“I was struck by how large an announcement this was, by just how big a transformation she was describing,” says Fortune senior editor Geoff Colvin, who has covered General Motors for “quite a while.”

GM, which sat at the top of the Fortune 500 list for many years, started sliding down the list in the early 2000s. Mary Barra stopped the slide and, now, is positioning the company to go up against electric vehicle (EV) powerhouse Tesla as well as Volkswagen, which is also, Colvin says, “investing billions and billions of dollars in EVs.”

Will General Motors’s gamble on EVs pay off? And can GM’s shift away from internal combustion engines really help fight climate change?

“Transportation is responsible for the largest … share of U.S. emissions,” says Jody Freeman, the Archibald Cox Professor of Law and director of the Environmental and Energy Law Program at Harvard Law School. By making a huge dent in cutting its vehicles’ contributions to U.S. emissions, GM and other manufacturers will make a “massive step toward the Biden pledge to reduce the country’s emissions between 50% and 52% by 2030, and to get to net zero by 2050.”

Of course, GM doesn’t exactly have a history of being pro-environment.

The change will be the “biggest transition that we’ll ever see—or almost anybody has ever seen—in the U.S. auto industry,” says John Murphy, managing director and lead U.S. auto analyst with Bank of America Securities.

But what that will mean for the day-to-day within GM’s plants may not, according to the company, be all that big of a shift.

“What’s going to be a transformation for our industry is only going to be a transition for manufacturing,” says Gerald Johnson, GM’s EVP of global manufacturing and sustainability. He adds that 80% of the work at the assembly plants will remain as-is for gas-powered vehicles, with just 20% of the process adapted to accommodate the transition to EVs.

Freeman, Murphy, and Johnson join Fortune cohosts Beth Kowitt and Geoff Colvin on Fortune‘s Reinvent, a podcast about fighting to thrive in a world turned upside-down, to talk about GM’s massive shift in focus to electric vehicles. Listen to the full episode below.

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