Imagine if ocean currents shifted, which keep Northern California up into BC warmer, and the UK and other parts of Europe warmer.

That's a lot of farmland changed.

The inverse could happen too. Instead of no longer bringing warm water to those coasts, cold water currents could arrive. You could have snow in Norhern California for most of the year, even while the rest of the planet warms.

So many variables.

Canada has immense amounts of bog thawing, and bog/swamp is very fertile land. But it's still further North, which means short growing seasons, and too much sun for some plants per day.

We should be creating crops which can handle those conditions, even if just through normal breeding.

Ah well.