[jessaustin]

what happens when the area between the Mississippi and the Rockies returns to being an unusable semidesert? (That's not an if. It is all irrigated.)

Here in Missouri, there is actually fairly little irrigation. There's a 1.5 hour drive through rural farmland I take regularly, and I see one irrigation setup on the whole trip. The other irrigation I can think of off the top of my head is just north of Jefferson City, 100 yards from the Missouri River, and that's for a sod factory that turns its fields over every couple of months.

This year the rain has been fantastic. We put up more hay than we ever have. July was hot, as July often is, but the first week of August will be our coolest in memory. If this is climate change, I vote for more of it. b^)

[mcguire]

I was being hyperbolic. :)

But a large part of that region was known as the Great American Desert before the invention of suitable irrigation. And water is being removed from the aquifer much faster than it is being replaced.

[jessaustin]

Yes, things that can't continue forever, won't. Eventually much of the Great Plains will be native grassland again. That is its natural condition. The parts of Arizona and California that currently host alfalfa fields will be actual desert again, and the dairy industry will return to the Midwest where it belongs.

Even when being hyperbolic, however, you could move your border west a whole state. I doubt Minnesota, Iowa, Arkansas, or Louisiana are any more worried about the next Dust Bowl than we are. My impression is that Missouri is the driest of the states on our longitude.

[pm90]

Climate change would affect rainfall patterns as well (I assume).

[mcguire]

The last projection I saw had the Midwest becoming drier once things stabilize.