Argentine muralist Andres Iglesias, who signs his art with the pseudonym Cobre, is set to finish the artwork of the Swedish 16-year-old in the city's Union Square by next week.
"Greta is small, she is tiny but her voice is strong and she said ' you have stolen my childhood and then she said ' you are continuing with business as usual".
Executive director Paul Scott said he believed Cobre was the flawless choice to create the first of what the organisation hopes will be a series of works honouring climate change activists.
"I usually don't paint political stuff, because it kind of gives you people who will love it and people who will hate it", Cobre tells TIME.
Scott said he hoped the mural would inspire people to "act".
"While we young people may not be able to vote or make decisions today, we have something just as powerful", she said.
Thunberg rose to prominence after striking from school in 2018 to demand action on climate change in her home country of Sweden.
The former UN High Commissioner for Human Rights and Ireland's first female president said it is the responsibility of everyone to take steps now to reduce their carbon emissions and other contributors to what she called "the climate emergency" currently facing the globe. "Change is coming whether you like it or not". President Donald Trump announced the USA would pull out of the agreement two years ago.
Trump had described her as a "very happy young girl" and an image of her giving the president a "death stare" at the United Nations building in NY went viral.
"My message is that we'll be watching you", said the teen activist, whose mural will now keep watch over San Francisco, acknowledged as a city embracing environmental mindfulness.