1. Nations that drop their tariffs and quotas on agricultural imports will more easily adapt. Yes, these pro-competition actions will hurt domestic farmers but they will help urban consumers. Why? High domestic heat will lead local farmers to grow less output but supermarket prices won't rise as the local supermarket will stock the shelves with foreign imports that were not exposed to the same heat (the heat's impact at any point in time differs greatly around the world).
2. We need futures markets for agricultural output that go out more than 2 years into the future. Such scarcity signals would help both the demand side and supply side to respond. For example, if the price of oranges in the year 2022 is expected to triple from today's price (and this would be revealed by forward markets), this is very useful information. You don't have to be Hayek to see how this information would help us to adapt.
3. Declines in transportation costs (due to larger container ships and freezing technology and computerization) all help us to adapt. Why? The world is a big place. At any point in time agriculture in a given place like Kansas is not hurt by an agricultural shock while in some part of Siberia , agriculture could be having a great year. Such spatial variation creates a type of diversification. As transportation costs decline, the booming places can ship agricultural output to urban consumers. No starvation in this case, and little international volatility in prices -- just trade taking place.
4. Nations can insure against agricultural risk by spatial diversification in the cross-section (see point #3) above or they store produce. Fruit can be dried and stored for two years. Basic ideas from inventory theory and risk smoothing matter here.
5. Agriculture will move north into Canada. There is a lot of room up in Canada. Kansas and Iowa may redeploy their land for other purposes. For example, in a world of Elon Musk hyperloops they can become suburbs of Chicago. Kansas is 750 miles to Chicago. If the hyperloop can move at 750 mph , then this is just 1 hour away (I'm half kidding).
UPDATE: Professor Jeff Reimer of Oregon State University sent me the following note.
Agriculture will move north into Canada."
I wouldn't count on that. In general the soils of Canada are much worse than those of the United States. The reason is glaciers. Over tens of thousands of years they pushed all the good soil down into the Corn Belt. The soils of the Corn Belt are incredible, but they get worse the farther north you go. Back in Canada on the high plains, there's a lot of thin soils, bogs, and bare rock. So, there is no "new Illinois" or "new Iowa" to be found up in Canada.
6. Even if agricultural activity continues to concentrate in its current locations, will output of wheat collapse in the future heat? I am aware of this high quality empirical research but these are not structural time invariant estimates. At a cost, new ways will be figured out for increasing yields in areas exposed to high heat.
7. I haven't even mentioned GMO here but you can read UC Berkeley's David Zilberman's optimistic writing on this topic.
8. If the price of food increases in the developing world, then we need to help these nations unleash economic growth. It is well known that the share of income spent on food declines as nations grow richer. If the price of food is rising but food represents a smaller budget share, then this does not drag down even a poor family's overall disposable income.
So, my friendly doom and gloomers, which of the points listed above is false? Which is "2nd order"? What is the weak point in the logic here?
A richer, urbanized world has the $ to demand high quality food. I have argued that the world's population growth will slow and decline in an urbanized world (see Becker's work on fertility and the quantity-quality tradeoff).