July 19, 2012
Ocean Fertilization Suffocates Carbon, Reduces Climate Change
Lawrence LeBlond for redOrbit.com - Your Universe Online
The negative impact of climate change might be avoided by dumping massive amounts of iron into the world´s oceans, which smothers carbon dioxide for centuries, according to an international team of researchers who have recently published results of an ocean iron fertilization experiment (EIFEX) carried out in 2004.
The new study, published in the science journal Nature, shows that sowing the ocean with iron particles sucks up and stores CO2, preventing the dangerous greenhouse gas from clogging the atmosphere and further contributing to climate change.
Led by German researchers, the work also showed for the first time that much of the algae that blooms when iron filings are added to the water dies and sinks to the bottom of the ocean. Unlike the LOHAFEX experiment carried out in 2009, EIFEX has shown that a significant amount of carbon from the induced algal bloom sank to the deep sea floor.
But the work, which is closely tied to controversial geo-engineering, came under fire from other scientists and environmentalists, who fear such experiments could adversely affect the marine biosphere.
Geo-engineering, a technology aimed at alleviating global warming, has been criticized sharply not only for the unintended environmental threats that could follow such work, but also for the encouragement of complacency, as governments might be looking for easier ways to get out of their climate deals.
But lead researcher Professor Victor Smetacek, of the Alfred Wegener Institute for Polar and Marine Research (AWI) in Germany, said: “The time has come to differentiate: some geo-engineering techniques are more dangerous than others. Doing nothing is probably the worst option.”
“This represents a whole new ball game in terms of iron fertilization as a geo-engineering technique. Maybe deliberate enhancement of carbon storage in the oceans has more legs than we thought but, as the scientists themselves acknowledge, it's still far too early to run with it,” added Dave Reay, senior lecturer in carbon management at the University of Edinburgh.
Smetacek´s study is one of the biggest and most detailed probes into ocean fertilization to date; and although the practice is banned under international law, scientific research into it is permitted.
In the experiment, the research team added seven tons of iron sulphate to the ocean near Antarctica, where iron levels are generally low. The addition of the iron prompted phytoplankton to begin rapidly growing within a week. And as they began to die after three weeks, they sank to the ocean floor, taking their integrated carbon with them.
The experiment location was chosen carefully, within a 36-mile-wide self-enclosed eddy that acted as a big “test tube.” This allowed the team to monitor the area and compare what happened with the eddy with control points outside the eddy. After a month of monitoring the plankton levels in the eddy, the team found that at least half of the bloom had fallen to depths below 3,200 feet and that a “substantial portion was likely to have reached the sea floor (12,500 ft).”
Based on their findings, the team of scientists conclude that the carbon is likely to be kept out of the atmosphere for many centuries.
Smetacek said more work is needed to see what happens when sideways currents hit the blooms as they fall to the depths.
His team´s results contrast with results from the LOHAFEX experiment in 2009 where phytoplankton growth was limited by different nutrient conditions, especially the absence of dissolved silicon in the chosen eddy. Instead, the plankton bloom consisted of other types of algae which, however, have no protective shell and were eaten more easily by zooplankton.
“This shows how differently communities of organisms can react to the addition of iron in the ocean,” said study co-author Dr. Christine Klaas of AWI.
A 2009 report on geo-engineering by Britain´s Royal Society concluded that ocean fertilization would not suck up that much CO2 and that it would be more harmful to the marine biosphere than it would do good.
“Whilst the new research is an interesting and valuable contribution in this evolving field, it does not address the potential ecological side effects of such a technology in what is a poorly understood field,” Professor John Shepherd, chair of the 2009 landmark report, told AFP´s Richard Ingham in an email.
Canadian-based ETC Group, an environmental non-governmental organization campaigning against geo-engineering, said this study focuses only on a “few narrow aspects and disregards or ignores others. The intended purpose of ocean fertilization is to significantly disrupt marine ecosystems through drastic changes on phytoplankton, which is the base of the marine food web, so the effects would propagate throughout the ocean in unpredictable ways.”
Still, iron plays an important role in the climate system. It is involved in many biochemical processes such as photosynthesis and is essential for biological production in the oceans and, therefore, for CO2 absorption from the atmosphere.
During the past ice ages the air was cooler and drier and more iron-containing dust was transported from land to sea by wind. The iron supply to marine phytoplankton was hence higher during the ice ages. This natural process is simulated in iron fertilization experiments under controlled conditions.
“Such controlled iron fertilization experiments in the ocean enable us to test hypotheses and quantify processes that cannot be studied in laboratory experiments. The results improve our understanding of processes in the ocean relevant to climate change,” said Smetacek. “The controversy surrounding iron fertilization experiments has led to a thorough evaluation of our results before publication,” explaining why there had been such a long delay between the experiment and the current publication in Nature.
“Will this open up the gates to large-scale geo-engineering using ocean fertilization? Likely not, since the logistics of finding the right spot for such experiments are difficult and costly,” noted Michael Steinke, director of marine biology at the University of Essex.
However, responded Smetacek, ocean iron fertilization is much cheaper than other possible geo-engineering techniques.