Scientists find ocean fertilization won't work - final blow to controversial geoengineering option

Scientists have revealed an important discovery that raises serious doubts concerning the viability of plans to fertilize the ocean to solve global warming, a projected $100 billion 'geoengineering' venture that has attracted a lot of criticism from environmentalists, climate scientists, civil society and oceanographers who think the scheme may destroy marine environments. The concept was recently deemed 'not scientifically justified' by the International Maritime Organisation (IMO) (earlier post). The bioenergy community for its part is opposed to the idea, because it distracts attention from a much safer solution to global warming, namely the production of negative emissions from bioenergy. But now scientists deal the final blow to the controversial concept, saying it simply won't work.

Ocean fertilization, the process of adding iron or other nutrients to the ocean to cause large algal blooms, has been proposed as a possible 'geoengineering' solution to global warming because the growing algae absorb carbon dioxide as they grow. But research performed at Stanford University, the Carnegie Institution of Washington and Oregon State University, published in the Journal of Geophysical Research, now concludes that ocean fertilization is not an effective method of reducing CO2 in the atmosphere because of the seasonal dynamics of the way in which algae sink to the bottom of the ocean.

This technique of ocean fertilization, which is analogous to adding fertilizer to a lawn to help the grass grow, only reduces carbon dioxide in the atmosphere if the carbon incorporated into the algae sinks to deeper waters. This process, which scientists call the 'Biological Pump' (image, click to enlarge), has been thought to be dependent on the abundance of algae in the top layers of the ocean. The more algae in a bloom, the more carbon is transported, or 'pumped', from the atmosphere to the deep ocean.

To test this theory, researchers compared the abundance of algae in the surface waters of the world's oceans with the amount of carbon actually sinking to deep water. They found clear seasonal patterns in both algal abundance and carbon sinking rates. However, the relationship between the two was surprising: less carbon was transported to deep water during a summertime bloom than during the rest of the year. This analysis has never been done before and required designing specialized mathematical algorithms. By jumping a mathematical hurdle the scientists found a new globally synchronous signal.

This discovery is very surprising. If, during natural plankton blooms, less carbon actually sinks to deep water than during the rest of the year, then it suggests that the Biological Pump leaks. More material is recycled in shallow water and less sinks to depth, which makes sense if you consider how this ecosystem has evolved in a way to minimize loss. Ocean fertilization schemes, which resemble an artificial summer, may not remove as much carbon dioxide from the atmosphere as has been suggested because they ignore the natural processes revealed by this research. - Dr. Michael Lutz, lead author, University of Miami's Rosenstiel School of Marine and Atmospheric Science

The global study of Dr. Lutz and colleagues suggests that greatly enhanced carbon sequestration should not be expected no matter the location or duration of proposed large-scale ocean fertilization experiments.

According to the researchers, the limited duration of previous ocean fertilization experiments may not be why carbon sequestration wasn't found during those artificial blooms. This apparent puzzle could actually reflect how marine ecosystems naturally handle blooms and agrees with our findings. A bloom is like ringing the marine ecosystem dinner bell. The microbial and food web dinner guests appear and consume most of the fresh algal food:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: climate change :: ocean fertilisation :: carbon dioxide :: algae :: bioenergy with carbon storage :: negative emissions :: geoengineering ::

The study highlights the need to understand natural ecosystem processes, especially in a world where change is occurring so rapidly, concluded Dr. Lutz.

This study closely follows a September Ocean Iron Fertilization symposium at the Woods Hole Oceanographic Institution (WHOI) attended by leading scientists, international lawyers, policy makers, and concerned representatives from government, business, academia and environmental organizations.

Topics discussed included potential environmental dangers, economic implications, and the uncertain effectiveness of ocean fertilization. To date none of the major ocean fertilization experiments have verified that a significant amount of deep ocean carbon sequestration occurs:

Some scientists have suggested that verification may require more massive and more permanent experiments. Together with commercial operators they plan to go ahead with large-scale and more permanent ocean fertilization experiments and note that potential negative environmental consequences must be balanced against the harm expected due to ignoring climate change.

During the Ocean Iron Fertilization meeting Dr. Hauke Kite-Powell, of the Marine Policy Center at WHOI, estimated the possible future value of ocean fertilization at $100 billion of the emerging international carbon trading market, which has the goal of mitigating global warming. However, according to Professor Rosemary Rayfuse, an expert in International Law and the Law of the Sea at the University of New South Wales, Australia, who also attended the Woods Hole meeting, ocean fertilization projects are not currently approved under any carbon credit regulatory scheme and the sale of offsets or credits from ocean fertilization on the unregulated voluntary markets is basically nothing short of fraudulent.

