> Every ecosystem has a carrying capacity. We're coming closer and closer to that for the Southwestern US.
The limit of carrying capacity is the limit of sustainability. If the system is coming closer to the carrying capacity, the current state, having 40 million people with lawns, is sustainable!
If your argument is that having 200 million people with lawns is unsustainable, say that! But that's not what you said.
It's not just lawns; you're being purposefully obtuse.
There are already towns in California experiencing spells of not having any potable water [0]. We've pumped so much water out of parts of California that some land has dropped almost 30 feet [1]. Wildfire season in the southwest, including California, is now longer and more severe than it once was [2]. Arizona has passed resolutions imploring Congress to investigate diverting water from the Mississippi River out west [3] which is almost guaranteed to cause serious political confrontations.
So, no, the current state of things and the projected growth isn't sustainable. When you're honestly considering the idea of building a continent-wide aqueduct system to keep golf courses in Phoenix playable, you're better off packing up and heading back to the Midwest and Northeast to repopulate towns that have infrastructure we already bought and paid for decades ago.
The limit of carrying capacity is the limit of sustainability. If the system is coming closer to the carrying capacity, the current state, having 40 million people with lawns, is sustainable!
If your argument is that having 200 million people with lawns is unsustainable, say that! But that's not what you said.