They were outside the Sir Charles Frossard House early this morning.
William Carter co-coordinator of the group and author of the Guernsey Climate Strike petition said the strike was the first of its kind in Guernsey.
'Hundreds of thousands of people are taking part across the world, we want to share something with that.
'That this is a strike, during the week, is important rather than being on a Saturday or evening because this is peacefully disruptive.
'Somebody said, if Greta [Thunberg] had done her protests on a Saturday, we wouldn't know who she was. There may be fewer people because of the time we are doing it but we hope this is the start of something bigger.'
Islanders were encouraged to come to the protest however worked best for them and many took the time as holiday rather than striking from work, which unions had not agreed with.
Those who expressed interest but were unable to attend have been able to sign the online petition written by Mr Carter which will be given to the States on 18 October.
Mr Carter took the day as time in lieu.
'People will have taken leave, or a lunch break, it's about withdrawing our labour.'
'We could be doing other things with a day off, at the beach or the cinema but we are here,' he said.
Karen Lenormand, who is self-employed, and her son Jean-Paul, 12, had come to the event.
'It's a no brainer,' said Mrs Lenormand.
'We need to take action now instead of in a couple of years, we should have taken action 100 years ago so we need to make a stand today,' said Jean-Paul.
'I'd like to see the date [of the Environment and Infrastructure Climate Change Action Plan] a bit earlier.
'There's no reason why it can't be in half a year,' he said.
The pair were also holding signs made by islanders at the Ron Short centre for physically disabled people so that even though those who wanted to go could not attend, they were still represented.
Alex Bowtle was also there with her two-year-old daughter Winter.
'We just came to support the cause. I want to make sure the world is the best it can be for her as she grows up.'
Ms Bowtle said it was important to bring Winter to support the event.
'Already if she sees litter on the floor she'll pick it up and she knows what the recycling bins are for.'
BOX: The protest, and related petition demand three things:
1) That the States of Guernsey commit to a decarbonisation target date of 2030. Mr Carter said although Jersey has one and the UK will soon bring theirs to 2030, Guernsey does not have a target at all. 'Better to reach 80% of the target then have no target at all,' he said.
2) To bring forward the release of the Climate Change Action Plan because May 2020 is too late, they would like to see increased priority and resource be given to deputies and civil servants working on the plan.
3) Input came from school students and they would like to see release of further information about renewable energy targets an increased priority for replacing fossil fuels with renewables.
The petition can be found on www.change.org by searching Guernsey Climate Strike.