[richardknop]

In case of major disaster such as meteorite hitting a metropolitan area, just in time logistics systems mean most major cities such as New York or London have enough food to survive for 2-3 days. If something happens that disrupts the supply chain 10 of millions of people will be starving in couple days. Imagine if something serious happened. In a week there would be anarchy and total collapse of law and order.

[TeMPOraL]

Which is why the most important constraint in dealing with climate change is ensuring that scenario never happens.