The idea behind iron fertilization as a form of geoengineering is this: organisms in the ocean often have a rate of growth that is confined by the availability of a single nutrient. It’s like assembling laptops when there is only a limited amount of silicon around for processors. No matter how many cases, keyboards, and screens you can build, you can’t make finished laptops until you get more silicon. Since iron is often a growth-limiting nutrient in the ocean, the hope is that humans could add it to the sea, causing a bloom in ocean plant life. Those living things would draw carbon dioxide (CO2) from the atmosphere and then, hopefully, sink to the bottom of the sea and keep the carbon trapped there for a long time.
Recently, scientists tried adding six tonnes of iron to the Southern Ocean, around Antarctica. The idea was to test whether such an approach could help draw down the level of CO2 in the atmosphere. As reported by the BBC, the experiment was not very successful. They quote Victor Smetacek as saying:
There’s been hope that one could remove some of the excess carbon dioxide – put it back where it came from, in a sense, because the petroleum we’re burning was originally made by the algae. But our results show this is going to be a small amount, almost negligible.
Basically, the problem seems to be that the algae get eaten by animals near the surface, rather than sinking undigested to the cold ocean floor. That means the carbon remains within the Earth’s physical and biological cycles, rather than sinking down to where it won’t have medium-term effects. It may be that fertilization experiments in other locations, or with other nutrients, prove more successful.
Some odd game theory surrounds geoengineering. One possibility is that no type of geoengineering will not work at all. Another is that it might lower temperatures, but have unacceptable other effects. People also worry that the very possibility of geoengineering makes policy-makers more reckless, since they see it as a possible long-term solution that eliminates the need to reduce emissions. From an environmental standpoint, it would be useful to know that geoengineering certainly would not work, since it would help avoid a dead-end technology and would make it even more clear that emissions must be sharply reduced. That being said, it may be environmentally harmful to learn that it is possible, especially if the harmful consequences will mostly be borne by people living in poor states with relatively low greenhouse gas emissions. Powerful states may be tempted to geoengineer their way out of the climate problem, even if the consequences for those in other parts of the world are appalling. Given how appalling the consequences of our greenhouse gas emissions are likely to be for future generations within our own states, it would not be surprising if voters and governments opt for such a negligent course of action. The fact that we are cheerfully committing suicide suggests that we will probably commit murder without the slightest concern or consideration. Of course, knowing that geoengineering is possible would give us one last desperate option, in the event that abrupt and catastrophic climate change begins.
As it stands, the world simply isn’t coordinated enough to prevent any research into geoengineering. All we can do is fight to ensure the information and techniques that are acquired be used in a responsible way: taking into account the welfare of people around the world, in both this generation and those that will follow.
Timescales are an issue here. The effects of geoengineering would likely be felt much more quickly than the full effects of climate change.
Given how appalling the consequences of our greenhouse gas emissions are likely to be for future generations within our own states, it would not be surprising if voters and governments opt for such a negligent course of action. The fact that we are cheerfully committing suicide suggests that we will probably commit murder without the slightest concern or consideration.
Those alive today aren’t really risking suicide by climate change, though the national policies of many states are likely to be suicidal for those states. It is fairer to say that those alive in states like Canada now are risking the deaths of those who will live in Canada later. In the nearer term, their possibility of living prosperous and satisfying lives is being threatened.
Also, since geoengineering would happen on a year-to-year timescale, people in affected states and regions could complain while it was going on. Obviously, members of future generations that will be badly harmed by climate change can neither speak to us now nor do anything to stop our climate destabilizing activities.
This is true enough, and an important moral point to stress:
To a considerable extent, the welfare (perhaps even the lives) of those in future generations is dependent on the choices we make, regarding our emissions. At the same time, they are powerless to harm us in any way.
