Millions of people around the world are expected to join global demonstrations demanding action on climate change today.
Inspired by Swedish schoolgirl Greta Thunberg, young people and adults are being urged to take to the streets to protest against global warming.
In what is being billed as a 'global climate strike', thousands of people will skip school or work to call on the Government to make tackling climate change a priority.
Friday's climate strike follows on from nationwide protests earlier this year as part of the Youth Strike 4 Climate, and this time the young eco-activists have asked adults to join the in protests.
Organisers are hoping for the biggest ever climate change protest in history today, with NGOs, unions and global companies such as Amazon all backing the call.
Here's all you need to know about the global climate strike:
When is the climate strike?
The first strike will take place on Friday, September 20 and is designed to coincide with a UN emergency climate action summit in New York, with a second strike being held on September 27.
Different organisations have signed up for different strike dates.
Where are strikes taking place?
People in around 150 countries are to take time off school or work to join the global event, such as America, Australia, Germany, India and Japan.
In the UK there will be more than 200 events and demonstrations as part of the week-long protest, with tens of thousands of people expected to take part.
Labour leader Jeremy Corbyn is due to address a rally of climate strikers outside Parliament, while other events are being held across the country.
Strikes will take place across the UK again, with the main one happening at Millbank in Westminster at 11am. Other strikes in the capital are due to take place in areas including Islington, Bethnal Green and Hammersmith.
Birmingham, Manchester, Edinburgh, Glasgow and Belfast will also host protests, among others.
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The TUC has announced it will support the strikes and UNISON has announced action plans across the UK, from Lambeth and Tower Hamlets to Salford, Scotland and Doncaster.
Universities have also thrown their weight behind a number of planned walkouts, as has the PCS union, Unite, NEU and global behemoth Amazon.
What is the climate strike?
School student Greta Thunberg inspired a global movement when she sat in front of the Swedish parliament building to demand action on climate change, inspiring the Fridays for Future movement.
Fridays for Furture evolved into the Youth Strike for Cimate movement, which says its students are "driven by an alarming lack of Government leadership on climate action over previous decades."
The coalition is calling on the Government to declare "a state of climate emergency" and educate the British public in the seriousness of global warming.
They are also demanding changes to the school curriculum which will include education about climate change.
The coalition wants young people to be included in decision-making and is also calling for the voting age to be lowered to 16.
It eventually evolved into the Global Climate Strike movement, which says it needs millions of people to "disrupt business" all over the world, either by protesting or raising awareness in their communities.
Global Climate Strike says humanity needs "to act right now to stop burning fossil fuels", but that "it's going to take all of us working together to succeed".
It says protests will demonstrate that people "are no longer willing to continue with business as usual", with the "urgency of the climate crisis" requiring a "new approach and a just response".
Who is Greta Thunberg?
Greta Thunberg is a teenage schoolgirl from Sweden who has made headlines for her action against climate change.
In August 2018, Greta decided she would stop going to school on Fridays, choosing instead to picket outside the Swedish parliament (Rikstag) to raise awareness of global warming.
Her mission was to pressure the Swedish Government to pass legislation that would reduce carbon emissions in line with the Paris Agreement.
Since her strike action began, she has addressed world leaders at the COP24 United Nations climate change summit and the World Economic Forum.