its high levels of greenhouse gas emissions.

Argentine street artist Andres Petreselli, who signs his work Cobre, says the portrait of Thunberg, 16, was unusual because he typically does not address politics, religion or sports.

“But, this one is … I feel connected with the politics behind (it) because I think it is real and if I have to compare it with the rest of my murals, this is the most political one that I ever made,” the 32-year-old said as he sat on a roof with the mural behind him.