Thunberg, 16, has encouraged students to skip school to join protests demanding faster action on climate change, a movement that spread far beyond Sweden.

On Friday, about 40,000 students in Australia are expected to strike in as many as 55 separate protests as part of the School Strike 4 Climate campaign. That number is about twice that of a similar action in November, with over 100 nations likely to take part this time around.

Thunberg has been staging a Friday strike since last year, boycotting 42 days of classes since she began last year.

"The plan was to school strike for three weeks [in the run up to Swedish elections]," she said. "But at the end of that I wanted to go on. So then I started Fridays For Future ... The emissions are still going up so nothing has been achieved really."