[portofcall]

At 3000 feet it’s about .9 atmospheres of pressure, but honestly humidity is incredibly variable. The lower pressure at 3k feet just places an upper bound on possible humidity, it doesn’t tell you what it is. My instinct is that you’re right, and we’re still talking about vast volumes of moist air. We could also “enrich” the air with solar powered evaporation of seawater and wastewater.

[jerf]

For the purposes of this discussion I'd say order-of-magnitude is close enough, and I doubt the number for Death Valley is off by more than two orders at most (taking into account the possibility that Death Valley is just too special to use the normal numbers on). It will take a lot of work to disrupt even a desert ecosystem by extracting water from the air, and we are precluded from even wanting to do that work by the immense energy expense it will involve.

[portofcall]

I agree, if we had the viable and affordable tech to do this, it would be low environmental impact. When you consider the impact of large scale ocean desalination, it would be a clear green choice.