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The smokestacks can stop. The oil wells can close. But the warming will persist for decades.
A new study suggests that carbon dioxide released by the world’s biggest fossil-fuel and cement producers will continue keeping the planet warmer for centuries, even in a future in which humanity sharply cuts emissions. Researchers estimate that historical emissions linked to 178 “Carbon Majors” were responsible for about 0.66° Celsius of warming by 2025. In their lowest-emissions scenario, roughly 0.45° of that warming was still present in the year 2500.
“We know that fossil fuel emissions have caused a lot of warming, and we’re seeing the impacts of that, but the question is: How long does that warming last into the future?” Dargan Frierson, a climate scientist at the University of Washington and lead author of the study, said in a statement.
The answer, according to the researchers, is a very long time.
Some Damage Is Done
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Frierson and co-author Lauren Henrie used the FaIR climate model to run Earth’s climate forward to 2500. They compared four future emissions pathways with counterfactual versions in which carbon dioxide and methane emissions tied to the Carbon Majors from 1854 through 2024 had never occurred.
Those 178 producers include private companies, state-owned corporations, and nation-state producers. The Carbon Majors database counts emissions from their own operations as well as those produced when customers burn the fuels they extracted and sold.
Their historical emissions totaled about 1.29 trillion metric tons of CO2 in the researchers’ calculations—one trillion is a number the human mind cannot intuitively grasp, so for reference, 1 trillion seconds equals 31,688 years; let that sink in. In 2025, the simulations attributed about 80 parts per million of atmospheric CO2 to them. Natural sinks such as oceans and vegetation had absorbed more than half of the emitted carbon, but the other half could persist for centuries or longer.
Attribution science has increasingly connected warming not merely to extreme events but to specific emitters. A 2025 Nature study examined 213 heat waves from 2000 to 2023 and found that Carbon Major emissions contributed about half of the climate-driven increase in their intensity.
Calculable Warming
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One of the new study’s more counterintuitive findings appears when the researchers compare different futures.
In the low-emissions pathway, historical Carbon Major emissions still account for about 0.45° Celsius of warming in 2500. In the highest-emissions pathway, the figure is about 0.31°, but overall warming is much higher. That does not mean continued fossil-fuel use reduces their impact.
Instead, the physics of CO2 is nonlinear. Adding a given amount has a greater heating effect when the background concentration is lower. In a heavily polluted future, the historical contribution sits atop an atmosphere already loaded with far more CO2. In a cleaner future, its contribution to the remaining warming becomes more pronounced.
There are some important caveats. FaIR is a simplified climate model, and the authors say its results become less reliable under the most extreme emissions scenarios. The study also only removes Carbon Major emissions through 2024, even though those companies are still producing fossil fuels. That means the estimates likely understate their total future contribution to warming.
“The amount of warming is calculable and relatively independent of future emissions,” Frierson said. “If there are legal decisions about accountability, the responsibility is not just now, it will continue for many many years into the future.”
The study was published in the journal PLOS Climate.
