Hyderabad: A new analysis has attempted to put a human cost on the greenhouse gas emissions associated with fossil fuels sold by Norway-based energy company Equinor, using a developing area of climate science known as attribution science.

What was the study methodology?

A briefing by Norwegian nonprofit KlimaKultur estimates that fossil fuels sold by Equinor since 2018 could ultimately be associated with 260,000 to 450,000 additional deaths.

The estimate is based on about 2,000 million tonnes of CO₂-equivalent emissions from the use of products sold by the company during that period and published estimates of mortality associated with additional carbon emissions.

Comparing ‘estimated health consequences’

The analysis does not identify individual deaths caused by Equinor.

Instead, it compares the estimated health consequences of a world in which those emissions occurred with a counterfactual world in which the emissions did not occur.

That distinction is central to understanding what the numbers mean.

From emissions to heatwaves

Climate attribution has traditionally been used to determine whether human-caused warming made a particular extreme weather event more likely or more severe.

A 2025 study published in Nature expanded this approach by examining 213 major heatwaves between 2000 and 2023.

The researchers found that human-caused climate change had made every heatwave in their dataset more likely and more intense. They then assessed the contribution of 180 major fossil-fuel and cement producers, known as carbon majors, to the warming associated with those events.

Climate-model simulations

The researchers used climate-model simulations to compare the actual climate with a hypothetical climate in which emissions from individual carbon majors were removed.

This allowed them to estimate how much each producer contributed to the warming that increased the probability or intensity of individual heatwaves.

The study found that the emissions of the 180 carbon majors collectively accounted for about half of the increase in heatwave intensity across the events examined. It also found that the role of human-caused warming in heatwaves has increased over time.

The research included heatwaves from across the world. Eight events in India were among those analysed. Reporting on the study noted that the May 2006 heatwave in India was made substantially more likely by human-caused climate change.

Adding mortality to the calculation

The Equinor analysis takes this attribution framework another step by applying estimates of mortality associated with carbon emissions.

According to KlimaKultur, previous research has estimated the mortality cost of carbon at between 138 and 225 additional deaths per million tonnes of CO₂-equivalent emissions.

What do the estimates predict?

Applying those estimates to Equinor’s reported emissions from the use of products sold since 2018 produces the estimate of 260,000 to 450,000 additional deaths over time.

For 2025 alone, the analysis estimates that Equinor’s fossil-fuel products accounted for about 257.8 million tonnes of CO₂-equivalent emissions. Using the same mortality estimates gives a projected 34,000 to 58,000 additional deaths.

These figures should therefore not be interpreted as a current death toll. They are projections derived from emissions and statistical estimates of the relationship between warming and mortality.

Why the distinction matters

Attribution science cannot establish that one company’s emissions caused a particular person’s death in the way a medical examination can establish an immediate cause of death.

Climate-related mortality is influenced by many factors, including temperature exposure, age, existing health conditions, access to healthcare and the ability of communities to adapt to extreme heat.

How emissions combine to contribute to warming

Greenhouse gases from different sources also mix in the atmosphere.

What attribution studies can increasingly establish is a chain of contribution: emissions from a particular source add to atmospheric greenhouse-gas concentrations; those emissions contribute to warming; warming changes the likelihood and intensity of extreme heat; and extreme heat increases health risks.

That chain is particularly relevant in countries such as India, where extreme heat already poses a substantial public-health challenge.