NICOLA Sturgeon has backed youngsters who are skipping school to take part in global warming protests, describing their actions as a "cause for optimism in an often dark world".

The First Minister spoke out as school children in Scotland joined in the global demonstration, despite claims from the UK Education Secretary that the strikes “won’t do a thing” for the environment.

Sturgeon said the Scottish Government was a "world leader" in acting against climate change, the urgency of the issue meant "it is right that we are all challenged to do more and that we hear the voice of the next generation".

The movement has already seen school strikes in Australia and European countries including Belgium, and has been inspired by teenager Greta Thunberg, who protests every Friday outside Sweden's parliament to urge leaders to tackle climate change.

The strikes come in the wake of a UN report which warned that limiting global temperature rises to 1.5C above pre-industrial levels, beyond which climate impacts become increasingly severe, requires unprecedented action.

That includes cutting global carbon dioxide emissions by almost half within 12 years.

Students in the UK are demanding the Government declare a climate emergency and take active steps to tackle the problem, communicate the severity of the ecological crisis to the public and reform the curriculum to make it an educational priority.

They also want recognition that young people have the biggest stake in the future, should be involved in policymaking, and that the voting age should be lowered to 16.

Teenager Holly Gillibrand from Fort William is one of those taking part in the the protest, saying it would be a "momentous day".

She tweeted: "Young people all around the UK are uniting together in solidarity to demand that our leaders treat the climate and ecological crisis as the crisis it is."

The National: Thousands joined climate demonstrations in BelgiumThousands joined climate demonstrations in Belgium

The National Association of Head Teachers (NAHT) said it supports the right of young people to express themselves but it did not condone students being out of the classroom to take action.

In a statement, the NAHT said: "While a school leader's role is to ensure children attend school, are kept safe and receive a good quality of education, it is right that individual school leaders can decide how best to respond to any proposed protest by students in their school on Friday."

Education Secretary Damian Hinds claimed the strikes would be a burden for teachers.

He said: "I want young people to be engaged in key issues affecting them and involving themselves in causes they care about.

"But let me be clear, missing class won't do a thing to help the environment; all they will do is create extra work for teachers."

However, Scottish Green Party education spokesman Ross Greer urged education bosses to back pupils who are taking part in the protests rather than punish them.

He said: "I commend every young person in Scotland and across the world who is joining this growing movement and speaking out against this existential threat to their future."

He stressed the Curriculum for Excellence system in Scottish schools "is based on the idea that we support our young people to become responsible citizens".

Greer added: "Every school student who takes action against the climate crisis on Friday is doing exactly that.

"They should know that they will not be punished for defending their own future.

"They have the Scottish Greens' support and I hope they will have the support of their teachers and education authorities."