However, if some tales of survivalist stockpiling are to be believed, our nutty neighbors have enough of the social lubricant squirreled away to hold the most epic end-of-the-world-party of all time outside of Edgar Wright's social circle. It might not be practical, but who needs practical when you and everyone you know is doomed to die from radiation poisoning or cancer?
For global catastrophic risks the costs of food storage become impractical for most of the population  and for some such catastrophes conventional agriculture would not function due to the loss of a large fraction of sunlight (e.g. during nuclear winter or a supervolcano). In such situations, alternative food is necessary, which is converting natural gas and wood fiber to human edible food.