A new study challenges the longstanding theory that glacial meltwater can mitigate climate change by feeding algal blooms. Findings published in Nature Communications Earth & Environment indicate that meltwater from an Antarctic ice shelf releases significantly less iron into the ocean than previously believed. This research was led by principal investigator Rob Sherrell, a biogeochemistry professor at Rutgers University.
The study focused on the Amundsen Sea, which experiences the fastest ice shelf thinning in Antarctica and is a major contributor to rising sea levels. Researchers collected water samples at the Dotson Ice Shelf where seawater enters and exits cavities beneath the ice. Analysis revealed that only about 10% of the dissolved iron in the outflow originated from meltwater, while 62% came from deep ocean inflow and 28% from shelf sediments.
This real-world data contradicts earlier simulations that supported the iron fertilization hypothesis. Sherrell emphasized that the majority of iron in meltwater results from the erosion of bedrock beneath the ice, rather than from the ice itself, casting doubt on the potential of glacial melt to slow global warming.