Study Finds Top Fossil Fuel Producers' Emissions Responsible for as Much as Half of Global Surface Temperature Increase, Roughly 30 Percent of Global Sea Level Rise

A first-of-its-kind study published today in the scientific journal Climatic Change links global climate changes to the product-related emissions of specific fossil fuel producers, including ExxonMobil and Chevron. Focusing on the largest gas, oil and coal producers and cement manufacturers, the study calculated the amount of sea level rise and global temperature increase resulting from the carbon dioxide and methane emissions from their products as well as their extraction and production processes.

The study quantified climate change impacts of each company's carbon and methane emissions during two time periods: 1880 to 2010 and 1980 to 2010. By 1980, investor-owned fossil fuel companies were aware of the threat posed by their products and could have taken steps to reduce their risks and share them with their shareholders and the general public.

"We've known for a long time that fossil fuels are the largest contributor to climate change," said Brenda Ekwurzel, lead author and director of climate science at the Union of Concerned Scientists (UCS). "What's new here is that we've verified just how much specific companies' products have caused the Earth to warm and the seas to rise."

The study builds on a landmark 2014 study by Richard Heede of the Climate Accountability Institute, one of the co-authors of the study published today. Heede's study, which also was published in Climatic Change, determined the amount of carbon dioxide and methane emissions that resulted from the burning of products sold by the 90 largest investor- and state-owned fossil fuel companies and cement manufacturers.

Ekwurzel and her co-authors inputted Heede's 2014 data into a simple, well-established climate model that captures how the concentration of carbon emissions increases in the atmosphere, trapping heat and driving up global surface temperature and sea level. The model allowed Ekwurzel et al. to ascertain what happens when natural and human contributions to climate change, including those linked to the companies' products, are included or excluded.

The study found that:

• Emissions traced to the 90 largest carbon producers contributed approximately 57 percent of the observed rise in atmospheric carbon dioxide, nearly 50 percent of the rise in global average temperature, and around 30 percent of global sea level rise since 1880.
• Emissions linked to 50 investor-owned carbon producers, including BP, Chevron, ConocoPhillips, ExxonMobil, Peabody, Shell and Total, were responsible for roughly 16 percent of the global average temperature increase from 1880 to 2010, and around 11 percent of the global sea level rise during the same time frame.
• Emissions tied to the same 50 companies from 1980 to 2010, a time when fossil fuel companies were aware their products were causing global warming, contributed approximately 10 percent of the global average temperature increase and about 4 percent sea level rise since 1880.
• Emissions traced to 31 majority state-owned companies, including Coal India, Gazprom, Kuwait Petroleum, Pemex, Petroleos de Venezuela, National Iranian Oil Company and Saudi Aramco, were responsible for about 15 percent of the global temperature increase and approximately 7 percent of the sea level rise between 1880 and 2010.

"Until a decade or two ago, no corporation could be held accountable for the consequences of their products' emissions because we simply didn't know enough about what their impacts were," said Myles Allen, a study co-author and professor of geosystem science at the University of Oxford in England. "This study provides a framework for linking fossil fuel companies' product-related emissions to a range of impacts, including increases in ocean acidification and deaths caused by heat waves, wildfires and other extreme weather-related events. We hope that the results of this study will inform policy and civil society debates over how best to hold major carbon producers accountable for their contributions to the problem."

The question of who is responsible for climate change and who should pay for its related costs has taken on growing urgency as climate impacts worsen and become costlier. In New York City alone, officials estimate that it will cost more than $19 billion to adapt to climate change. Globally, adaptation cost projections are equally astronomical. The U.N. Environment Programme estimates that developing countries will need $140 billion to $300 billion annually by 2030 and $280 billion to $500 billion annually by 2050 to adapt.

The debate over responsibility for climate mitigation and adaptation has long focused on the "common but differentiated responsibilities" of nations, a framework used for the Paris climate negotiations. Attention has increasingly turned to non-state actors, particularly the major fossil fuel producers.

"At the start of the Industrial Revolution, very few people understood that carbon dioxide emissions progressively undermine the stability of the climate as they accumulate in the atmosphere, so there was nothing blameworthy about selling fossil fuels to those who wanted to buy them," said Henry Shue, professor of politics and international relations at the University of Oxford and author of a commentary on the ethical implications of the Ekwurzel et al. paper that was published simultaneously in Climatic Change. "But circumstances have changed radically in light of evidence that a number of investor-owned companies have long understood the harm of their products, yet carried out a decades-long campaign to sow doubts about those harms in order to ensure fossil fuels would remain central to global energy production. Companies knowingly violated the most basic moral principle of 'do no harm,' and now they must remedy the harm they caused by paying damages and their proportion of adaptation costs."

Had ExxonMobil, for example, acted on its own scientists' research about the risks of its products, climate change likely would be far more manageable today.

"Fossil fuel companies could have taken any number of steps, such as investing in clean energy or carbon capture and storage, but many chose instead to spend millions of dollars to try to deceive the public about climate science to block sensible limits on carbon emissions," said Peter Frumhoff, a study co-author and director of science and policy at UCS. "Taxpayers, especially those living in vulnerable coastal communities, should not have to bear the high costs of these companies' irresponsible decisions by themselves."

Ekwurzel et al.'s study may inform approaches for juries and judges to calculate damages in such lawsuits as ones filed by two California counties and the city of Imperial Beach in July against 37 oil, gas and coal companies, claiming they should pay for damages from sea level rise. Likewise, the study should bolster investor campaigns to force fossil fuel companies to disclose their legal vulnerabilities and the risks that climate change poses to their finances and material assets.