The 36 Cl Bomb‐Pulse in Ice at a High‐Accumulation Site in Antarctica

A global tracer for nuclear fallout, the radioisotope 36 Cl, has been used to deduce key atmospheric exchange times. Produced in large quantities during high-yield thermonuclear tests at Bikini and Enewetak Atolls in the 1950s, 36 Cl was dispersed worldwide via the stratosphere. Measurements from an Antarctic ice core reveal a one-way transport dominance, simplifying interpretation of its movement between the stratosphere and troposphere. The study estimates exchange times of 3.7 years for stratosphere-troposphere gaseous exchange and 4.2 years for interhemispheric stratospheric exchange, providing an independent constraint on ozone flux that aligns with other direct estimates.

Fifield, L. K., Etheridge, D. M., di Tada, M. L., Liu, K., Cresswell, R. G., & Keywood, M. D. (2025). The ³⁶ Cl Bomb‐Pulse in Ice at a High‐Accumulation Site in Antarctica. Journal of Geophysical Research: Atmospheres, 130(24). Portico. https://doi.org/10.1029/2025jd044388