As the UN Climate Change Conference (COP26) starts at the end of the month, the issue is high on the agenda.
Here we look back to 2019, when students took time off school to march through Oxford and call for action.
Greta Thunberg inspired young people all over the world to stage climate strike rallies and her infectious enthusiasm prompted ‘school’s out’ demos in Oxford throughout 2019 - halted only by the coronavirus lockdown.
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The first protest took place in the city centre in February 2019 and they were still being held about a year later until the rallies were halted by the coronavirus and social distancing restrictions.
One of the biggest climate strike demos was in Broad Street in September 2019.
It was the city's seventh Youth Strike 4 Climate protest, inspired by child activist Ms Thunberg.
Kaitlyn Gresty, 13, from Thame and Karen Young, 10, from Oxford were at the strike in Broad Street.
Kaitlyn said at the time: "Your generations had a future but we are being told we don't have the same opportunities. It's not fair."
The location moved from Bonn Square to Broad Street, to accommodate more people, and adults were also urged to join in.
Similar strikes were planned across the country and around the world.
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Evan and Cian Wyse from Wallingford were at the Broad Street strike with their dad, Paul.
Ten-year-old Cian said: "It's important to be here so that polar bears have a home and so the Arctic doesn't melt."
Kelsie Jesson, 20, and her mother Tracey, 52, from Drayton also travelled to Oxford for the strike.
Kelsie said: "It is scary because we don't know what will happen in the future. By the time people realise there is a problem it will be too late to stop irreversible change."
And classmates at the Dragon School George Vine, Leo Sarooshi and Nabil Pucks all attended the climate strike with their parents.
Nabil, eight, said he had been watching the news and thought the effects of climate change were 'really scary'.
Chris Church, of Oxfordshire Friends of the Earth, said he though the crowds at the climate strike were unprecedented.
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He said: "This is the largest environmental demonstration Oxford has ever seen."
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