Throughout the 1950s, the US, the Soviet Union, and others tested thermonuclear weapons in the Earth’s atmosphere. Those tests released vast quantities of radioactive material into the air and triggered fears that the nuclear reactions could ignite deuterium in the oceans, thereby destroying the planet in a catastrophic accidental fireball.
Atmospheric tests ended in 1980, when China finished its program, but the process has left a long-lasting nuclear signature on the planet. One of the most obvious signatures is cesium-137, a radioactive by-product of the fission of uranium-235.
After release into the atmosphere, cesium-137 was swept around the world and found its way into the food supply in trace quantities. Such an addition is rarely welcomed. But in 2001, the French pharmacologist Philippe Hubert discovered that he could use this signature to date wines without opening the bottles.
The technique immediately became a useful weapon in the fight against wine fraud—labeling young wines as older vintages to inflate their price. Such fraud can be spotted by various types of chemical and isotope analysis—but only after the wine has been opened, which destroys its value.
Cesium-137, on the other hand, allows noninvasive testing because it is radioactive. It produces distinctive gamma rays in proportion to the amount of isotope present. Dating the wine is a simple process of matching the amount of cesium-137 to atmospheric records from the time the wine was made. That quickly reveals any fraud. Indeed, if there is no cesium-137, the wine must date from after 1980.
There is one blip in this record, though. The Chernobyl disaster in 1986 bathed much of Europe, and other parts of the world, in a radioactive cloud that increased atmospheric levels of cesium-137 again. Hubert and colleagues can see this blip in their data from wines.
