Interesting point about the corn belt moving. Having a rough look at temperature isotherms and the location of the corn belt, it looks like it will take > 10F of warming to move it to the Canadian border. So it will likely only become an issue if we fail to address climate change this century.
Of course that is an average, North America could see a below or above average change in temperatures in that time. And with Crops, there is more than just temperature, there is also sunlight levels and rainfall and soil fertility etc.
I am not saying "corn will move x miles per year every year exactly until it crosses the border". More that places that can grow crops will change. So farmers will have to change their crops (or move) and people will have to change what they eat and places that are used to having an abundance may find they cannot grow anything. All of that is expensive and difficult and disruptive. This is the problem with any change, even a net good change.
With this also being a net negative AND an international change, it will be hard to manage even if we do suddenly find a huge amount of wealth and political will to help us...
