In the 1950s, U.S. nuclear tests were conducted at Bikini and Enewetak; decades later, Guam corals preserved carbon-14 spikes linked to tests in 1954, 1956, and 1958

Guam’s coral reefs act as natural historians, chronicling chemical footprints of Cold War-era nuclear tests. Distinct radiocarbon spikes from the years 1954, 1956, and 1958 reveal the pathways of nuclear fallout as it spread through the tropical Pacific. This invaluable information extracted from coral cores charts a sixty-year timeline of the ocean’s chemical changes, enabling scientists to accurately date marine species currently inhabiting these waters.