Indonesian islanders seek justice, plant mangroves as seas rise

Residents of Pari Island sue Swiss Cement Maker Holcim

Climate change is blamed for higher temperatures and warmer seas

Indonesian coastline is being eroded by mangroves.

By Leo Galuh

The Women's Group of Pari Island is hoping that mangroves will protect its coastline from rising sea levels, tidal flooding, and stronger waves. Mangroves absorb greenhouse gases, which are harmful to the planet.

The sea has changed. "It's hotter and rougher. It scares us," Asmania, a mom of three, said as she dug her hands in the sand below the shallow sea.

Pari Island, near Jakarta's capital, is home to only 1,000 people. However, it is the subject of an important court case that has global significance over the effects of climate change on the island's beaches.

Asmania (who goes by one name) and three other residents of the island sued Holcim, a Swiss cement company, in 2023. They accused it of failing reduce emissions while their island was repeatedly flooded.

According to the Global Cement and Concrete Association, the production of cement contributes approximately 7% of global carbon dioxide (CO2) emission.

The court in Zug, the city where Holcim's headquarters is located, has yet to decide whether or not it will hear the case.

SINKING ISLAND

Indonesia, an archipelago of 81,000 km coastline, is extremely vulnerable to erosion. The sea level has been rising by 4.25 millimetres per year since 1992 and threatens to submerge smaller islands such as Pari.

According to the environmental group Indonesian Forum for the Environment, and Swiss Church Aid (a non-profit working on climate justice), who are supporting the lawsuit against Holcim, about 11% of Pari’s 42 hectares have already been lost to the ocean.

Asmania believes that Holcim's cement plant in Indonesia has contributed to the rising sea level, even though it hasn't operated since 2019.

This is not a matter of distance. "This is global damage caused Holcim's emission," she said. "It is unfair, because we are the ones who suffer from the impact."

Asmania arrived on Pari Island for the first time in 2005, when it was a clear, cool sea rich in life that allowed people to grow seaweed and fish. She first noticed the water warming up in 2010.

She said that the seawater was cool and bluish green, allowing seaweed to grow at a depth around 30 centimetres.

"In 2023, our seaweed harvest failed. "It all melted because of the heat from seawater," Asmania said, showing a seaweed clump with white patches.

Sartono, her husband, said that only seven of 400 groupers released in his farm by him in August were still there two months later.

According to a study in 2025 published in Frontiers in Marine Science, sea surface temperatures in Indonesian water have been steadily rising since 1982. They are warming by 0.19 degrees Celsius (0.34 F) per decade as a result of climate change.

Accountability is a priority

The Cantonal Court of Zug conducted a preliminary hearing on September but has not decided whether or not the case will proceed. Its future is uncertain.

The case, although it may not affect international law, is indicative of a growing trend where communities are testing corporate accountability beyond borders, according to Glenn Wijaya. A Jakarta-based attorney who specializes in mining, renewable energy, and energy projects.

He said that there is a growing momentum in the world whereby people who are affected by climate change, and particularly those companies with major emissions, file lawsuits.

A German court in May rejected the appeal of a Peruvian farm against RWE. He accused RWE, Germany's energy company, for putting his home and livelihood at risk due to climate change. It set a precedent, however, by determining that companies are liable for their emissions.

Mustaghfirin (53), another plaintiff who uses only one name in the Holcim lawsuit, stated that catching fish in recent years has become more difficult due to unpredictable weather and sea currents.

He could catch up to 60 kg per day in the 2000s. Since 2020, his daily catch has been no more than 10kg.

Fishermen depend on nature. He said that if we treat the nature well, she will return the favor.

Mangroves are a great way to prevent erosion, absorb CO2, and provide a breeding ground for crabs, sea cucumbers, and fish.

A report from the World Bank in 2022 states that more than half of Indonesia's total catch is made up of species dependent on mangroves. The report estimated that mangroves are worth between $15,000 and almost $50,000 annually, depending on the amount of carbon they sequester.

Indonesia is home to 20 percent of the mangroves in the world. The vegetation, which looks like upside-down tree root, acts as a barrier to waves, a nursery and carbon sink.

Over time, sediment trapped in the soil can expand coastal areas and create new land. The roots of the mangrove act as natural barriers that absorb up to 90 percent of wave energy.

They hold back sediments that come from seawater and land runoff, stabilizing the coast and preventing erosion, said Fery Kurniawan. He is a lecturer on aquatic resource management in the West Java Province at the Bogor Agricultural Institute.

It can be hard for them to thrive.

Greenpeace activist Jeanny Sirait in Indonesia said that seedlings need to have a minimum of a third above the water surface for photosynthesis.

She said that only five mangroves out of ten are likely to survive because of these natural hazards.

Asmania, despite the challenges, said she would continue to restore mangroves on Rengge Beach in an effort to save the Island.

(source: Reuters)