ExxonMobil has more to lose than any other big oil and gas company as the world transitions to an economy with dramatically lower carbon dioxide emissions, a new ranking by the Carbon Tracker Initiative has found.

Up to half of the company’s projected capital expenditures through the year 2025 would go to projects that wouldn’t pay off if emissions are held low enough to keep global warming below 2 degrees Celsius, the goal of the Paris Agreement on climate change, the report says.

Carbon Tracker’s work on stranded assets—investments that would be abandoned if the world reduces emissions of carbon dioxide from the use of fossil fuels—has been increasingly influential among shareholders who are demanding that energy companies fully disclose these risks. This is the first time the organization has ranked oil and gas companies by their potentially stranded assets.

Exxon is hardly alone, but it stands out in the crowd.

Among the international oil and gas giants, Exxon has the highest percentage of its capital expenditures going to high-cost projects, which would be the first to be abandoned if carbon emissions are tightly controlled. And because it is so big, it has the most emissions exceeding the “carbon budget” that the world must balance in order to keep warming within safe bounds. About a dozen companies have a higher percentage of their assets potentially stranded, but they are much smaller.

Among all the companies examined, about a third of projected spending on new projects would be wasted—$2.3 trillion in oil and gas investments down the drain, according to the report, which was published Tuesday by Carbon Tracker along with several European pension funds and a group backed by the United Nations.

Carbon Tracker’s analysis assumed the highest-cost projects, which also tend to generate greater emissions, would be the first stranded. At the top of the list are some projects in Canada’s tar sands—where Exxon is the largest international producer—along with deep water drilling and liquefied natural gas. The report also says 60 percent of U.S. domestic gas projects ought to go undeveloped.

The report was based on a snapshot of the industry and its costs, but those costs can change dramatically over a short time. In the past four years, for example, oil companies have slashed costs in the U.S. shale oil boom by more than half.

Last month, Exxon’s shareholders approved a resolution requiring the company to report on its climate risk.

James Leaton, Carbon Tracker’s research director, said the group wants to help identify specifically where the trouble may lie before it’s too late. The group looked at projected spending through 2025, and in many cases companies haven’t yet decided whether to invest in particular projects.  

“That’s better for investors,” he said, “because it’s much harder to say, well you’ve already spent X billion on this, now we want you to give that back.”