U.S. oil majors like Exxon and Chevron are failing to grapple with the energy sector’s transition away from polluting fossil fuels and refusing to disclose potential risks to their portfolios from assets that may become “stranded,” or uneconomical to develop, in a low-carbon world, new research from the London-based think tank Carbon Tracker shows.

Exxon, for example, stands to lose at least 80 percent of its business-as-usual petroleum investments if the world takes action to limit global temperature rise to 1.6 degrees C (2.9 degrees F), a limit that is within the “well below 2 degrees C” goal prescribed in the Paris Climate Agreement.