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.

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.

(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.)

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.

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.

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.