The junior traders at TotalEnergies SE were essentially winging it last September by orchestrating the French energy giant’s first shipment of "carbon neutral” natural gas. It’s the greenest-possible designation for fossil fuel and an important step in making the company’s core product more palatable in a warming world. Nailing down the deal involved Googling and guesswork.

Total had proposed the trade after learning a client had already purchased two carbon neutral cargos from rivals at Royal Dutch Shell PLC, according to people with knowledge of the deal who asked not to be named discussing a private transaction. One of these insiders said that only after getting the go-ahead did the inexperienced team attempt to figure out how to neutralize the emissions contained in a hulking tanker full of liquified natural gas. Their first step was to search the internet for worthy environmental projects that might offset the pollution.

Thousands of miles away, a Zimbabwean volunteer named Kembo Magonyo would spend the spring months clearing stubborn jumbles of branches near the thickly forested border with Mozambique. Wildfires tend to leap between the two countries, laying waste to trees before anyone can respond. "This whole bush can be razed to the ground if we don’t do what we’re doing,” Magonyo says, hacking away with his machete. His work is organized by a group partly funded by Total’s carbon-neutral deal.