Iron fertilization in the Pacific is not an effective solution to climate change, a new research has revealed.
Experts believed that iron fertilization can cause sporadic growth of algae that absorbs carbon in the ocean. They said more iron means will result in higher algae productivity, thus, increasing the carbon dioxide absorbed from the atmosphere and sank to the sea floor.
However, airborne dust irons in the Pacific did not translate to an increase in algae's ability to absorb carbon dioxide in the atmosphere, said Gisela Winckler, study lead author and a geochemist from Lamont-Doherty Earth Observatory (LDEO) in Columbia University.
In fact, the study correlated that previous iron fertilization in the Pacific have resulted in lower production of algae. Even though iron fertilization conducted in the past have controversial outcomes, it does not suggest that the same findings will be applicable in other areas.
Winckler is presently working with LDEO researcher and co-author Robert Anderson in studying iron dust fertilization and its effects on the Southern Ocean.
Risks Of Iron Fertilization
In 2004, the European Iron Fertilization Experiment (EIFEX) in the Southern Ocean was successful in making algae captured carbon dioxide in their organic tissue.
On the other hand, in 2009, German-Indian Lohafex experiment in the South Atlantic Ocean only resulted in minimal algal bloom, most of which were consumed by marine animals. This has resulted in carbon dioxide going into the food cycle, instead of sinking it.
The Intergovernmental Panel on Climate Change (IPCC) included iron dusts in the climate change alleviation report (PDF), but also warned against its possible negative effects.
The report stated that, while some areas may experience high productivity, downstream marine life may suffer due to low levels of nutrients. Other ill effects of iron dusts include deep ocean acidification, expansion of dead zones with minimal oxygen, but high nitrous oxide, which is more potent that carbon dioxide.
Algae Growth Measurement
The study also referenced the authors' earlier work, which tackled iron dust biological response in the Pacific about 20,000 years ago and expanded the study to include the algae growth from nearly half a million years ago. From there, they concluded that the productivity of the algae did not increase in the five glacial periods.
Cores from deep sea sediments were gathered from three different areas in the equatorial Pacific. The researchers used these to test for barium to establish the level of organic matter that was brought to the ocean floor. The researchers also tested for opal that came from groups of algae. Thorium-232 measurements were also taken to identify the iron dust that came from land.
The authors concluded that the purposeful addition of iron to the water surface of the Pacific will not result in a significant impact on mitigating the effects of atmospheric carbon dioxide.
"While it is well recognized that atmospheric dust plays a significant role in the climate system by changing planetary albedo, the study by Winckler et al, convincingly shows that dust and its associated iron contents is not a key player in regulating the oceanic sequestration of CO2 in the equatorial Pacific on large spatial and temporal scales," said Stephanie Kienast, a marine geologist and paleoceanographer from Dalhousie University, and was not involved in the study.
The study was published in the Proceedings of the National Academy of Sciences on May 16.
