Joshua trees are "trees" (I think they're actually more like bushes that look like trees, they're a type of yucca) that are found basically only in the the US high desert area of Southeastern California and the surrounding area. They're disappearing at an alarming rate. I've been to Joshua Tree National Park a few times in my life and it's staggering how desolate it looks nowadays (I went last year). There's still lots of life, sure, but the actual joshua trees? Gone. Just gone. I don't recall all the specifics of the issue but you can go look it up for yourself, it's definitely a global warming impact though and is one of the US desert poster children for "look at what global warming is doing to the ecology." An entire national park named after the trees because they're rare and cool now basically empty of the tree the park was named after. It's sad shit.