Researchers from the University of Sheffield have discovered that melted water stemming from giant icebergs, which contain iron and other beneficial nutrients, stimulates high levels of phytoplankton growth. This process, also known as carbon sequestration, may benefit global warming by contributing to the long-term storage of atmospheric carbon dioxide, which is one of the greenhouse gases stimulating the problem.
The scientists analyzed 175 satellite images of ocean color - known to be an indicator of phytoplankton productivity - from various icebergs in the Southern Ocean, all of which were at least 18 kilometers in length. The team found that increased phytoplankton productivity, which directly impacts carbon storage in the ocean, extends from icebergs for hundreds of kilometers and this effect lasts for at least one month after the iceberg is gone.
"We detected substantially enhanced chlorophyll levels, typically over a radius of at least four - 10 times the iceberg's length," said Grant Bigg, who headed the research, in a press release. "The evidence suggests that assuming carbon export increases by a factor of five-10 over the area of influence and up to a fifth of the Southern Ocean's downward carbon flux originates with giant iceberg fertilization."
"If giant iceberg calving increases this century as expected, this negative feedback on the carbon cycle may become more important than we previously thought," he added.
The findings conflict with previous studies that found that ocean fertilization from icebergs is just a minor contributor to the amount of carbon dioxide taken in by phytoplankton and could help researchers better understand how the Southern Ocean contributes to the carbon cycle and, in turn, global warming.
The findings were published in the Jan. 11 issue of Nature Geoscience.
