↵‡ Present address: Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA. ↵§ Present address: Department of Chemistry and Physical Sciences, Quinnipiac University, Hamden, CT 06518, USA. Breaking waves produce bubble plumes that burst at the sea surface, injecting primary marine aerosol (PMA) highly enriched with marine organic carbon (OC) into the atmosphere. It is widely assumed that this OC is modern, produced by present-day biological activity, even though nearly all marine OC is thousands of years old, produced by biological activity long ago. We used natural abundance radiocarbon (14C) measurements to show that 19 to 40% of the OC associated with freshly produced PMA was refractory dissolved OC (RDOC). Globally, this process removes 2 to 20 Tg of RDOC from the oceans annually, comparable to other RDOC losses. This process represents a major removal pathway for old OC from the sea, with important implications for oceanic and atmospheric biogeochemistry, the global carbon cycle, and climate. Most dissolved organic carbon (DOC) in the sea is remarkably old [averaging up to 6500 radiocarbon (14C) years] (1–3), persisting much longer than the time scales...