Overview
- Researchers measured extraterrestrial helium-3 alongside thorium-230 in Arctic seafloor sediments to reconstruct a continuous sea-ice history spanning roughly 30,000 years.
- Sediment cores from three contrasting sites captured modern patterns from year-round ice to a location that shifted from permanent to seasonal cover within about four decades.
- Results indicate the central Arctic remained perennially ice-covered during the last glaciation, retreated around 15,000 years ago, and became more seasonal in the early Holocene before later increases.
- The study links lower ice coverage to higher phytoplankton-driven nutrient consumption, suggesting ecological shifts as light penetration increases with ice loss.
- Authors caution that findings are based on only three cores and call for broader sampling, as satellite data since 1979 already show a more than 42% decline in sea-ice extent with projections of summer ice-free conditions within decades.