Using ocean fertilization to fight global warming has little chance of success, an independent group of experts concludes in a report released today.
Scientists first suggested in the late 1980s that adding iron or other nutrients to nutrient-poor ocean regions might stimulate blooms of photosynthesising algae. They reasoned that the growing algae would remove substantial amounts of the greenhouse gas carbon dioxide from the atmosphere, so slowing the rate of global warming.
But the scheme is unlikely to work, according to an expert group commissioned by the Intergovernmental Oceanographic Commission (IOC), which is part of UNESCO. In a 17-page summary for policymakers of recent scientific findings, the group concludes that even very large-scale ocean fertilization would remove only modest amounts of carbon dioxide from the atmosphere.
The effects of ocean fertilization have been tested during several experiments carried out over the last decade. Then in 2008, rising concerns over possibly harmful ecological effects saw the Convention on Biological Diversity (CBD) call for a moratorium on all fertilization activities until a global regulatory mechanism was in place.
The UNESCO report, compiled to inform the parties to the London Convention – an international treaty to prevent marine pollution – is now set to be another nail in the coffin of what once seemed a promising way to tackle climate change.
“It’s vastly more complex than assessing carbon storage in a forest,” says Doug Wallace of the Leibniz Institute for Marine Sciences (IFM-GEOMAR) in Kiel, Germany, who chaired the IOC expert group. “The carbon, and many of the potential impacts, are largely invisible and likely to be spread over vast distances.”
Experts are discussing ecosystem impacts ocean fertilization and other proposed geoengineering schemes at a symposium today at the Scripps Institution of Oceanography in La Jolla, California. The symposium can be watched live online.
Image: Iron-induced plankton bloom. Alfred Wegener Institute of Polar and Marine Research.