Legacy Emissions from Carbon Majors Will Keep Warming Earth for Centuries

When a burst pipe floods a house, assigning blame is straightforward: someone left the faucet running, and the damage can be traced directly back to that act. Climate disasters are far messier. A heat wave, a catastrophic flood or a record-breaking hurricane emerges from a tangle of natural variability and human influence, and for decades the legal and moral question of who caused what remained frustratingly opaque. That opacity is now dissolving. A new study from the University of Washington, published Sept. 23 in the journal PLOS Climate, demonstrates that past emissions from the world’s largest fossil fuel and cement producers will continue to warm the planet and raise the odds of extreme weather for decades, and in some respects for centuries, into the future. The finding transforms climate accountability from a question about what has already happened into a question about what is still to come.

The research focuses on the so-called carbon majors, a term used by researchers and activists to describe the 178 leading oil, gas, coal and cement companies whose products and operations have released the overwhelming majority of industrial-era greenhouse gases. Together, these entities have emitted more than a trillion tons of carbon dioxide, a staggering quantity whose atmospheric consequences do not simply vanish when the smoke clears. Carbon dioxide is a long-lived gas, and a substantial fraction of every ton released will remain aloft, trapping heat, for millennia. The study’s central insight is that this persistence creates a long tail of responsibility: the warming attributable to carbon majors is largely locked in, calculable, and relatively independent of what humanity chooses to do next.

To quantify that legacy, the research team turned to the Finite Amplitude Impulse Response model, commonly known as FaIR, a reduced-complexity climate model widely used to simulate how emissions translate into atmospheric concentrations, radiative forcing and global temperature change. The researchers ran simulations of the global climate all the way through the year 2500, exploring both low and higher emissions scenarios. Crucially, they ran each scenario twice: once with the historical emissions of the carbon majors included through 2024, and once with those emissions removed. The difference between the paired runs isolates the temperature signal that can be attributed specifically to the top producers, allowing the team to track how that signal evolves across a wide range of possible futures.

The results reveal a striking asymmetry. In a future where greenhouse gas emissions are sharply limited, the carbon majors account for a larger percentage of the total warming above preindustrial levels, because their historical emissions dominate a smaller overall budget. In higher emissions scenarios, where fossil fuel burning continues unabated and the planet becomes dramatically warmer, future emissions cause a much larger share of the total temperature change. Yet the absolute temperature contribution from the carbon majors remains roughly the same across scenarios. Dargan Frierson, a University of Washington associate professor of atmospheric and climate science and the study’s lead author, summarized the implication: the amount of warming attributable to the top emitters is calculable and relatively independent of future emissions, meaning their responsibility persists no matter which path the world takes.

The persistence of that warming has profound physical consequences. Even if humanity were to stop emitting greenhouse gases tomorrow, the environment would not revert to its preindustrial state. According to the study’s findings, Earth would remain approximately 1.5 degrees Celsius above preindustrial temperatures, the threshold that international climate policy has identified as a critical guardrail. Frierson put the conclusion bluntly: we expect continued warming of the climate until fossil fuel emissions stop, and the only stable future is one with no fossil fuels burned at all. In other words, there is no gentle landing. Every additional year of production by the world’s largest emitters extends and deepens the warming that future generations will inherit.

Why does past emissions translate into future disasters? The answer lies in the mechanics of attribution science, the field that connects individual extreme weather events to climate change. Over the past decade, attribution researchers have developed increasingly rigorous statistical methods to determine how much more likely, or how much more intense, a given heat wave, drought or downpour has become because of human-caused warming. These findings now form the backbone of a growing list of lawsuits attempting to hold major emitters responsible for deaths and damages incurred during climate disasters. The new study extends that logic forward in time: if persistent warming raises the baseline probability of extreme events, then gases released decades ago by leading producers may also be responsible for disasters that have not yet occurred.

This forward-looking dimension is what makes the research legally and ethically explosive. Efforts to hold emitters accountable have traditionally hinged on allegations that companies knew about climate risks many decades ago and concealed that information from the public, sometimes employing deceptive tactics to spread disinformation, as documented in archives such as the climate deception dossiers compiled by the Union of Concerned Scientists. The new analysis adds a second, quantifiable strand to that case: the gases released by extracting and burning fossil fuels are not merely a historical wrong but an ongoing mechanism of harm, one that will keep elevating the odds of future catastrophes long after the emissions themselves took place. Responsibility, as Frierson noted, is not just now; it will continue for many, many years into the future.

The timing of the study could hardly be more consequential. Courts around the world are weighing claims brought by cities, states and indigenous communities against fossil fuel producers, and the scientific credibility of attribution evidence has become a decisive factor in several of those proceedings. By showing that the warming contribution of the carbon majors is stable across emissions pathways, the research gives plaintiffs a robust number that does not depend on contested assumptions about future policy. It also gives regulators and policymakers a clear warning: future fossil fuel production will exacerbate climate disasters for many decades to come, which means new legal battles over accountability should be expected for years. Frierson emphasized that this is important for current decisions about fossil fuels, since every new extraction project adds to a warming burden that cannot be easily undone.

Underlying the entire analysis is a sober piece of climate physics. Carbon dioxide’s atmospheric lifetime is not measured in years but in centuries to millennia, and the ocean’s enormous heat capacity means that even after concentrations stabilize, the climate system continues to adjust. Reduced-complexity models like FaIR capture these dynamics by linking emissions pulses to temperature responses with well-constrained parameters drawn from the broader body of climate science. When the model runs with and without carbon major emissions diverge by a consistent margin across 500 simulated years, that margin represents real, physical, irreducible warming, heat that has already been committed to the system by past production decisions. No plausible emissions pathway can claw it back.

The study, co-authored by Lauren Henrie, a former student of Environmental Science and Resource Management at the University of Washington, ultimately reframes the climate crisis as a problem of accumulated, durable responsibility. The faucet is still running, in effect, and the water already in the house will keep spreading through the floors for generations. For the top 178 producers of oil, gas, coal and cement, the message is that their past is the planet’s future: the trillion tons of carbon dioxide already released will continue trapping heat, intensifying storms, and raising the odds of disaster long after today’s headlines fade. And for everyone else, the message is equally clear: the only stable future, the only one in which the warming finally stops climbing, is one in which fossil fuels are no longer burned at all.

Subject of Research: Attribution of long-term global warming and future extreme weather risk to historical emissions from the largest fossil fuel and cement producers

Article Title: Past emissions from top polluters will continue warming the planet for decades to come

Article References: Past emissions from top polluters will continue warming the planet for decades to come. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: carbon majors, climate attribution, fossil fuel emissions, PLOS Climate, University of Washington, FaIR model, extreme weather, climate litigation, carbon dioxide lifetime, global warming, emissions scenarios, climate accountability