Friday March 15th, 2019, will go down as a green-letter day in Ireland when a new generation of young environmentalists, energised by a lack of adult action on climate change, took over the national stage.

With public protests scattered throughout the country, the day of action by school climate strikers added up to an environmental stance of unprecedented scale.

More than 11,000 marched in Dublin; some 5,000 in Cork, a 1,000 in Ennis, 500 in Maynooth. There were thousands more at 35 venues on the island of Ireland.

Their action was in solidarity with 16-year-old Greta Thunberg who embarked on a lone strike outside the Swedish parliament last year. That sparked the Fridays For Future movement – an unstoppable force made possible by the good side of social media networks.

It culminated on Friday with its biggest statement yet; co-ordinated “school strikes” held across the planet from the South Pacific to the edge of the Arctic Circle.

With the backing of a solar-powered sound system, Theo Cullen-Mouze, a 16-year-old from Clare Island in Co Mayo, told the Dublin crowd: “Greta Thunberg has inspired me. We owe her more than mere words . . . Humanity has created a problem and humanity must solve it.”

He added: “Today I’m afraid for my future. Today, I’m afraid for the future of my 13-year-old sister . . . I’m afraid for the future of my family. I’m afraid for the future of humanity. But today I have hope. I see the faces of people who care. I see the faces of people who are tired of being told we don’t understand.”

The hundreds of posters on display had a disarming directness about the climate issue and political failure to address it.

“March now or swim later. . . The oceans are rising – so are we . . .Tick tock Taoiseach . . . Listen to your Mother. . . We are all in the same boat . . . Operation Green Nation....Human change not climate change...Show the Earth what it’s worth...Why study for a future when we won’t have a future.”

One displayed close to the stage was an arresting colour painting of Greta Thunberg with the words “Dublin for Climate Action”.

The teenager herself was continuing to deliver her blunt message, firmly aimed at adults and especially politicians. She told a rally in Stockholm that the world faces an “existential crisis, the biggest crisis humanity ever has faced, and still it has been ignored for decades. And you know who you are, you that have ignored this”.