1. The UN (did you hear that, lefties? The U-freakin'-N!) says that cow farts are the world's greatest threat to climate, forests, and wildlife. Didn't we hear this story in the 80s, and wasn't it poo-poo'd (pardon the pun) then?
2. Local pollution will destroy some pre-Aztec stone murals in "10, 20 or 100 years". Unless Mexico implements stricter pollution controls, this will continue. Acid rain was a topic of discussion in the US Northeast back in the early 80s, a topic that was sometimes discussed at West Point (with it's granite-like buildings).