Iron deposits dropped into the ocean won't be a viable climate change solution without further study of their potential side effects, a team of researchers says.
Sixteen scientists from seven countries released a report in the journal Science on Thursday expressing concern about the process, which is touted as a way to isolate carbon dioxide from the atmosphere.
"We do not understand the intended and unintended biogeochemical and ecological impacts" of ocean iron fertilization, said the group, which is headed by Ken Buesseler and Scott Doney from the Woods Hole Oceanographic Institution in Woods Hole, Mass.
Ocean iron fertilization (OIF) involves adding deposits of iron to the ocean in order to increase the rate of phytoplankton growth.
Phytoplankton, which thrives on iron, absorbs carbon dioxide from the atmosphere.
Since 1993, oceanographers have released small amounts of iron into the ocean 12 times in order to test whether the practice could help reduce atmospheric carbon dioxide levels.
But those tests weren't encompassing enough to determine what the long-term effects on the ocean's eco-system would be, the researchers warn.
The group recommended further tests examining the potential effects on other organisms such as fish, seabirds and bacteria.
While some private organizations are already planning to sell carbon offsets based on fertilization deposits, the researchers say it's too early to make any promises.
"It is premature to sell carbon offsets from the first generation of commercial-scale OIF experiments unless there is better demonstration that OIF effectively removes (carbon dioxide)," the report said.
Scientists from the U.S, Japan, New Zealand, the Netherlands, India, Germany and the U.K authored the report.