When Typhoon Haiyan made landfall on November 8, 2013, Joanna Sustento wasn’t all that worried. Tropical storms are common in the Philippines. But this one was different. Water surged to chest level in her family’s house and forced her and six relatives to evacuate. Outside, the water kept rising. Sustento remembers feeling like she was inside a washing machine. The wind was cold as crushed ice. Waves swept her older brother, sister-in-law and nephew away. She saw her dad gasping for air. Currents kept dragging Sustento underwater. Finally she was able to grab a large piece of wood. She tried to pull her mom onto it but realized it was too late. Her mom had drowned. Sustento had to leave her mom’s body to make it to safety. “No words can explain how I felt,” the 25-year-old later recalled.

Haiyan destroyed the city of Tacloban and many of the surrounding communities. It killed over 6,300 people, including Sustento’s mother, father, brother, sister, and nephew. She remembers “crying my eyes out, screaming my heart out.” Susento doesn’t think it was a random tragedy. She blames climate change for intensifying the storm. And she blames 47 of the world’s worst corporate polluters for causing climate change. These companies, Sustento is convinced, are morally responsible for what happened to her family. She wants them held legally responsible as well.

“That’s one myth that the big polluters have been feeding us, that [climate change] is everyone’s fault,” Sustento told me in a Tacloban coffee shop that had been underwater during the typhoon. “We need to go directly to the people who started it.”

Most of the discourse around climate change has to do with either convincing people that it is real, or talking about how to slow it down and mitigate its effects. But a human rights commission in the Philippines is trying to settle once and for all the issue of blame. It will be holding public hearings in the US, Europe, and the Philippines this year is to answer a potentially explosive question: Should the 47 “carbon majors,” the biggest investor-owned greenhouse gas emitters in the world, be held accountable for fatalities and destruction linked to their business model?

Here is some of the evidence the commission may consider: These companies (which include top producers of oil, gas, coal, petrochemicals, and cement) are responsible for almost a quarter of all the greenhouse gases emitted since 1751. An Exxon scientist warned the company back in 1981 that climate change could cause “effects which will indeed be catastrophic—at least for a substantial fraction of the earth’s population.” Exxon, Chevron, BP, Shell, Peabody Energy and other fossil fuel producers spent years denying that global warming was real. And the industry to this day pressures Republican politicians in the US to reject the science.

“As the research shows, they already knew the climate risks [of their business model] but they didn’t do anything about it,” Sustento said.

The Philippines Commission on Human Rights is not a court. It can’t make legal rulings. All it can do is provide an opinion about whether these 47 corporations committed human rights abuses—and map a path to justice for the victims. Yet several of the companies have tried to shut the investigation down. “[We] have made various legal challenges to the Commission’s activity,” a representative of ConocoPhillips acknowledged in 2016. But the Commission on Human Rights is not backing down. “We are determined to proceed,” Commissioner Roberto Cadiz explained to me last December in Quezon City at the investigation’s opening.

Legal observers in Europe and the US are watching closely. Some believe this case has the potential to transform our understanding of climate change from a distant scientific threat for which we are all partially responsible to deadly chaos accelerated by 47 corporations. “Lawyers learn from each other,” John Knox, the United Nations Special Rapporteur on human rights and the environment, told me. “If the Philippines Commission on Human Rights is able to make a persuasive case… then you would expect to see those arguments appearing in other forums.” For companies like Exxon, Chevron, Shell, and BP, it increases the risk of lawsuits and regulations that could cost them trillions of dollars.

The story of this investigation begins on the first day of the 2013 United Nations climate talks in Warsaw, when Yeb Saño, the diplomat heading the Philippines delegation, stood up to deliver a speech to more than 1,000 delegates from around the world. Three days earlier, Typhoon Haiyan, one of the strongest tropical storms ever recorded, had made landfall. It destroyed more than 280,000 homes and left nearly 2 million Filipinos homeless. Saño’s father grew up in Tacloban, the city hit hardest. Family members still lived there, and Saño spent hour after excruciating hour waiting to hear if his brother and other relatives survived. He eventually got news that his brother was safe. But on opening day of the Warsaw negotiations Saño was still unsure about the others. Philippines President Benigno Aquino III had told Saño’s delegation to “show a picture of strength to calm fears.” Yet as he addressed the UN delegates he felt overcome by emotion. “I chose another path,” he told me.

