Just approach it from a planetary scale. Total planetary demand is local + overseas demand. Suppose it was 5 + 5 units = 10.
If you reduce local demand by 2 and overseas demand remains at 5, then total demand will go down to 8.
Any economics 101 course will teach you that reducing demand will the equilibrium price, at which price point fewer suppliers are willing to supply. The end result is less production, less consumption on the planet.
As a thought experiment, imagine 90% of the world population disappears tomorrow (demand disappears). Will we produce just as much, simply because the remaining 10% will consume more? The answer is obviously no.
Demand/supply curves aren't flat, so indeed the change will not be 1:1. It's not the case that if 10% stop eating meat, that total consumption will drop by 10%. But demand reduction from one group does lead to a total production reduction and a total reduction in consumption.
If you reduce local demand by 2 and overseas demand remains at 5, then total demand will go down to 8.
Any economics 101 course will teach you that reducing demand will the equilibrium price, at which price point fewer suppliers are willing to supply. The end result is less production, less consumption on the planet.
As a thought experiment, imagine 90% of the world population disappears tomorrow (demand disappears). Will we produce just as much, simply because the remaining 10% will consume more? The answer is obviously no.
Demand/supply curves aren't flat, so indeed the change will not be 1:1. It's not the case that if 10% stop eating meat, that total consumption will drop by 10%. But demand reduction from one group does lead to a total production reduction and a total reduction in consumption.