Tossing iron powder into ocean to fight global warming

Tossing iron powder into ocean to fight global warming
6 Jan 2009, 2137 hrs IST, Amit Bhattacharya, TNN

NEW DELHI: Can tossing tonnes of iron powder into the ocean help the world fight global warming? A team of Indian scientists, along with their counterparts from Germany and elsewhere, is embarking on an ambitious 70-day ocean expedition on Wednesday to find answers to that question.

Twenty-nine scientists from India, eleven from Germany and ten others will board German research vessel, Polarstern, in Cape Town and head to the experiment site in southwest Atlantic near Antartica. They will stay in the cold and notoriously stormy waters for nearly two months to test a controversial hypothesis that, experts say, has the potential to clean up as much as 1 billion tonne (1 Gt) of CO2 from the atmosphere every year and store it below the ocean for centuries.

CO2 is a greenhouse gas chiefly responsible for global warming. According to current estimates, world emits 7 Gt of carbon into the air every year.

"We hope to have a deeper understanding of the technique than previous researches,'' S W A Naqvi of National Institute of Oceanography, who is the chief Indian scientist for the expedition, told TOI on email from Cape Town.

The experiment, called LOHAFEX loha for iron and FEX for fertilization experiment will test the efficacy of a technique that could not only become the most important way to dispose of CO2, but which also has millions riding on it by way of carbon credits. At least two US companies hope to profit from ‘ocean iron fertilization’ (OIF), as the method is called, by selling credits.

During the $2 million experiment, scientists will throw 20 tonnes of dissolved iron sulphate in 300 sq km of ocean. The iron is expected to stimulate a rapid blooming of phytoplankton, a microscopic algae that grows on the ocean surface.

Like all plants, phytoplankton takes up CO2 from air and converts it to carbon compounds like carbohydrates. The plant quickly dies and starts sinking, taking the carbon with it. What happens thereafter is the key to the technique's efficacy: If it sinks well below the ocean surface, the carbon would effectively have been put away for a long period.

The nutrient-rich but iron-deficient southern ocean is seen as an ideal site for OIF. The area is spread across 50 million sq km 15 times the size of India. The math done by scientists show that if the entire southern ocean were fertilized by iron and a sizeable fraction of the phytoplankton sank well below 1,000m, then about 1 Gt of carbon would be isolated for centuries. Water at depths below 500m takes about 100 years to come to the surface.

The scientists say the carbon footprint - additional carbon emitted by the technique - would be minor as compared with the gains.

For seven weeks, LOHAFEX's team of physicists, chemists, biologists and geochemists will study the effects of the algal bloom on the exchange of CO2 between ocean and atmosphere as well as on the oceanic food chain and the organisms of the underlying sea floor.

As Prof Naqvi put it, "The core issue the fate of organic matter produced due to iron fertilization is still not settled. It is not clear whether this material gets recycled in the near-surface layer (which would make OIF not very useful) or a substantial fraction of it gets transported to the deep sea (which will make OIF a useful technique to isolate CO2). LOHAFEX is better equipped to track the fate of this carbon than previous researches.''

The researchers will also study krill, a shrimp-like animal which feeds on phytoplankton and is the main food of Antarctic penguins, seals and whales. Krill stocks have declined by over 80% in past decades and their response to the iron-fertilized bloom could give clues to help in recovery of the decimated great whale populations as well.

"India hasn't carried out such an experiment in the ocean so far. It requires a high level of expertise not found elsewhere in the Third World. So, apart from the scientific gains, the experiment itself should enhance our prestige. Significantly, more than half the Indian participants are students (from NIO),'' Naqvi said.

But OIF remains controversial, with many environmentalists saying it amounts to major tinkering with the marine eco-system. If done on the scales proposed in the future, it could have unforeseen consequences, they warn.