WASHINGTON (March 18, 2025) — A new peer-reviewed study published today by the Union of Concerned Scientists (UCS) and partnering researchers in Environmental Research Letters quantifies how historical heat-trapping emissions from the world’s 122 largest fossil fuel producers and cement manufacturers has all-but-guaranteed an additional 10-22 inches (0.26-0.55 m) of global sea level rise by 2300. The study also finds that nearly half of the increase in present-day average surface temperatures and one-third of sea level rise can be linked to these "Carbon Majors.” The analysis identifies how the Carbon Majors’ past emissions are driving current global warming and future sea level rise. It does not include projections based on emissions from other sources, or future emissions from the Carbon Majors, both of which will further exacerbate climate damages.
The research modeled three different scenarios, uncovering what would have happened if industrial fossil fuels had never been developed, were phased out after 1950 when many companies were becoming aware of the impacts of their planet-warming emissions, or after 1990 when international efforts to confront climate change first began and companies like Exxon were deeply involved in campaigns to deceive the public about the reality of the climate crisis.
The new findings underscore how every delay in phasing out fossil fuels burdens future generations who need to adapt to rising seas and recover from loss and damage due to sea level impacts. Emission from the Carbon Majors' products between 1990 and 2020 are responsible for more than half of the projected long-term sea level rise that will occur by 2300.
These impacts will not be felt uniformly. According to earlier research by the study’s lead author, Dr. Shaina Sadai, nations in the Alliance of Small Island States could experience as much as 34% more sea level rise than the global average due to Antarctic Ice Sheet mass loss. The long-term response of sea level rise and disproportionate impacts on communities who minimally produce emissions are a source of climate injustice. Understanding how past emissions from industrial polluters will contribute to future sea level rise is critical as communities seek to hold major polluters accountable for climate impacts.
Below is a statement by Dr. Shaina Sadai, lead author, former UCS Hitz Fellow and current visiting assistant professor at Mount Holyoke College.
“Historical inaction by fossil fuel producers despite early knowledge of their products’ harms has compounded the impacts of climate change. Their enormous profits come at the expense of peoples’ lives and livelihoods around the world. Coastal and island communities who have little to no responsibility for historic emissions are now faced with rising seas that will impact them for centuries to come. This is an enduring climate injustice that must be addressed.
“As we approach long-term average air temperatures exceeding 1.5°C above the preindustrial average, this research shows that this could have been avoided if corporate and world leaders had listened to the science and taken action to protect people and the planet. The alternative timelines we modeled in our research show that phasing out fossil fuels in 1950 or 1990 would put us well below even a single degree Celsius of temperature rise today, sea levels would be lower, and we could have substantially limited the burden on future generations to adapt to rising seas.
“The science is unequivocal: Every fraction of a degree of warming matters, and island and coastal communities have made it clear that every inch of sea level rise matters. Our new research reaffirms the consequences of delaying the phase out of fossil fuels. The best time to phase out fossil fuels was decades ago, but the next best time is now.”
Below is a statement by Dr. Delta Merner, co-author and associate director for the Science Hub for Climate Litigation at UCS.
“This research contributes to the growing body of work that quantifies how fossil fuel producers’ past emissions will harm future generations. Island and coastal communities will bear the disproportionate brunt of the impacts of sea level rise over time, including infrastructure damage, habitat loss, saltwater intrusion, increased flooding, economic burdens and forced displacements.
“Decades of disinformation and a lack of accountability for fossil fuel producers—as well as the high-emitting, wealthy countries like the United States where many are headquartered— has enabled continued climate inaction at odds with clear scientific evidence. This failure to act has all but guaranteed long-term sea level rise, deepening the risks faced by communities with the least resources to adapt.
“Scientific evidence must serve as a foundation for decision making that protects people and the planet. International decisionmakers and the courts have a responsibility to address past, current and future climate injustices posed by the threat of sea level rise directly caused by the historical and planned emissions from fossil fuel producers.”
Additional resources:
- UCS "Tracing Tides" fact sheet on the new study
- UCS blog post on the new study
- UCS blog post on the science behind sea level rise
- UCS blog post on climate accountability lawsuits
- UCS blog post on Carbon Majors
- UCS blog post explaining IPCC climate scenarios
- Influence Map Carbon Majors Report, 2023 update
- 2024 UCS report on U.S. infrastructure jeopardized by sea level rise
- 2017 UCS study on Carbon Majors’ contributions to increased sea level rise and warming
- 2023 UCS study on Carbon Majors’ contributions to increased wildfire risk
- UCS toolkit for scientists seeking to support legal accountability for the fossil fuel industry