Researchers have for the first time tied a group of the world’s largest fossil fuel companies, including ExxonMobil, and their products to specific increases in greenhouse gases, global warming and sea level rise. A study published Thursday in the journal Climatic Change concludes that since 1880, 90 of the largest carbon producers are responsible for up to 50 percent of global temperature rise, 57 percent of the increase in carbon dioxide in the atmosphere and between 26 and 32 percent of global sea level rise.
The research could open the door for those who have suffered losses due to climate change to sue major oil companies for damages. The study also links each individual company to its percentage impact on climate change.
“This study could inform approaches of juries and judges who are looking to monetize damages,” said study lead author Brenda Ekwurzel, a climate scientist at the Union of Concerned Scientists.
Three suits have already been filed against a group of fossil fuel companies by three California communities attempting to hold them accountable for damages caused by climate change. The new research helps assign percentages of blame to those companies.
“This is a very important study that further confirms key elements of the lawsuits against many of these fossil fuel companies,” said Vic Sher, partner in Sher Edling, the law firm representing the three California communities. “The science is clear that these companies have caused a substantial portion of the sea level rise that is damaging San Mateo County, Marin County, the City of Imperial Beach, and communities like them around the country.”
The research—conducted by a team of scientists from UCS, the Climate Accountability Institute and Oxford University—estimates each major oil company’s greenhouse gas emissions dating back to 1880 and calculates how much those emissions contributed to climate change.
The paper breaks those results into two separate categories: individual energy companies’ overall contributions to climate change between 1880 and 2010 and their contributions to climate change between 1980 and 2010 — a period during which the firms’ own science showed their products cause global warming.
In the century prior to 1980, companies may not have been aware of the harm their products cause, Ekwurzel said. After 1980, the firms had sufficient scientific data showing carbon dioxide from burning the fossil fuel they produce was harmful.
Investigations by journalists as well as scholarly research concluded that ExxonMobil knew decades ago that their products are harmful to the climate and that instead of taking action to mitigate the harm, the company misled the public and cast doubt on climate science. Exxon did not respond to requests for comment.
“Once it became clear no later than the 1960s that continuing CO2 emissions would progressively undermine the climate, the major carbon producers could see that they were marketing harmful products,” said Henry Shue, a professor emeritus of politics and international relations at Oxford University, wrote in a commentary published alongside the study.
He said responsible fossil fuel companies should have either developed methods to capture and store carbon emissions associated with their products or substituted them with non-carbon-based forms of energy.
“If ExxonMobil and similar companies had acted on their own scientists’ research about the risk of their product, climate change would be far more manageable and less costly today,” Ekwurzel said.
The study finds that state-owned Saudi Aramco of Saudi Arabia and Gazprom of Russia contributed more to global warming than any other company since 1980. But Exxon, BP, Chevron, Shell, and Peabody Energy are the world’s largest investor-owned companies that contributed to global warming and sea level rise in that time.
Exxon contributed more climate pollution than any investor-owned company. It and its predecessor companies alone are responsible for nearly 1.5 percent of the historical rise in global atmospheric carbon dioxide concentrations between 1980 and 2010 and more than 2.75 percent since 1880, the study said. The company’s emissions have contributed more than 1 percent to the rise in global average surface temperature since 1980, and about 0.5 percent to sea level rise during that period.
Overall, Saudi Aramco has contributed more to the rise of atmospheric carbon dioxide since 1880 than any other company — more than 3 percent. Chevron is the leading contributor to both the historical rise in surface temperatures and sea levels since 1880 — just more than 2.75 percent on both counts.
The research builds upon 2013 research by Climate Accountability Institute founder Richard Heede, which quantified the total historical carbon dioxide and methane emissions of the top 90 fossil fuel companies and other carbon producers.
Kevin Trenberth, a climatologist at the National Center for Atmospheric Research in Boulder, Colo., said the study makes a “reasonable guess” about each fossil fuel company’s responsibility for global warming.
But he said the study is flawed because the researchers did not test the climate model they used on independent data. The model may also be overly simplistic, leading to errors, he said.
“For example, it uses global mean surface temperature but has no hydrological cycle, no land-versus-ocean, no Arctic amplification and no validation,” Trenberth said. “It does not provide any information about how good any of the relationships are that the model is based on and how stable they are over time.”
Legal experts say the study opens the door to legal liability for oil companies and possibly tobacco-style lawsuits, which found that tobacco companies misled the public to cast doubt on the dangers of cigarettes.
“Litigants will still face a number of hurdles to win a tobacco-style climate lawsuit, but this study helps considerably to quantify shares of causal responsibility,” said Douglas Kysar, a Yale Law School professor whose research focuses on product liability and climate change law.
“The need to assign liability has increased significantly in recent years as we have learned more about the fossil fuel industry’s decision to ignore its own internal evidence regarding the catastrophic threats posed by climate change and to intentionally mislead the public and policymakers regarding those threats,” he said.
Mary Wood, a natural resources law professor at the University of Oregon Law School, said the study is a major leap forward in laying the scientific groundwork for a liability suit against fossil fuel companies for damages from climate change and sea level rise.
“It takes on the task of translating emissions into actual damage to these vital planetary systems,” she said.
But Michael Burger, executive director of the Sabin Center for Climate Change Law at Columbia University, warned that the study itself does not determine any company’s legal liability.
“The study offers another piece of scientific evidence that supports attributing some specific portions of climate change impacts to a set of some 90 fossil fuel production companies,” Burger said. “The body of literature on attribution science is large and growing. The new UCS study makes a contribution to that body of literature, but it is not determinative in and of itself of any company’s or companies’ liability.”