Why does agriculture produce an excess that doesn't get sold? Because the less is produced, the more prohibitively expensive production becomes per unit due to power laws. Hence why it's far more cost effective to cultivate a large volume of livestock compared to sustenance farming.

Meat is a great example. As the demand for cheap meat is high, agricultural enterprises have optimized their production of livestock in order to attain an optimum profit margin per individual unit. For instance, the financial upkeep of infrastructure remains the same whether you have one 1 cow or 10 cows. If you raise and sell 10 cows, the production cost per individual cow goes down. Then there's market demand and supply. The cheaper the price per unit, the more an enterprise needs to produce if it wants to stay competitive. Hence why mega-farms exist.

While the financial cost or production per unit of food has dropped exponentially in the 20th century, the carbon cost for that same unit has increased tremendously.

Harking back to your original statement about plastic. It's true that wrapping food in plastic allows for longer conservation per unit. But then this effect is largely negated because:

Producers will keep on producing excess volumes in order to drive financial production costs down and meet market prices. Retail chains will keep buying large bulk quantities to drive costs down and throw the unsold excess away. What you conserve in your fridge gets wasted elsewhere along the entire chain from cradle to consumer. The carbon costs, however, pretty much remain the same.

Production and processing of disposable plastic wrapping just adds to the carbon cost of excess production.

One conclusion you could draw from all of this is that we simply shifted the cost of food consumption from a financial to an ecological cost. If we want to reduce emissions created by industrialized farming, then there are few options ahead of us.

There's the technological road in which we look for ways of capturing excess emissions, but this might prove extremely hard and raises all kinds of ethical questions re: GMO's or how we treat animals. How much wiggle room do we have to implement solutions that keep the consumer price of food as they are?

The other road is... produce less, reduce production an order of magnitueds in order to reduce carbon emissions and pay the actual cost of food as a consumer. That is, increase the price of meat and other produce so it reflects the true cost of the impact on the environment.

When you start thinking about the true cost of food, then you may look at the past and at how we approach food. Our culinary culture around the world. With the advent of globalization and mass-consumption, something else happened: the gradual replacement of local cuisine - based on local produce and associated habits - by western diets which contains ingredients with a high carbon cost.

I recommend watching Michael Pollan's Cooked series on Netflix in order to get the idea of what cooking really means across the world and the impact of this evolution on our dietary choices. (https://www.youtube.com/watch?v=epMAq5WYJk4).

Our habits and behaviour as consumers really is one of the big keys to this problem.

When you come to think of it, there's little reason why millions of people in Europe or America should be able to buy tiger prawns on a daily basis produced in the Mekong delta at discount prices worth pennies. If there is a high demand for tiger prawns, then that's likely a demand created because of their mere availability and low price in supermarket chains.