Governments must respond to growing concerns expressed by children about the effects of the climate crisis and other environmental emergencies on their lives and futures, a UN body has said.

In a strongly worded formal opinion published on Monday, the Committee on the Rights of the Child concludes that the triple planetary crisis – the climate emergency, the collapse of biodiversity and pervasive pollution – “is an urgent and systemic threat to children’s rights globally”.

The committee outlines the immediate risks that children face from poor air and water quality, a lack of food safety and exposure to toxic pollutants such as lead – especially children with disabilities, belonging to minority or Indigenous groups, and living in areas vulnerable to climate breakdown and disasters.

It also points to structural challenges that pose a longer-term threat, such as greenhouse gas emissions, the unsustainable use of resources and ecosystem degradation.

Children are demanding action on these interconnected crises, said 14-year-old Francisco Vera, a UNICEF youth advocate for environmental and climate action in Latin America and the Caribbean, “precisely because adults haven’t taken the responsibility for it”.

The UN opinion spells out, for the first time, that states have a duty to safeguard a clean, healthy and sustainable environment for young people alive today, as well as future generations.

“While the rights of children who are present on Earth require immediate urgent attention,” it says, “the children constantly arriving are also entitled to the realisation of their human rights to the maximum extent.”

Aoife Nolan, professor of international human rights law at the University of Nottingham, said this statement serves as a “crucial tool for those arguing for climate justice at both the international and national law levels”.

Furthermore, governments are responsible for foreseeable environment-related threats arising as a result of their current acts or omissions, “the full implications of which may not manifest for years or even decades”.

Some submissions to the committee had asked it to take a stronger stance on state responsibility to mitigate climate change, noting the International Energy Agency’s warning that there can be no new investment in coal, oil or gas if the world is to reach net zero by 2050.

The final UN opinion says delaying a rapid phase-out of fossil fuels will result in higher global emissions and greater harm to children’s rights, but only urges states to take this “into consideration”.

The committee chair Ann Skelton, professor of law at the University of Pretoria and director of the Centre for Child Law in South Africa, said some of the language in the document was strengthened but the committee sought to keep “a little bit of a margin” for states to fulfil their duties, adding that its members are “not experts on the environment”.

The UN body does, however, pay tribute to children’s efforts to draw attention to environmental crises. The committee, which is responsible for monitoring the implementation of the Convention on the Rights of the Child, received 16,331 contributions from children in 121 countries, who described how their health, lives and communities were being harmed.

Under the convention, children should be “recognised and fully respected as environmental actors”.

The opinion stresses that children have a right to be heard on crucial matters such as climate change.

“Children’s voices are a powerful global force for environmental protection, and their views add relevant perspectives and experience with respect to decision-making on environmental matters at all levels.”

Greta Thunberg, the environmental activist, inspired more than a million children all over the world to take part in a series of high-profile school climate strikes over the past few years, and young people are leading a significant portion of the growing number of climate lawsuits around the world.

This month, a judge ruled in favour of young plaintiffs in a landmark case seeking to hold the state of Montana to account for its climate impacts, and in September a group of young people in Portugal are due to appear before the European Court of Human Rights to confront 32 countries, including all EU member states, the UK, Norway, Switzerland, Russia and Turkey. The youngest people in these cases are aged just five and 10.

“Advocacy from young people is hugely important in changing the parameters of societal, political and media discussion around environmental protection,” said Nolan.

In 2021, the UN Committee on the Rights of the Child rejected on technical grounds a landmark claim by a group of young people, including Greta Thunberg, that countries perpetuating the climate crisis were violating their human rights.

Skelton said that, although the case was not accepted, it did set a groundbreaking development in international law that states are responsible for harming people outside their borders.

“It also certainly galvanised the committee’s interest in deciding to issue this general comment. The case made us so aware of how children were feeling about these issues, how strongly they were fighting to get their views across.”

Amid a global crackdown on human rights defenders and climate activism, the committee also says governments must protect children engaging in environmental protests.

“The exercise by children of their rights to freedom of expression, peaceful assembly and association, to information and education, to participate and be heard and to effective remedies can result in more rights-compliant, and therefore more ambitious and effective, environmental policies.”

Francisco Vera said some people still believe children’s opinions are not valid, “but the potential for change is greater compared to the past when children were not listened to”.

Skelton hopes governments will use the document to improve their policies and laws to better protect children, to involve children at all levels and to get tougher on corporations.

“The states are the ones that ratified the convention, therefore we hold them accountable,” she said.