Saño knew that back in Tacloban his brother was pulling dead bodies from the wreckage while tens of thousands of newly homeless Haiyan survivors struggled to find food and water. “I had the choice to… follow what diplomats are supposed to do and be unemotional and impersonal and thank the world for their sympathy,” Saño recalled. Instead, he began to weep. “What my country is going through as a result of this extreme climate event is madness,” Saño told the conference. He said he’d stop eating food until the talks produced meaningful progress. “We can stop this madness,” he said. Saño wiped away tears. He received a standing ovation.

Video of the speech has been viewed more than a million times. His tears had communicated something that decades of high-level bureaucratic meetings and scientific reports could not. “Real lives are at stake,” he said. “Climate change is not just words and numbers and figures.” Saño resigned from his diplomatic position and got hired as head of Greenpeace East Asia. He didn’t see the suffering his family and countless other Filipinos endured during Typhoon Haiyan as an unexplainable disaster. Not only could it be explained, Saño he believed that it could ultimately be traced back to the fossil fuel business model.

Greenpeace and other civil society groups presented their argument in a 2015 petition to the Commission on Human Rights. They pointed to calculations from climate researcher Richard Heede showing Exxon, Chevron, ConocoPhillips, Shell, BP and several dozen other “carbon majors” are responsible for 22 percent of all human carbon emissions. And they cited science linking those emissions to crop failures, rising seas, ocean acidification, and disasters like Haiyan. “Climate change interferes with the enjoyment of our fundamental rights as human beings,” the petition reads. “Hence, we demand accountability of those contributing to [it].”

The Commission on Human Rights reviewed the petition and agreed to hold an inquiry. In doing so it was making history. “This kind of case has been filed before other national human rights institutions but they all rejected it,” Commissioner Cadiz explained. “But [we] said, ‘Alright, we are willing to be the first.’” Reactions from the companies under investigation were varied. Many ignored a request in 2016 to provide input. Some listed their investments in clean technologies. And others—including ConocoPhillips, which made several legal challenges to the commission’s jurisdiction—effectively tried to shut the investigation down.

In a narrow sense, the “carbon majors” have little to worry about—they’re being investigated by an under-funded commission with no binding legal power. But moral questions loom as large as legal ones. Society has not yet reached a consensus on who is responsible for climate change. Do we blame the companies that dig up fossil fuels, the utilities that burn them to make electricity, the people who pump them into their cars? “These are really difficult questions, difficult in the sense that you don’t have a right answer,” said Benoit Mayer, an assistant professor of law at the Chinese University of Hong Kong who writes extensively on climate change. But the Philippines investigation is rejecting ambiguity. Mayer thinks “it can give a very strong signal” about who is morally at fault for global warming. And it provides a grim reminder of the human lives at stake.

Sustento was in shock after the water receded. “Everything was lost,” she told me. She now sees what happened as a violation of human rights. “Our right to a safe environment, because our homes were washed away. Our right to life, because our friends and families lost their lives.” Schools were badly damaged, churches destroyed. People lost “even the mental space to grieve,” she said, “because we needed to prioritize survival.” Tacloban is now physically rebuilt, but psychological damage remains.

The question of who’s to blame for the violations is less obvious. Some people in Tacloban saw Haiyan as god’s punishment for their sins. Sustento quickly rejected that explanation. “Children don’t have sins,” she said. “If it’s god’s punishment, what kind of god is he?” The more she learned about Haiyan, the more she believed that humans were responsible for what happened. Haiyan registered 8.1 on an intensity scale only designed to go up to 8.0, with winds nearly 195 miles per hour. Though it’s difficult to link any one disaster to global warming, scientists who’ve studied Haiyan think warmer and higher seas made the typhoon more destructive. “I really believe it is an effect of climate change,” Sustento said.

But it took several years for her to go from seeing climate change as something everybody is equally at fault for to seeing it as the deadly result of decisions made by fossil fuel executives. Two things helped move her in this direction. The first was her growing involvement in the cause. Before her brother died in Haiyan, he had been close friends with AG Saño, the brother of the diplomat. AG Saño went to the 2015 Paris climate talks and painted a mural of Sustento’s brother, calling it “the face of climate change.” Greenpeace later asked Sustento if she would share her Haiyan story on the group’s website. Last July, she joined a Greenpeace protest against Statoil.

