1) I redid the calculations using the numbers shown in the table. With more decimal places, it's 1.054 for outdoor and 1.036 for indoor. The actual penalty for outdoor growing, using their own input numbers, is more like 1.7% than 10%. Presenting the results rounded to 1 decimal place is misleading.
2) The only reason indoor comes out ahead at all is that they gave indoor lettuce a 0.18 kg credit for sequestered CO2 and gave the outdoor lettuce no credit. Plants absorb CO2 while growing regardless of whether they are indoor or outdoor. In the case of lettuce, there is no long term sequestration anyway; the plant matter is soon converted back to CO2 when it's metabolized by humans or microbes. Setting both indoor and outdoor sequestration credits to 0, indoor has a CO2 footprint of 1.253, significantly larger than outdoor's 1.054.
The original source for the table is cited as a blog article from the Breakthrough Institute titled "Don't Count Out Vertical Farms." I tried going back to the original source to see if the numbers were misrepresented here, or if they had more justification in the original, but the Breakthrough Institute appears to have removed the article from their site. Existing links to it 404 now.
https://thebreakthrough.org/issues/food/vertical-farms-raise...
It gets worse when you look at the footnotes. They assume that the electricity going to the vertical farm is produced at the Swedish average carbon intensity per kWh. Sweden is far below the OECD average for electrical energy carbon intensity:
http://www.compareyourcountry.org/climate-policies?cr=oecd&l...
Only Switzerland, Sweden, Iceland, and Norway have low enough electrical carbon intensities for vertical farming to have a smaller carbon footprint, even conceding the re-forestation assumption.
Growing under artificial lighting can produce crops that don't need to endure prolonged storage and shipment. Some people will pay a flavor-and-quality premium for things like fresh tomatoes, salad greens, and herbs that can be grown this way near the point of consumption. But the bombast about remaking the "global food system" this way is ridiculous. The vast majority of crops, measured either by dollar value or by calories eaten by humans, are not going to be grown this way. For most crops it would greatly increase the cost and the fossil fuel consumption if they were grown under artificial lighting, and there wouldn't even be a corresponding quality improvement to motivate buyers.
The article even says as much:
In fact, all things considered, says Mark Bomford, director of the Yale Sustainable Food Project, “it’s generally a lower-impact proposition to move food around the planet than to move the climate.”
If I wanted to get potatoes right now from the back yard dirt I'd have to remove about two feet of hard-packed ice and snow, then chisel into dirt that may as well be concrete. At least solid ice and concrete respect a pick. Wet, frozen dirt just shrugs it off.
Let me remind you that this year in places like Minnesota it was -60°F outside. Good luck getting anything out of the ground in those conditions. Even a backhoe is going to have trouble. I'd suggest using dynamite, but at those temperatures even dynamite won't work without being heated up first.
And the study that suggests indoor grown can be less carbon intense is super interesting.
A big dirty secret is that organic crops fail at both. Farmers buy special organic pesticides, for example toxic plant juice. The fertilizer is often poo.
These indoor farms are kept bug-free. They should also be free of rats and birds. If a bird craps on your lettuce, there is no way to really fully sanitize that without destroying the lettuce. You can wash it so that it looks nice and people will eat it, but you will never make it safe.
The farmers themselves are also a problem of course, particularly the lowest-paid workers who often don't get proper treatment for diseases and often don't really understand or care about sanitation. Indoor farms allow an easier transition to automation, which would greatly reduce this disease risk.
Or even do it inside.
I mostly work in climate inhospitable to farming, so I can't have a garden in my yard. But I still grow radishes, wheatgrass, and other small edible things in mason jars between the monitors and gadgets on my desk at work.
That's how the office found out one of my coworkers is terrified of crickets.
https://www.theatlantic.com/technology/archive/2011/09/weeke...
My mother is an amazing gardener because she pays careful attention to her crops and applies reasoning and careful experimentation to grow her knowledge.
Have patience, read up, and dig in. You can grow things yourself too.
Perhaps I’m becoming a Luddite...