A United Nations body on Monday updated a key treaty designed to protect children’s rights to strengthen their hand in fighting climate change, as they emerge at the forefront of the battle to protect the planet.

From wildfires in Portugal to fossil fuel projects in the U.S. state of Montana, young plaintiffs have been taking the lead in a burgeoning number of lawsuits seeking more government action on climate change.

In the document, the U.N. Committee on the Rights of the Child calls environmental degradation, including the climate crisis, “a form of structural violence against children”.

It says that states should provide access to justice for children, including through “removing barriers for children to initiate proceedings themselves”.

“This could definitely strengthen their hand because now there’s a fully articulated set of guidance that pulls everything together in one place,” said Ann Skelton, chair of the committee and a South African lawyer, adding that she also hoped businesses and policy makers would draw on the document.

Some 16,000 children across more than 100 countries were consulted as part of a broader dialogue during the two-year drafting period for the guidelines. Tânia dos Santos Maia, a 14-year-old from Brazil, said she expected the U.N. document to make children and adolescents more aware of their rights.

The guidance was broadly welcomed, however, some say it does not go far enough. Swedish climate activist Greta Thunberg asked the committee “to be more vigorous and somewhat bolder” during consultations, U.N. committee member Philip Jaffé told Reuters. Thunberg was not immediately available for comment via a spokesperson.

Lawyers representing six young people from Portugal, who are taking 32 countries before the European Court of Human Rights for what they see as government inaction over climate change, said they think it will reinforce their case.

All U.N. countries, barring the United States, have ratified the 1989 child rights convention, which addresses environmental matters but needed updating, given the pace of climate change. The committee’s guidance on the convention is often cited by lawyers, and sometimes by courts in rulings.

Thunberg’s delegation was not alone in calling for more ambition.

“I think this was such a missed opportunity – it’s an exercise in incrementalism instead of taking quantum leap forward,” said Kelly Matheson, deputy director of Global Climate Litigation at Our Children’s Trust which represented youths in a case where a state judge found against the U.S. state of Montana this month.

She said the U.N. body’s guidance limits itself to the 2015 Paris warming target of 1.5 degrees Celsius — a rise she says is already dangerous for children.

Skelton said the U.N. had to balance its actions as some states were already saying it went too far.