MANILA - Petitioners in a landmark human rights inquiry in the Philippines this week spoke of widespread and long-term harm caused by wild weather linked to climate change.

The case is being watched closely. The petitioners accuse global oil, mining and cement companies of human rights violations by playing a role in driving climate change. The inquiry joins a growing list of legal cases around the globe pressuring faster government action to fight climate change and targeting big energy firms, which are among some of the world's top polluters of greenhouse gases blamed for heating up the planet.

The Philippines is highly vulnerable to climate change impacts, such as extreme storms, drought and rising sea levels. Farming and fishing communities are disappearing because of repeated extreme weather events that wipe out entire crops and fishing grounds, the petitioners warned during the hearings, which ended on Tuesday (March 27).

Low-lying parts of the country are particularly vulnerable to storms. Scientists say a warming atmosphere and ocean are fuelling more powerful storms, like Typhoon Haiyan, which killed more than 6,000 people in November 2013 and caused more than US$4 billion in damage to homes, infrastructure and crops.

Many of the country's more than 100 million people are poor and are particularly vulnerable to worsening floods and storms.

"No one wants to take up farming anymore," said Mr Felix Pascua, spokesman for a farmers' group in the central Philippines.

He said the average age of Filipino farmers now is 53. "That is the impact on us of climate change. No parents want to see their children grow up to be farmers."

Ms Nerisa Libao still remembers two long dry spells in 1987 and 1991 that decimated the calamansi trade in the small island of Alabat, in Quezon province, east of the capital Manila.

"Before that, in the 1970s, Alabat was a 'calamansi basket'. Our calamansis were known all over the Philippines. Then the drought hit. It killed all the citrus trees. We have not recovered from that. Somehow, the extreme heat made pests more resistant, and the calamansis much drier," said Ms Libao.

Mr Pascua and Ms Libao testified at the two-day "national inquiry on climate change" conducted by the Philippine Commission on Human Rights (CHR), an independent body set up by the government.

The commission agreed in 2015 to hold hearings on a petition claiming that some 50 firms infringe on Filipinos' rights to life, food, water, sanitation and adequate housing, through the growing impact of global warming.

Oil giants Chevron, Shell, BP and ExxonMobil, and miners Rio Tinto and Glencore are among the "carbon majors" cited in the petition.

The inquiry is the first time a government agency anywhere in the world has accepted, and acted on, a request for investigation of the environmental responsibility of companies that sell or are heavy users of fossil fuels, said Ms Zelda Soriano, a lawyer with Greenpeace South-east Asia.

The CHR can only make recommendations to Philippine legislators and the business world, and has no enforcement powers.

PRECEDENT

But Ms Soriano said the inquiry would set a precedent, and the commission's resolution and proposed measures would add weight "to every existing and future climate-change litigation case in any part of the world, no matter the outcome".

Ms Lisa Hamilton, director at the Centre for International Environmental Law (CIEL) and one of the expert witnesses, said the petition "is both a moral and legal plea to address climate change as one of the greatest threats to human rights of our time".

The Philippines' complaint complements a global upsurge in legal challenges seeking redress for climate-change impacts. Legal filings in countries from Germany to Pakistan and the Netherlands aim to force faster action to tackle climate change and its impact, or claim damages from energy firms.

"We can no longer ignore the impact of significant changes in global temperatures and rising sea levels on people's lives. This is a matter already described by former US vice-president Al Gore as an 'inconvenient truth', a truth with devastating consequences suffered by nations across the world such as the Philippines," CHR chair Jose Luis Martin Gascon said in his opening remarks.

The Philippines, with 70 per cent of its cities and towns in coastal areas, is the nation third-most exposed and vulnerable to climate change, after Vanuatu and Tonga, said Dr Rosalina de Guzman, chief of the climate data section of the local weather bureau.

She said the sea level rise on the Pacific side of the Philippines, at 4.5mm to 5mm each year, has been higher than the global average of 2.8mm to 3mm.

Dr De Guzman said unless global greenhouse gas emissions from industry, transport and agriculture are capped through policies such as shifting to renewable energy, the Philippines could expect more tropical cyclones supercharged by climate change.

Dr Victorio Molina, a public health expert with the University of the Philippines, said climate change is also leading to a public health emergency.

He said higher rainfall is causing a rise in mosquito-borne diseases as zika, dengue and malaria. Extreme heat, meanwhile, is leading to more cases of cardiovascular illnesses and heat stroke.

Ms Hamilton, at CIEL, testified to a pattern of deception pursued by the "carbon majors" to downplay harm caused by climate change.

"Industry experts had knowledge, and they had the ability to avoid it, but they failed to do so," she said.

She added that international laws and norms require states like the Philippines "to protect, respect and fulfil human rights".

"The narrative being described is you have the carbon majors committing and continuing to commit human rights abuses… We know their activities contribute to climate change significantly. We understand that climate change threatens access to food, water, among many other human rights. States like the Philippines have an obligation to protect their citizens," said Ms Hamilton.