Students across the UK are joining their peers around the world in walking out of their schools to demand politicians take urgent action on climate change.

Young people have already taken to the streets in Europe, India, Australia, New Zealand and Japan, with around 2,000 events expected to be held in more than 120 countries.

The global day of action against climate change was inspired by Greta Thunberg, a teenager who has protested outside Sweden’s parliament every Friday to urge leaders to take action and has been nominated for a Nobel Peace Prize.

In the UK, students gathered in Parliament Square in London with placards reading: “By the time we’re in charge it will be too late”, “we want you to panic” and “the greatest threat to the planet is the belief someone else will save it”.

They chanted “this is what democracy looks like” while primary school children, who were at the protest with their parents and holding handmade placards, shouted “climate change, boo!”

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Organisers said they expected a larger turnout on Friday than the UK’s first strike on 15 February, which saw thousands of students ditch school for demonstrations.

In Berlin, at least 10,000 protesters, mostly students, gathered in a central square waving signs with slogans such as ”There is no planet B” and “Climate Protection Report Card: F”, before a march through the capital’s government quarter.

In Poland, thousands marched in Warsaw and other cities to demand a ban on the burning of coal.

In India’s capital New Delhi, schoolchildren protested over inaction on climate change and rising air pollution levels that often far exceed World Health organisation limits.

Several thousand students gathered around the Pantheon building in Paris. Some criticised French president Emmanuel Macron, who sees himself as the guarantor of the Paris climate accord but has been lambasted by climate activists for being too business friendly and not ambitious enough in his efforts to reduce French emissions.

Police in Vienna said around 10,000 students rallied in the Austrian capital, while in neighbouring Switzerland a similar number protested in the western city of Lausanne.

In Helsinki, police said about 3,000 students gathered in front of Finland’s parliament sporting placards such as “Dinosaurs thought they had time too!”

Students in the UK have staged events in 100 British towns and cities including London, Edinburgh, Canterbury, Oxford and Cambridge.

They demanding the government declare a climate emergency and take active steps to tackle the problem, and have called on politicians to communicate the severity of the ecological crisis to the public and reform the curriculum to make it an educational priority.

They also want recognition that young people have the biggest stake in the future, to be involved in policymaking, and for the voting age to be lowered to 16.

It follows in the wake of a UN report published last year which warned limiting global temperature rises to 1.5C above pre-industrial levels, beyond which the impact of climate change would become increasingly severe, requires unprecedented action.

It would require cutting global carbon dioxide emissions by almost half within 12 years, and slashing them to zero by mid-century.

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In a video released ahead of the strikes on Friday, environment secretary Michael Gove tells students walking out of lessons and lectures to call for urgent action on cutting emissions: “Dear school climate strikers, we agree. Collective action of the kind you’re championing can make a difference, and a profound one.”

Labour leader Jeremy Corbyn also backed the strikers, tweeting: “Thank you for standing up against climate change. You shouldn’t have to pay the price for the mistakes of previous generations.”