The “10 tomato plants per person” number makes things look pretty dire, in my eyes.
World population is about 7,800,000,000. The population of Germany is about 83,000,000. That makes roughly 940 tomato plants to offset the CO2 emission of one person.
Even putting that number aside, tomato plants are not exactly small plants. A significant part of world population won’t have the leisure to keep even one, let alone ten, tomato plants (or the equivalent in other plants). Think people who live in slums, people who live in dense areas (e.g. people who subsist with minimum wage in subdivided apartments in HK).
Yes, we should definitely grow plants, but even more so, we need to consume way waaaay less.
The number that the author states is not just "10 tomato plants per person". But it is "10 tomato plants per person per year".
So that means to compensate for the stated amount of CO2, you need to plant 10 tomato plants extra each year (the second year you would have 20, the third year you would have 30, etc.).
Sure, you would grow 10 new plants every year since Tomatoes are mostly grown annually (while can be also grown perennial). I should have made that more clear in the blog post.
> Yes, we should definitely grow plants, but even more so, we need to consume way waaaay less.
Wouldn't it be the best when these two are actually the same? When growing more enables you to consume less? I didn't account for the savings you would do with consuming less in my simple calculation.
A large part of our consumption is not food. You can’t grow iPhones on a tree. You’re not going to consume less iPhones because you planted hundreds of tomato trees. You could argue that you can offset the total lifecycle energy for owning an iPhone (mining, purification, synthesis of raw materials, manufacture, packaging, transportation, recycling), by planting enough plants, but how many plants is that going to take?
I mean, I'm a software engineer by training. Back in university, we had a courses on engineering ethics, environmental responsibility, stuff like that. That's where I learned the concept of lifecycle energy assessment. I know it's a thing, but I never learned how to actually do the assessment (e.g. where to pull figures, the kind of ballpark calculations you do).
It might be interesting to make the methodology of lifecycle energy assessment more accessible to the general populace. I think everybody can benefit from a new perspective.
I think this is a large oversimplification. What the author states is not just "10 tomato plants per person". But it is "10 tomato plants per person per year". In this calculation, the plant's CO2 respiration during life is considered, but not the CO2 respiration after death.
So that means to compensate for the stated amount of CO2, you need to plant 10 tomato plants extra each year (the second year you would have 20, the third year you would have 30, etc.). That is not taken into account that it is challenging to overwinter plants outside.
According to the first referenced article[1], the tomato plant stores the largest part of the CO2 in its fruits. If you eat your freshly grown fruits, you will respirate (a large amount of) this CO2 again.
Besides that, I enjoyed the read. I had nine tomato plants on my balcony this past summer. They take a lot of room and a lot of work, but it is lovely to eat your own homegrown fruits. I can recommend it to anyone! I only think the calculation is way off.
Thanks for your comment. My calculation is simple and is there to get the discussion going. What's the reason of adding another 10 each year?
When composting the tomatoes properly (even in place) you can grow the next years 10 in the debris. Tomatoes love to be grown in composted tomatoes!
If you grow one tomato plant each year, eat the fruit and compost the rest - there’s a carbon cycle happening. Atmospheric CO2 is turned into sugars and carbohydrates via photosynthesis in the plant. Then the plant is eaten (the fruit by a human, the rest by bacteria, fungi, nematodes, etc. in your compost). The process of digestion/metabolisation is that the carbohydrates/sugars are broken down for energy and respired back into the air as carbon dioxide. Back to where we started
The net change to the amount of CO2 in the atmosphere is roughly zero per year if you start with no tomato plant and end with eaten tomatoes and compost*
If you want to sequester carbon then you have to (a) increase the biomass of plants year after year or (b) take plant matter (or animal matter) out of the carbon cycle for good. That means doing something like burying it or dropping it to the bottom of the ocean. Anywhere where there’s no oxygen (the O in CO2). That’s what happened to the gigatons of algae and plankton that turned into the oil we’ve had so much fun burning.
* I believe healthy soil does store more carbon than dead dirt so if your ongoing growing is improving the soil every year then you might be winning a bit.
Hey HN community, Thank you for the great discussion we had last time[1]! A lot of people reached out and spawned some very interesting conversions. Happy to jump right back in, reading how you tear apart my numbers :)
World population is about 7,800,000,000. The population of Germany is about 83,000,000. That makes roughly 940 tomato plants to offset the CO2 emission of one person.
Even putting that number aside, tomato plants are not exactly small plants. A significant part of world population won’t have the leisure to keep even one, let alone ten, tomato plants (or the equivalent in other plants). Think people who live in slums, people who live in dense areas (e.g. people who subsist with minimum wage in subdivided apartments in HK).
Yes, we should definitely grow plants, but even more so, we need to consume way waaaay less.