May 4, 2021 Two geologists walk into a bar. The first one says to the bartender, “You know, soon there’s going to be a shortage of sand.” The bartender looks up, waiting for the punchline. The second geologist says, “He’s not kidding and that’s not a joke.” Conjure up images of the Sahara, Gobi deserts or the dunes of Tottori — there are plenty that work; roughly one-third of the Earth’s surface is officially classified as desert, much of it sandy — and it’s hard to believe that worries about a sand shortage aren’t an inside joke among environment researchers.