Further rallies are planned later Friday in the U.S., where organisers say more than 800 events are expected.
The St Albans event will take place on September 20 at the Clock Tower from 9am to 11am.
The protests follow the lead of Swedish climate activistGreta Thunberg, who in August 2018 staged a school strike for the climate outside the Swedish Parliament.
The movement has taken hold in Europe, where climate has been catapulted to the top of the political agenda. "The ITUC, with over 200 million members around the world, is totally in support of your leadership".
Top schools around Australia are telling students they will not be penalised for participating in the School Strike 4 Climate. "We are the future and we deserve better", 12-year-old Lilly Satidtanasarn - known as "Thailand's Greta" for her campaigning against plastic bags in malls - told AFP in Bangkok. "This is the challenge of our future".
Suzie Longstaff, headmistress of Putney High School, a private girls' school, said young people should be able to make their own decisions about whether to take part in the action and that she applauded her students for having an environmental and social conscience.
SBS News talked to a group of students who made a sign saying "you'll die of old age, I'll die of climate change".
Jake Woodier, from the UK Student Climate Network, said: "Unions have a rich history of fighting for progress, so for the global climate strike to have the backing of The International Trade Union Confederation adds massive weight behind our calls for taking immediate action".
This is the third climate strike for 10-year-old Chloe Cook.
Greta Thunberg told the Associated Press on Friday that she watched news of strikes in Australia and the Pacific before she went to bed in NY the night before.
Students walked out of their classrooms in schools across York to lead the protests, as they have been doing in a series of climate strikes which began in February.
More action is needed by countries to bridge the gap between the measures they have already promised and what is needed to prevent temperature rises of more than 1.5C (2.7F) or 2C (3.6F) and avoid the worst impacts of the climate crisis. "Time is running out".
"Our leaders aren't listening, so we obviously need to make more noise".
"We're telling adults to step up and back us up with our strikes because we need everyone to tell the leaders at the global climate summit that they need to take climate action", she said.
Local musicians will also meet outside Broadway Cinema at 11.30am for "climate strike busking" at various town locations.
Chambers said they protest so they have a voice since they are still too young to vote in the upcoming federal election. We as the youth of our country know the problem of climate change.
The police urged everyone attending the climate strike to go to Millbank, "where in conjunction with the organisers we have created a safe space for protest". "Strikes are a loud and powerful mechanism that empowers and encourages the people to take action and act with sovereignty".
As the sun rose above the worldwide dateline, events began in the deluge-threatened Pacific Islands of Vanuatu, the Solomons and Kiribati - where children chanted "we are not sinking, we are fighting".
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