The second thing was the release of hundreds of documents over recent years suggesting Exxon and other oil companies knew internally about the “catastrophic” risks of climate change—including its potential to increase the destructive fury of storms—while publicly discrediting the science. Sustento thinks this strategy is so immoral that she “cannot believe there are really people who exist” capable of executing it. To her this settles the question of responsibility for climate change. “Yes, we all do have a contribution, but it’s not as big as compared to these big polluters who have known of the climate risk for many, many years,” she said.

This narrative is important for Sustento. It means that her family, friends and community didn’t suffer for nothing. It’s given her moral agency during a time of indescribable despair. But is the legal system also willing to accept it? That’s the question at the heart of the Commission on Human Rights investigation. And it’s hard to answer.

“It’s important that the law… recognize that climate change does have these impacts on human rights,” Michael Burger, executive director of the Sabin Center for Climate Change Law at Columbia University, told me. And though the investigation “provides a very powerful storyline to motivate ambition on climate change,” he added, “legally it’s less clear what the end result [will be.]”

It was a muggy December afternoon when I arrived at the Commission on Human Rights headquarters in Quezon City to attend the investigation’s opening. The media presence consisted of just a few local reporters and me. The purpose of the day was to figure out the types of details—including witnesses, exhibits, and timelines—that would allow public hearings to proceed. As Comissioner Cadiz said, “How are we going to navigate this process?” All 47 companies under investigation had been asked to send representatives. But as the conference got started nobody I spoke to was sure which, if any, of the “carbon majors” would actually attend.

I spent most of the afternoon outside, where dozens of Haiyan survivors from Tacloban and the surrounding region had gathered in front of a temporary stage. One by one they got up and told stories. It seemed to be somewhat of a catharsis: Laughter turned to tears turned to anger turned back to laughter. Midway through the day, Sustento took the stage. She spoke mostly in Tagalog. But I could guess what she was saying. On either side of me, men and women wiped their eyes and there was a heavy silence when she paused to check her notes. “Climate change,” Sustento finished in English, “is one of the biggest injustices in human history.”

Not long after, news came that the conference was done. I went inside to a small room where officials were discussing the day and eating plates of spaghetti. I saw Cadiz at the back and asked him if any of the 47 corporations had shown up. Just one, he replied, the cement maker CEMEX. “And they came to question the jurisdiction of the commission,” he said. Cadiz shrugged it off. “We do not have territorial jurisdiction over these companies,” he said, “we can’t award damages against them, but that’s a very narrow view.” The commission will hold hearings across the Philippines in 2018. Top universities in the US and Europe have also offered to host them. An official report is due in early 2019. “It can be a jumping point for further cases brought before any court or jurisdiction,” he explained.

This is just one of many legal proceedings against carbon producers related to climate change. A German court decided last year that a Peruvian farmer’s lawsuit against the coal power giant RWE is admissible. New York, San Francisco, and Oakland are currently suing big oil. Los Angeles is considering it. The number of climate lawsuits in the world has tripled over the past three years. Organizations such as the World Economic Forum are warning “companies can expect to face increasing regulatory risks.” The threat to big oil may be as high as $2.3 trillion.

“In public, the oil majors dismiss what they see as political theatre, but there is growing concern that scientific work linking hydrocarbons to climate change and climate change to extreme weather could produce judgments against the industry as a whole and perhaps individual groups.” wrote Nick Butler, a Financial Times columnist who spent 29 years working at BP.

Yet none of the 47 corporations participated in the Philippines investigation. I went outside to find Sustento. I wanted to know how she felt about the companies ignoring the case. “At first I thought it’s kind of bad news because it means that they don’t care about the people here or maybe they think it’s just a joke, or they’re underestimating what we can do,” she said. But spending the day with Haiyan survivors had been invigorating. “I truly believe that the stories we heard today and the stories of my community… can make people realize, S hit, these things could also happen to us,” she explained. “And then maybe they’ll be moved to do something about it.”

She smiled: “I think what happened today is good news.”

Geoff Dembicki is the author of Are We Screwed? How a New Generation Is Fighting to Survive Climate Change_. Follow him on_ Twitter.