The cotton in my clothes doesn't come from the US, and neither does that of the vast majority of world's people. Besides that, surely you're aware that the American South is going to increasingly suffer from droughts as well? It's pretty disingenuous to assume that just because historically rainwater has been sufficient, it's going to be so in the future as well.

Also, agriculture isn't necessarily sustainable just because it doesn't require artificial irrigation. As an extreme example, just look at the Amazon. The land used to grow a water-intensive species might be better used for other purposes.

The US bans most of the cotton from China, the worlds largest producer, because of slavery. The US also produces a third of global cotton and is the leading exporter. You certainly have some American cotton in your closet, a huge portion of the people around the world will have American cotton in their clothes.

And for the rest... talking to climate doomers isn't interesting or productive. You'll only believe negative things, you demonstrably here don't know what you're talking about and just make things up to fit the narrative you have in your head. You clearly knew nothing about cotton production but made up facts without bothering to look for information at all. You make up your climate facts as well, do you know anything about the climate models for what will happen in the cotton growing regions of the US? Or have you heard vague things about droughts and decided to parrot those and assume they apply here because they supported your doom thoughts?