Hungry Crustaceans Eat Climate Change Experiment
Earlier this month, an expedition fertilized 300 square kilometers of the Atlantic Ocean with six metric tons of dissolved iron. This triggered a bloom of phytoplankton, which doubled their biomass within two weeks by taking in carbon dioxide from the seawater. The dead phytoplankton were then expected to sink to the ocean bed, dragging carbon along with them. Instead they experiment turned into an example of how the food chain works as the bloom was eaten by a swarm of hungry copepods. The huge swarm of copepods were in turn eaten by larger crustaceans called amphipods, which are often eaten by squid and whales. “I think we are seeing the last gasps of ocean iron fertilization as a carbon storage strategy,” says Ken Caldeira of the Carnegie Institution at Stanford University. While the experiment failed to show ocean fertilization as a viable carbon storage strategy, it has pushed the old “My dog ate my homework” excuse to an unprecedented level.
Adding iron into the oceans, to induce a phytoplankton bloom that will take up atmospheric CO2, is one of the many proposed geo-engineering solutions to slow down climate change. Some perspective on such an approach is provided by research conducted by an international team of scientists in a region of the southern ocean where there is a natural source of iron enrichment. Specifically, the scientists tested the hypothesis that the observed north-south gradient in phytoplankton concentrations is induced by natural iron fertilization (in which iron-rich dust blowing off the Crozet Islands settles on the waters) and that the areas of higher concentration have enhanced organic carbon flux into the deep ocean. Their observations indicate that natural iron fertilization does enhance new phytoplankton production and does lead to higher export of carbon into the ocean. At 100 metres depth, there was a two- to threefold increase in carbon export compared to an adjacent high nutrient, low-chlorophyll area not fertilized by iron. Moreover, the carbon fluxes at 3000 metres were similarly two to three times higher beneath the iron fertilized region. These results support an earlier hypothesis that increased iron supply to the glacial sub-Antarctic enhances carbon sequestration into the deep ocean. However, comparing their results with previous experimental studies, they found that carbon sequestration efficiency was 18 times greater than that of a phytoplankton bloom induced artificially by adding iron. The authors note that the large losses of iron during artificial iron enrichment experiments can explain the lower efficiency of the induced bloom. These results have significant implications for proposals to mitigate the effects of climate change through purposeful addition of iron to the ocean since they indicate that such approaches may not be very efficient.
(Reference: Pollard, R.T, I. Salter, R.J. Sanders et al. 2008. Southern Ocean deep-water carbon export enhanced by natural iron fertilization. Nature, 457, doi:10.1038/nature07716, 5 pages.)
Can you explain the iron hypothesis in terms of a car analogy?
Nature: Ocean fertilization for geoengineering “should be abandoned”
By Joe on Geoengineering
In the face of seemingly accelerating climate change, some have proposed tackling the problem with geoengineering: intentionally altering the planet’s physical or biological systems to counteract global warming. One such strategy — fertilizing the oceans with iron to stimulate phytoplankton blooms, absorb carbon dioxide from the atmosphere and export carbon to the deep sea — should be abandoned.
Climate ‘fix’ could poison sea life
By Richard Black
Environment correspondent, BBC News
Fertilising the oceans with iron to absorb carbon dioxide could increase concentrations of a chemical that can kill marine mammals, a study has found.
Iron stimulates growth of marine algae that absorb CO2 from the air, and has been touted as a “climate fix”.
Now researchers have shown that the algae increase production of a nerve poison that can kill mammals and birds.
Writing in Proceedings of the National Academy of Sciences, they say this raises “serious concern” over the idea.
The toxin – domoic acid – first came to notice in the late 1980s as the cause of amnesiac shellfish poisoning.
It is produced by algae of the genus Pseudonitzschia, with concentrations rising rapidly when the algae “bloom”.
Now, its presence in seawater often requires the suspension of shellfishing operations, and is regularly implicated in deaths of animals such as sealions.
Domoic acid poisoning may also lie behind a 1961 incident in which flocks of seabirds appeared to attack the Californian town of Capitola – an event believed to have shaped Alfred Hitchcock’s interpretation of Daphne du Maurier’s The Birds in his 1963 thriller.
Controversial Spewed Iron Experiment Succeeds as Carbon Sink
Dumping iron into the ocean stimulates blooms of diatoms that pull down carbon dioxide in the atmosphere–but only under the right conditions
Dumping iron at sea can bury carbon for centuries, study shows
Iron fertilisation creates algae blooms that later die off and sink, taking the absorbed carbon deep towards the ocean floor