Extinction is a fictionalized account of last year's Extinction Rebellion protests in Britain that features Thompson - who herself took part in the demonstrations - as an activist.

Director and co-writer Jack Cooper Stimpson said he hoped the film's online release on Friday would act as a reminder that there is still much to be done.

"I'm so aware that the world is a complicated place right now, we've had Brexit we've had pandemics and god knows what else so it's not been easy," he told the Thomson Reuters Foundation.

"But nonetheless, nothing has happened and it's been really hard to witness."

Britain's government did not immediately respond to a request for comment.

Britain's declaration on May 1, 2019 came after a high-profile visit by the campaigner Greta Thunberg and 11 days of protests that the Extinction Rebellion group cast as the biggest act of civil disobedience in recent British history.

Read also: Celebrities back call for climate action in Extinction Rebellion video

Another wave of protests followed in October.

"It is great that parliament declared a climate emergency last year, but unfortunately not much has been done to tackle the issue since," said producer Henry Rouquairol.

"Hopefully, this film in whatever small way can reignite the debate again."

The film's producers said they kept their carbon footprint low by limiting transport to essential trips, using public transport and sourcing sustainable catering and costumes.

Shot during the protests, the film's release comes as climate activists seek to do more online, restricted by coronavirus lockdowns.

Thompson said she hoped it would highlight the frustration of protesting for change.

"I hope this film makes protest seem as useful and as maddening as it is," she said in a statement.