For Americans, the third Thursday in November can mean lots of things, usually some combination of food, family, and football. But before all that, there's the Macy's Thanksgiving Day Parade. The three-hour, 80-plus-year tradition starts at 9 a.m. and boasts 16 gigantic balloons. If you are ambitious and want to brave the cold on the night before, you can watch those balloons get inflated. In addition to seeing Kermit the Frog or Spider-Man, you'll also witness the squandering of the global supply of helium.
At projected rates of consumption, all the currently available helium on Earth will be depleted in about 40 years. While its best-known use may be filling balloons and making people who inhale it squeak like Mickey Mouse, the element's scientific uses are arguably more valuable. No other gas is as light without being combustible. Those properties, as well as its very low boiling point and high thermal conductivity, make it indispensable for aerospace engineering, deep-sea diving, and cryogenics. So, while a world with no more balloons is a sad specter, without liquefied helium we wouldn't be able to make superconducting magnets like those in MRIs.
The sorry state of our helium reserves can be traced to three key factors. Thanks to a 1996 act of Congress, the price of helium is artificially low, so there's little deterrence for overuse. There's also the fact that we have no idea how to artificially produce helium in any real, sustainable way. Finally, helium's unique properties make finding a viable substitute almost impossible.
The helium we use today is found in underground gas pockets, often associated with natural gas. Helium is abundant in the universe, but here on Earth it is more elusive; while there's a lot of helium in the atmosphere, it is very difficult to purify. It's really only when it is trapped underground that we can isolate it. This helium is largely formed as a by-product of decaying radioactive elements. The rate at which it is produced accounts for less than one-half of global demand, and most of it cannot be recovered efficiently.