Gatineau Park Maple Leaves Reveal Lingering Cold War Nuclear Testing Radiocarbon
A recent study led by the André E. Lalonde National Facility for Accelerator Mass Spectrometry (AEL-AMS) at the University of Ottawa has found that the radiocarbon legacy of Cold War-era nuclear weapons testing has only recently disappeared from the local biosphere in Gatineau Park. For over six decades, scientists have collected sugar maple leaves from the park, creating the longest continuous record of its kind. This research, published in Scientific Reports, analyzed these leaves, which act as a 65-year diary of the atmosphere. Above-ground nuclear tests conducted primarily by the United States and the Soviet Union in the late 1950s and early 1960s released significant amounts of radiocarbon, roughly doubling global levels in what scientists call the “bomb pulse.” The study indicates that while direct air measurements showed atmospheric radiocarbon dropping below pre-bomb levels around 2021–2022, local maple leaves only crossed this threshold in 2024, demonstrating a lag in biological systems.