There are too many scientific uncertainties relating both to the efficacy of ocean fertilization and its possible environmental side effects that need to be resolved before even larger experiments should be considered, let alone the process commercialized. All States have an obligation to protect and preserve the marine environment and to ensure that all activities carried out under their jurisdiction and control, including marine scientific research and commercial ocean fertilization activities do not cause pollution. Ocean fertilization is 'dumping' which is essentially prohibited under the law of the sea. There is no point trying to ameliorate the effects of climate change by destroying the oceans - the very cradle of life on earth. Simply doing more and bigger of that which has already been demonstrated to be ineffective and potentially more harmful than good is counter-intuitive at best. - Professor Rosemary Rayfuse, University of New South Wales

The findings of Dr. Lutz and colleagues coincide with and affirm this month's decision of the London Convention (the International Maritime Organization body that oversees the dumping of wastes and other matter at sea) to regulate controversial commercial ocean fertilization schemes. This gathering of international maritime parties advised that such schemes are currently not scientifically justified.

Strategies to sequester atmospheric carbon dioxide, including the enhancement of biological sinks through processes such as ocean fertilization, will be considered by international governmental representatives during the thirteenth United Nations Framework Convention on Climate Change conference in Bali next month.

Virtually all of the radical geoengineering options proposed so far have been rejected for being too risky. These include emulating volcanoes' cooling effects by pumping sulphur into the atmosphere (debunked as outright dangerous to the planet - earlier post), creating a giant space mirror (which would be prohibitively costly), or generating highly reflective clouds (more here). Most of these proposals have been simulated and some have been shown to be full of uncertainties and hence generate a high number of risks (previous post). Other, safer proposals have been found to be too costly (a recent example).


One of the only geoengineering proposals seen as economically viable, environmentally safe and efficient, is the production of carbon-negative bioenergy. By planting biomass (trees, energy crops), and utilising them as feedstocks for energy production to replace fossil fuels, a 'carbon-neutral' form of energy is obtained. But when the CO2 that is released into the atmosphere during this process is captured and locked up - either in geological formations or in soils - then carbon-negative energy and fuels can be generated. Scientists have found that, when implemented on a planetary scale (hence 'geoengineering'), such negative emissions energy systems can take us back to pre-industrial atmospheric CO2 levels by mid century (previous post, here and here).

These 'bio-energy with carbon storage' (BECS) systems are currently becoming the object of more attention in the energy and climate change community. With these systems it becomes possible to take historic CO2 emissions back out of the atmosphere. Other renewables, like wind or solar energy, are 'carbon neutral' at best (schematic, click to enlarge). That is, they do not add new emissions to the atmosphere. But BECS systems go much further: they actually take carbon dioxide emissions from the past out of the carbon cycle, thus radically tackling the main cause of climate change. Now that we are facing the potential doom scenario of 'abrupt climate change', negative emissions bioenergy will have to be promoted.

References:
Michael J. Lutz, Ken Caldeira, Robert B. Dunbar, Michael J. Behrenfeld, "Seasonal rhythms of net primary production and particulate organic carbon flux to depth describe the efficiency of biological pump in the global ocean", Journal of Geophysical Research, Vol. 112, 2007, C10011, doi:10.1029/2006JC003706.

Eurekalert: New research discredits $100B global warming 'fix' - November 29, 2007.

Biopact: International maritime body rejects risky ocean geoengineering - November 09, 2007

Biopact: The end of a utopian idea: iron-seeding the oceans to capture carbon won't work - April 26, 2007

Biopact: WWF condemns Planktos Inc. iron-seeding plan in the Galapagos - June 27, 2007

Bioapct: Scientists propose new geoengineering option: increasing ocean's alkalinity to soak up more carbon dioxide - November 19, 2007

Biopact: IPCC to warn of 'abrupt' climate change: emergency case for carbon-negative biofuels kicks in - November 16, 2007

Biopact: Scientists propose artificial trees to scrub CO2 out of the atmosphere - but the real thing could be smarter - October 04, 2007

Biopact: A quick look at 'fourth generation' biofuels - October 08, 2007