I Am Greta: Movie tells climate activist's 'coming of age' story

From unknown school girl to world famous climate change activist, the documentary I Am Greta chronicles two years in the life of Greta Thunberg.

It was filmed almost single-handedly by Swedish director Nathan Grossman, who originally thought he would be lucky if her story made a short feature for the local news.

Environment correspondent Justin Rowlatt reports.

Read more: Thunberg's 'surreal' adventure told on big screen