The case is part of a wider international movement seeking to assign responsibility to major companies for the climate damage hurting the livelihoods of millions of people, especially in the Global South.

Four residents of Pari have filed suit against the world's largest cement firm, demanding that, as a major emitter of carbon dioxide (CO2), it provide compensation for the damages wrought by climate change and help fund protection measures on the island like planting mangroves.

The hearing to determine whether or not the court will consider the complaint will open at 8:30 am (0630 GMT) on Wednesday in Zug, where the firm is headquartered.

Two of the four plaintiffs have made the trip to Switzerland to attend the hearing.

It is unclear how quickly the court will render its decision.

Holcim insists it is "deeply committed to taking action on climate", but maintains that "the question of who is allowed to emit how much CO2" should be "a matter for the legislature and not a question for a civil court".

Environmentalists highlight that cement production is a significant contributor to global CO2 emissions, and allege that Holcim figures among the 100 largest corporate CO2 emitters.

- 'Inspirational' -

The suit maintains that the company thus bears significant responsibility for climate-related loss and damages, in a case that could be a milestone for plaintiffs from developing countries who take on industrial giants.

"I hope the case will become inspirational... for climate victims" around the world, plaintiff Asmania told reporters in Switzerland last week.

Environmentalists have said 11 percent of the 42-hectare (104-acre) island of Pari has already disappeared in recent years and could be underwater by 2050 due to rising sea levels.

The islanders say saltwater floods have at the same time surged in scale and frequency, battering homes and damaging livelihoods.

Environmental litigation against governments and fossil fuel firms seen as responsible for the greatest CO2 emissions has surged in recent years, but the case marks the first such action against a major cement company.

It is also the first filed by Indonesians against a foreign company for climate-related damage, and the first instance of a Swiss company being sued for its alleged role in such damage.

The four plaintiffs in the case are seeking 3,600 Swiss francs ($4,500) each from Holcim for damages and protection measures such as planting mangroves and constructing breakwater barriers.

Swiss Church Aid (HEKS), an NGO helping the islanders, stressed that the amount was only equivalent to 0.42 percent of the actual costs -- in line with estimates that Holcim is responsible for 0.42 percent of global industrial CO2 emissions since 1750.

In addition, the plaintiffs are demanding a 43 percent reduction in Holcim's greenhouse gas emissions by 2030 and a 69 percent reduction by 2040.

The plaintiffs "hope the court will declare itself competent to examine their demand for a company that shares responsibility for the climate crisis to pay for damages suffered by the island", Yvan Maillard-Ardenti, head of climate justice at HEKS, told AFP.