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