One of the more controversial geoengineering solutions being researched – ocean fertilization – has met with surprising success. Researchers have found it’s possible to pull carbon dioxide from the atmosphere and sequester it in the ocean floor.
A study published by a team of international researchers in Nature is the first to find that dumping iron in the ocean can indeed transfer carbon from the atmosphere to the ocean floor, where it is buried for centuries.
Iron is a key nutrient for phytoplankton. It stimulates their growth and they absorb carbon during photosynthesis. As their population grows, they absorb more carbon, and when they die, they drop to the ocean floor taking the carbon with them.
In 2004, scientists dumped 7.7 tons of iron sulphate into a 60 square mile area of the Southern Ocean near Antarctica. This year they found that at least half the resulting diatom bloom had sunk below 3,300 feet.
Dozens of previous studies have confirmed that adding iron results in algae blooms, but this is the first to show it sinks to the ocean floor.
"If the 50 percent figure for algal bloom biomass sinking to the deep ocean is correct then this represents a whole new ball game in terms of iron fertilization as a geo-engineering technique," Dave Reay, who lectures on carbon management at the University of Edinburgh (and who wasn’t involved in the study), told Reuters.
If the process works, it could sequester about 10% of current emission totals – about 1 gigaton of carbon a year. It couldn’t store more because phytoplankton growth limited by the amount of phosphorus and nitrogen in the ocean, according to Ken Caldeira, a scientist at the Carnegie Institution.
Scientists don’t yet know what the impact will be on marine life, or whether the carbon that didn’t sink will stay in the upper ocean levels and go back into the atmosphere.
There could be un-intended consequences. Sequestering carbon deep in the ocean floor could actually increase ocean acidity or the dead plankton could pull important nutrients from the ocean ecosystem.
Geoengineering solutions are extremely controversial and many fear the unforeseen consequences of human attempts to control the climate on a large scale. Therefore, large-scale studies of this kind are currently banned by the London Convention which governs dumping at sea.
Other technologies for geoengineering include seeding clouds (mimicking volcanoes), putting great mirrors in space to reflect sunlight away from earth, and carbon capture, which literally pulls carbon out of the atmosphere. Some of the carbon capture techniques are artificial trees, and algae-covered or reflective buildings. The research is being supported by wealthy individuals like Bill Gates and Sir Richard Branson.
With the world barely moving toward halting the progression of climate change, more and more people want this research done to have a back-stop plan.
Out of all of the geoengineering options, this is the most sane. It encourages the growth of plants to permanently store carbon. This is a “natural” mechanism for carbon removal that is responsible removing vast quantities of CO2 during the Ice Ages of recent geologic time.
The unintended consequences of not removing CO2 from the atmosphere are 1000 times scarier than starting intensive research into technologies like this.
The findings that they didn’t mention was that the iron was toxic to diatoms. The Iron sulfate killed the diatoms and caused a green algae bloom. Diatoms float at the surface, when you kill them they stop producing O2 and sink. Since that experiment the Southern Ocean is no longer a carbon sink but gives off more CO2 than it consumes. A company called Planktos also dumped iron into ancient diatom colonies and wiped them out.