To some, she's a brave teenager who has battled her own problems to look at the bigger picture and actually do something about the state of the world. To others (mainly rabid right-wingers, the kind who storm government buildings in order to overthrow democracy) she's an unwitting tool of the hard left who has no idea what she's talking about. Can you imagine the hate that runs through someone to the extent that they feel compelled to lash out at a Swedish schoolgirl rather than address the concerns she and many others have about the future of the planet?

As this Storyville film shows, Greta Thunberg has more courage in one of her pigtails than the likes of Trump or Bolsonaro have in their entire corrupt bodies: rather than bullying from the safety of a press conference she puts her convictions where her mouth is. The prime example of this is her journey in 2019 to address the UN in New York, rejecting a flight on environmental grounds and instead travelling by boat, Ellen MacArthur style, vulnerable to the elements for a trip that takes torturous weeks on water instead of a few comfortable hours by air.

I Am Greta lays out her story from campaigning solo in front of the Swedish parliament in 2018 to becoming a reluctant global figurehead of the movement that aims to turn back the tide of climate change. While there are some flashes of her life as a proper teenager (getting slightly grumpy at her dad and faceplanting into her pillow or doing silly impromptu dances), plenty questions are left dangling. How did filmmaker Nathan Grossman get the lowdown on the unknown Thunberg in order to capture that footage of her sitting outside parliament receiving support and love (as well as some gentle disdain) from passing strangers?

The issue of her Asperger's is somewhat skirted over, so we learn little about the way it really affects her daily life as well as how it hasn't diluted her determination to get the world's impending doom placed higher on the political agenda. There may well be another film to be made of Thunberg when she's older and has either dialled back her activism or taken it to more intense levels. As the closing segment of I Am Greta shows, there may be other young voices to step in if she's had enough of adults in power continuing to let her generation down.

Watch on BBC iPlayer.