One of their lawyers says there have been “extremely positive” signals from the court so far, ahead of the hearing next month.
Dismayed at what they see as government inaction over climate change, six young people from Portugal are taking 32 European countries to court.
A month away from being heard by the European Court of Human Rights (ECHR), they hope their legal battle will inspire others to demand environmental justice worldwide.
The case - filed in September 2020 against the 27 EU member states as well Britain, Switzerland, Norway, Russia and Turkey - seeks a legally binding decision that would force the governments to act against climate change.
It is one of the first such cases to be heard before the court, where citizens say inaction has violated their human rights. It could result in orders for governments to cut carbon dioxide emissions faster than currently planned.
"We just want them [governments] to stick to the treaties and do what they promised they would do," says 15-year-old André Oliveira, one of the six applicants. He points to the 2015 Paris Agreement on cutting emissions to limit global warming to 2 degrees Celsius and aim for 1.5C.
Current policies would fail to meet either goal.
What case do the Portuguese youth have?
Extreme weather has caused havoc in many countries around the world over the past several months, with record temperatures sparking wildfires, water shortages and a rise in heat-related hospital admissions.
With the support of the UK-based Global Legal Action Network (GLAN), the Portuguese applicants argue climate change threatens their rights to life, privacy, mental health and other matters.
Oliveira, who will soon start high school and loves the outdoors, says many in his generation do not know if they want to have children because of climate change, and that he often cannot play outside due to sweltering heat.
His sister, 18-year-old Sofia, says she has suffered from eco-anxiety: "When I found out what was happening... and seeing it was starting to get worse, it really upset me."
Portugal’s wildfires were an “eye-opener” for the young claimants
Clinical psychologist Elizabeth Marks, a specialist on climate distress, said a global survey found that over half of young people feel "sad, afraid, angry, powerless, helpless and guilty" due to climate change and a lack of action to tackle it.
"They feel like they are being let down - repeatedly - by the people that should be helping them and protecting them," Marks said.
Case applicant Claudia Duarte, 24, from Portugal's Leiria region where two wildfires killed over 100 people in 2017, said they were an "eye-opener" on the consequences of climate change.
Her 11-year-old sister had suffered from anxiety after the fires. "It's hard to see children suffering with anxiety for something that they have no control over," said Duarte, who is a nurse.
How likely is the climate court case to succeed?
One of the applicants' lawyers, Gerry Liston from GLAN, believes their chances of success are high as "all the signals so far from the court have been extremely positive", including its fast-tracking of the case as an urgent and important matter.
He acknowledged that "taking on the legal teams of over 30 very well-resourced countries" would not be easy, but said an "explosion of climate cases" occurring in Europe and beyond should eventually force governments to act.
Asked if the ECHR would be able to ensure all countries complied with its decision in case the applicants won their case, Liston said the verdict the legal team was hoping for would be enforced at national levels.
"The judgment we seek would give national courts a roadmap for compelling governments in Europe to act in this way."
Catarina Mota, 22 and also from Leiria, hopes the case will inspire others: "It's not just a case for the six of us...If we can impact and inspire people, we are already doing something for a better world."
The hearing is scheduled for 27 September.