Where does this need for an insurance policy stops? If Europe's trade and defense agreements are insuficient, then perhaps each country should aim for a 3x overproduction, to cover those bad agricultural years? Maybe each city should too? Or perhaps each citizen, we should all retreat to rural homesteads and live on pasture-fed cow meat - a demonstrably unsustainable dystopia that will turn the entire planet into a giant ball of dung and guarantee eventual starvation for every sentient creature inhabiting it? But at least the rural voters would be among the last to die, so there's that.