WAL-MART STORES HAS BEEN TRUMPETING ITS SUSTAINABLE business practices since June 2004, when Rob Walton, an avid scuba diver and chairman of the company his father founded, organized a meeting between then-CEO H. Lee Scott and two environmentalists. Wal-Mart was facing a deluge of negative press and litigation over everything from alleged violations of the Clean Water Act and immigration law to sex discrimination, with the latter having produced the largest class-action suit in U.S. history.

Scott came to the meeting simply wanting to get the critics off his back, as author Edward Humes recounted in his 2011 book, Force of Nature. But the meeting with Jib Ellison, a white-water river expert and founder of San Francisco–based consulting firm Blu Skye, and Peter Seligmann, founder, chairman and CEO of Arlington, Virginia–based nonprofit organization Conservation International, changed Scott’s thinking about the future course of one of the biggest companies in the world in terms of revenue.

Within the walls of Wal-Mart’s one-story, starkly furnished headquarters in Bentonville, Arkansas, Ellison convinced the Joplin, Missouri–born chief executive that going green would buttress his company’s profits — and image. “Lee, the thing you have to remember is that all this stuff that people don’t want you to put into the environment is waste. And you’re paying for it,” said Ellison, as recounted in Humes’s book. “If you really want to know something cool about this whole environmental and social side of the equation, here it is: It’s a massive business opportunity.”