“If you go to a warehouse, it’s much more efficient because there’s no customers to make comfortable,” Webber said. “Your workers can wear insulated overalls. So you refrigerate the whole thing and it’s more efficient.” Grocery stores also add another step in the supply chain from farm to consumer that results in additional food waste, another huge climate problem.

It’s for all of these reasons that, while Miller hasn’t seen the study Bezos references in his shareholder letter, she thinks that its conclusion that online grocery shopping delivers carbon savings over driving to the store “make sense.” So does Anne Goodchild, a supply chain and transportation logistics researcher at the University of Washington. The 43 percent emissions reductions figure quoted in the shareholder letter, she said, is “certainly not outside the range of outcomes we’ve seen in our studies” that looked at the transportation and logistics of grocery delivery.

Webber had a slightly more cautious take. “It depends,” he said.

Indeed, while Amazon can tout the benefits of online grocery shopping all it wants, that doesn’t mean getting an Amazon Fresh box delivered to your doorstep is the most eco-friendly choice you can make. If you’re already walking, biking, or driving a Tesla to the grocery store, getting your eggs and milk dropped off via a truck will likely cause their last-mile emissions to rise. Switching to online shopping might also change your shopping behavior in ways that make it worse for the environment. Perhaps, instead of getting all of your groceries in one carefully planned shopping outing, you start placing lots of smaller orders online, resulting in more truck trips.

Or perhaps your online ordering isn’t replacing your personal grocery store trips at all, but merely supplementing them. “This is a huge one,” Webber said. “Is this a replacement or an alternative? While we’re quarantined it looks like a replacement,” but that might not continue to be the case as lockdown restrictions start to ease.

“Amazon has all kinds of data about their own operations,” Goodchild said. “What they don’t know is how people behave. So it’s all based on assumptions.”

It’s also important to bear in mind that how our food makes that last-mile journey to our doorstep has a much smaller climate impact than the types of food we’re eating. In a recent study comparing the environmental impact of meals prepared from Blue Apron meal kits with those same meals made from grocery store ingredients, Miller and her colleagues found that food production was responsible for more than 65 percent of a meal’s total carbon footprint. Raising cattle, for instance, requires significant land and resources, which, along with the animals’ methane burps, contribute to beef’s outsized climate impact. Other types of meat and dairy products also tend to have a high carbon footprint, because they take more energy and resources to produce compared with fruits and vegetables.

Compared with food production, Miller’s study found that last-mile emissions, meanwhile, averaged just 4 percent of the carbon footprint for meal kit meals, and 11 percent for grocery store meals.

“Transportation and logistics associated with the last mile are a pretty small overall contribution to the total environmental impact of food,” Miller said. The “only possible way” Amazon could have arrived at a 43 percent carbon savings for online delivery, she said, is if the company was only looking at transportation and logistics and not at food production (as was the case in the other studies Goodchild cites).

There are also bigger picture considerations about how the rise in online shopping we’re witnessing due to coronavirus will impact our food system in the long term. Emily Broad Leib, director of the Harvard Law School Food Law and Policy Clinic, says that while getting groceries delivered seems like the “right direction to go” from a public health standpoint right now, she worries this trend will make it even harder for smaller retailers and family farms to compete. Broad Leib notes that in nearly every state where low-income families can purchase groceries online with food stamps through the Supplemental Nutrition Assistance Program (SNAP), Amazon and Walmart are the only approved retailers.

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