“I grew up a little bit like Heidi,” she told Al Jazeera, referring to the children’s fictional character. “I was really herding goats up there.”

Over the years, those Alpine hulks of rock and ice have been melting rapidly – one called Pizol has lost at least 80 percent of its volume since 2006 alone as global temperatures have steadily risen.

Stern could sense something was wrong, but did not start connecting the dots until she went on a study trip to Zimbabwe in the early 1990s, where she became aware that rainfall was declining.

Climate change was a matter of growing public interest at the time because of an important international conference in Rio de Janeiro – the United Nations Conference on Environment and Development, or the so-called Earth Summit.

Although most of her professional life was spent as a cultural anthropologist, Stern decided to get involved in environmental advocacy when she returned to Switzerland.

She worked in a green finance start-up by day and was immersed in the peace, feminist and anti-nuclear movements in her spare time.

At 70, she retired, and that only gave her more time for campaigning.

Stern was involved in anti-fracking groups, where she felt warmly welcomed by young activists.

“They treated me like a senior citizen – not in the sense of ‘Ahh, do you have email?’ but actually as a fully competent person.”

But when she joined an association of older Swiss women called the KlimaSeniorinnen, which means Swiss Climate Seniors, she was thrilled to meet people of her own age with similar values.

“I thought they were absolutely great. They might be frail, some of them, in their body, but so fit in their head and so committed to something beyond themselves,” she said.

At the time, the KlimaSeniorinnen had filed a lawsuit against the Swiss government, accusing it of breaching their human rights by not doing enough to combat global climate change by cutting domestic carbon emissions.

The group focuses on climate campaigning. Its 2,038 members are bringing the case, all of whom are aged above 64, including four women over 80.

“It was a revelation to me that you could actually take our state to court for not keeping its word,” said Stern. “We had signed the Paris Agreement but here we were on a path to 3°C of global warming. I have been saying the same thing for the last 35 years but very little changed. Maybe when you take somebody to court it puts a different kind of pressure.”

Having failed to get the Swiss courts to consider their arguments, the KlimaSenniorinnen escalated their case to the European Court of Human Rights.

And at the end of March, Stern and other members of the association’s board will be taking the short train journey from Switzerland to Strasbourg in France, where their legal team, supported by Greenpeace Switzerland, will finally lay out their concerns at a public hearing.

Climate change litigation around the world is growing, but this will be the first such lawsuit heard before the influential European court.

The KlimaSeniorinnen women have half a day to make their complex case in front of the court, and have submitted a dossier of scientific evidence outlining the effects of climate change on people’s health – showing why older people and women are particularly vulnerable.

Delta Merner, who leads the Science Hub for Climate Litigation at the Union of Concerned Scientists in the United States, said the research clearly shows that increased heat from climate change poses a growing danger to human health and “action is needed now to dramatically reduce emissions to prevent increased and foreseeable impacts”.

While Switzerland has targets to cut national emissions, the KlimaSeniorinnen argue these are too weak and want Bern to take much stronger action, especially over the next decade.

In court, their legal team will argue that Switzerland has breached articles two and eight of the European Convention on Human Rights, which protect the right to life and the right to respect for private and family life.

“It’s not only a negative obligation that the state has to refrain from infringing human rights,” says Cordelia Bähr, a lawyer at Zurich-based law firm Ettwein who is representing the KlimaSeniorinnen, “but also a positive obligation to protect human rights.”

Lawyers will also refer to a swath of recent judgements in the Netherlands, Germany and France where courts ruled that governments were not doing enough to cut emissions and ordered them to take swifter action.

“If the European Court of Human Rights would say that there is no violation of human rights, it would also then say that the domestic court decisions in these cases were wrong, and what kind of signal would that send?” said Bähr.

In its response to the lawsuit, Switzerland does not deny that climate change is real and can affect human health.

But it argues that its emissions cannot be directly linked to the health of older women, and maintains that its existing targets are sufficient. Climate change action, it says, is ultimately a matter for politicians to deal with.

Whether the case succeeds will be down to a panel of 17 senior judges, who will also hear another climate change case on the same day, against the government of France.

In that case, Damien Carême, the former mayor of Grande-Synthe in France, argues that the French authorities have failed to do all they can to cut emissions – breaching his human rights.

“The scientific connection between climate change and increased heatwaves is very robust, but I don’t think the impacts of climate change are really on trial here,” said Merner.

“Governments need to understand that they can and must act now … to reduce emissions of greenhouse gases.”

The Pizol glacier under whose shadow Stern played as a little girl is now almost entirely gone, and a funeral service was held a few years ago to mourn it.

But although she admits being involved in an expensive and uncertain lawsuit is “not a Sunday picnic”, Stern is pleased to have her day in court.

“I feel wonderful that it is finally happening. It’s the first time Strasbourg is deciding ‘Is there a link between climate change and human rights?’. For me, it feels like really a historic moment.”

At the time of publishing, Swiss authorities had not responded to Al Jazeera’s request for comment.