Sitting near a wall of stacked rocks, fisherman Mustagfirin looks out to sea from the tiny Indonesian island of Pari, wondering whether his home will exist for much longer.

His battered wooden boat is anchored just offshore, where trees and statues that were once on the beach now sit partially submerged about 40 kilometres (25 miles) north of the capital Jakarta.

“I am very saddened and terrified knowing in the next 10 or 20 years Pari island might disappear,” the 52-year-old told AFP.

Environmentalists have said most of the 42-hectare (103-acre) island could sink by 2050 because of rising sea levels.

The island’s residents are seeking justice, and last month sued Swiss cement giant Holcim over its emissions. They allege the world’s largest cement firm is responsible for climate-related loss and damages in a case that could be a landmark for plaintiffs from developing countries who take on industrial giants.

Environmental litigation against governments and fossil fuel firms has surged in recent years – but this is the first case filed by Indonesians against a foreign company for climate-related damage.

It is also the first instance of a Swiss company being sued for its alleged role in climate change.

“Winning this case might spark the spirit for other islanders affected by climate change to demand justice,” said Puspa Dewy, an environmentalist at Indonesian NGO Walhi.

That spirit of activism can be seen across the picturesque, flat island where posters and graffiti of “Save Pulau Pari” and “Climate Justice Now” are plastered.

• Concrete action -

Residents say saltwater floods as high as 1.3 metres (4.2 feet) have surged since 2019, battering homes and damaging livelihoods.

The floods used to happen twice a year but now hit the island more than a dozen times annually, they say. Swiss Church Aid (HEKS), an NGO helping the islanders, said Pari has lost 11 percent of its surface area in the past 11 years.

“Where will we live? My ancestors, my parents, my children, and even my grandchildren were all born here,” said Mustagfirin, who like many Indonesians goes by one name.

He is one of the four residents calling for Holcim to reduce its emissions in the civil complaint filed in Zug, where the firm is headquartered.

Another is mother-of-three Asmania, who lost her seaweed farm to flooding and worries about her fisherman husband who trawls the sea in extreme weather for ever-smaller catches.

“We want to send a message to other corporations: please stop thinking only about profits,” the 39-year-old said.

They are claiming 3,600 Swiss francs ($3,800) each for damages and protection measures such as mangroves.

A resolution could take four years if it reaches Switzerland’s highest court, according to HEKS. The islanders took aim at Holcim because no one has acted against a major cement company before, environmentalist Dewy said.

Cement manufacturing accounts for about eight percent of global CO2 emissions.

Last year, representatives for the islanders met with Holcim in a mediation process that was not fruitful, prompting the plaintiffs to file their lawsuit.

Holcim, which in 2019 sold its Indonesian operations to a local concrete firm, told AFP it places importance on climate but disagreed with the islanders.

“We do not believe that court cases focused on single companies are an effective mechanism to tackle the global complexity of climate action,” it said.

• ‘Lose our earnings’ -

Pari is dependent on fishing and the tourists who swarm it for quick getaways from the crowded and heavily polluted capital.

Homestays and souvenir shops can be seen across the island of 1,500 people, but rising tidal floods mean more booking cancellations.

“When the flood comes, we lose our earnings. It adds to our suffering,” resident Edi Mulyono said.

His frustrations motivated him to join the lawsuit, hoping the case would send a message to other corporations that they should act more responsibly.

“If Holcim takes responsibility, other big corporations will start to think that they are not the only ones living on this earth,” the 37-year-old said.

At the beachfront home of welder Arif Pujianto, his motorbike had rusted from saltwater and panels on his wooden house were rotting.

“I live in worry. I fear that when I am asleep, the water will suddenly rise,” said plaintiff Pujianto, showing AFP a video of his wife standing in their flooded kitchen.

Mustagfirin and his fellow fishermen regularly take their boats out to plant mangroves in a desperate attempt to slow erosion.

The islanders also create meagre obstacles to the tides, such as making piles of rocks to stymy floods. But they believe legal barriers may offer their biggest hope.

“Please reduce your emissions so you can help save us,” he said.

“Don’t wait until it’s too late. Don’t wait until our island sinks and we disappear.”