Oct 8, 2009 11:56 AM
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Scientists commissioned to track the effects of the Sydney dust storm have found something intriguing - a massive growth spurt in nearby ocean algae growth, which could help counteract global warming. Could the storm be proof-of-concept for geoengineering the oceans?
The dust storm accomplished something that geoengineers call "ocean fertilization." When the storm hit Sydney, it dumped an estimated three million tonnes of Australian desert dust into Sydney Harbour and the Tasman Straight. That dust brought nitrogen and phosphate to the waters, providing food to microscopic phytoplankton, whose population numbers rapidly tripled (which is what you see in the image above). And that in turn may rapidly expand the population of local fish, too. Boosting the lower levels of the food chain can easily lead to population growth at the higher rungs.
But ocean fertilization isn't just a way to help the fishing industry, and feed hungry Australians. There are some even more interesting results that come from rapidly hurling piles of dirt into the ocean - results that could slow climate change.
Ocean fertilization can trap atmospheric carbon. First, the excess algae absorb carbon dioxide; then, when the algae dies and sinks to the bottom of the ocean, the carbon it has absorbed is isolated from the atmosphere for a few thousand years. Of course, the effectiveness of this is hotly disputed. An article recently published in Nature tracked a natural influx of high levels of iron into the ocean around the Crozet Islands, and the carbon uptake was 50 times lower than previously estimated. This study, as most others on the subject, focused on iron rather than nitrogen, and there is some argument that natural intake will produce different effects than deliberately dumping tonnes of the material into the ocean. Geoengineering could promote different phytoplanktons to develop. The location of the experiment also has a lot to do with what grows and how much carbon it traps.
The final effect that this explosion of algae could produce? It could help cool the planet. Certain plankton species produce dimethyl sulfide, which works its way into the atmosphere, and eventually transforms into clouds, increasing the reflectivity of the Earth, and lowering its temperature.
So, by taking tonnes of desert dirt (something Australia is in no way short of), and flushing it into the ocean, we can potentially rejuvenate flagging fish populations, trap atmospheric carbon dioxide and lower the Earth's albedo. That's a hell of a way to hack the planet. Except no-one's sure if it actually works yet, with iron or nitrogen.
Now Australian geoengineers Ian Jones and Associate Professor Rob Wheen, both of Sydney University, want to inject 2.5 tonnes of nitrogen-rich urea into a controlled area of the sea and try to replicate the effect. They claim that nourishing a 20km wide patch of water could significantly boost catch numbers for small-scale artisanal fishing industries.
The process still very controversial, and the act of massively changing the makeup of the biosphere is practically begging for algae to take over the ocean as we know it and start belching sulfurous fumes into the air. Jones is also the head of the Ocean Nourishment Corporation, a private group who are attempting to use urea to boost phytoplankton numbers, and gain carbon credits to sell, which perhaps makes him a less than unbiased figure to ask about the whole topic.
Still, the Sydney dust storms have given us the first solid evidence that ocean nourishment can affect algae blooms. And as far as geoengineering goes, ocean fertilization uses techniques and technology readily available. If the mechanisms of action are shown to be effective, Jones and Wheen's project could be rolled out easily. The research on it is already underway, and it's now a working concept. Your oceans could be massively reengineered soon, without requiring significant hardware developments.
Dust storm triggers ocean bloom [ABC Science]
Send an email to Tim Barribeau, the author of this post, at tim@io9.com.
Original material is licensed under a Creative Commons License permitting non-commercial sharing with attribution.
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