Millions of people are expected to walk out of school and work on Friday, kicking off a week of protests calling for action to combat climate change.

The so-called global climate strike is part of a movement led by the 16-year-old activist Greta Thunberg. In the past year, children have left school to protest — and Friday's protests invited adults to join.

Hundreds of thousands of people have taken part in protests in Australia, Thailand, Bangladesh, India, Turkey, Kenya, Germany, the UK, and other countries, and protests are due to continue around the world.

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Millions of people around the world are expected to walk out of school and work on Friday as part of the global climate strike inspired by the 16-year-old climate activist Greta Thunberg.

It is the first of several planned events ahead of and during the United Nations Climate Action Summit next week.

Strikes started in Australia on Friday morning. School Strike 4 Climate, the organizers of the event, say over 300,000 people took part across the country.

The protests and strikes are spreading across the planet over the course of the day, reaching Asia, Africa, Europe, and North America.

"This is basically the only way to have our voice heard," Nishtha Sharma, 17, of Melbourne, Australia, told Business Insider.

Here's a look at some of the protests: