Walmart is partnering with the Environmental Defense Fund on a green initiative called Project Gigaton, which will reduce a gigaton of greenhouse gas emissions from Walmart’s supply chain by 2030. While the program was announced in April, a joint commentary was published on CNBC this week (presumably in response to the U.S. government starting withdrawal from the Paris climate agreement), and explained the thinking behind this initiative and other environmental efforts.

Walmart believes it needs to be nimble, but also needs to stay the course on some long-term commitments, in spite of “shifting winds.” The program will result in an emissions reduction equivalent to taking 211 million cars off the road for a year.

Walmart began to embrace environmental issues more fully in 2005, when it found itself an early responder,…