Just 32 fossil fuel companies were responsible for half the global carbon dioxide emissions driving the climate crisis in 2024, down from 36 a year earlier, a report has revealed.

Saudi Aramco was the biggest state-controlled polluter and ExxonMobil was the largest investor-owned polluter. Critics accused the leading fossil fuel companies of “sabotaging climate action” and “being on the wrong side of history” but said the emissions data was increasingly being used to hold the companies accountable.

State-owned fossil fuel producers made up 17 of the top 20 emitters in the Carbon Majors report, which the authors said underscored the political barriers to tackling global heating. All 17 are controlled by countries that opposed a proposed fossil fuel phaseout at the Cop30 UN climate summit in December, including Saudi Arabia, Russia, China, Iran, the United Arab Emirates and India. More than 80 other nations had backed the phaseout plan.

Saudi Aramco was responsible for 1.7bn tonnes of CO2, much of it from exported oil. If it were a country, Aramco would be the world’s fifth biggest carbon polluter, just behind Russia. ExxonMobil’s fossil fuel production led to 610m tonnes of CO2 – it would be the ninth biggest polluter, ahead of South Korea.

Since a blip during the Covid pandemic, continued fossil fuel burning has led to carbon emissions resuming their annual rise to record levels each year. Emissions would have to fall by 45% by 2030 to meet the Paris agreement’s goal of 1.5C, a target now seen as impossible. But limiting the overshoot is vital, say experts, as every fraction of a degree of heating worsens the climate impacts on communities.

Emmett Connaire, of the thinktank InfluenceMap, who led the report, said: “Each year, global emissions become increasingly concentrated among a shrinking group of high-emitting producers, while overall production continues to grow.”

Recent oil sector mergers have included ExxonMobil acquiring Pioneer Natural Resources and Chevron acquiring Hess.

Tzeporah Berman, of the Fossil Fuel Non-Proliferation Treaty Initiative, said: “This latest analysis reinforces a stark reality: a powerful, concentrated group of fossil fuel corporations are not only dominating global emissions but are actively sabotaging climate action and weakening government ambition.”

The initiative aims to deliver international cooperation that halts fossil fuel expansion and starts a just transition away from coal, oil and gas. Berman said an April meeting in Colombia of the 80 countries backing a fossil fuel phaseout was a critical step towards securing a sustainable future.

Christiana Figueres, a former UN climate chief, said: “The latest Carbon Majors data shows once again that large emitters are on the wrong side of history. While clean energy and electrification is already receiving nearly twice the investment of fossil fuels globally, carbon majors are clinging on to outdated, polluting products. But data provides a tool for the growing majority who are coming together to champion science-backed solutions and accountability.”

The Carbon Majors database underpinned recent analysis that directly linked carbon emissions from the world’s biggest fossil fuel companies to dozens of deadly heatwaves that otherwise would have been virtually impossible. The data also enabled another study to attribute trillions of dollars in economic losses related to extreme heat to individual fossil fuel companies.

The database has also provided evidence in legal cases, such as Lliuya v RWE, a landmark German climate litigation case, and climate superfund laws in New York and Vermont that require large fossil fuel companies to pay for projects to protect citizens against climate impacts such as flooding and extreme heat.

Rebecca Brown, the head of the Center for International Environmental Law, said: “The evidence just keeps mounting. The international court of justice and courts around the world are increasingly connecting the dots between fossil fuel production and climate destruction, making clear that big polluters must phase out fossil fuels and pay up. And when the facts are plain and the law is clear, accountability must follow.”

Saudi Aramco declined to comment and ExxonMobil did not respond to a request for comment.