Ocean Fertilization Could Produce Toxic Effects Up the Food Chain

Ideas involving global-scale geoengineering projects aimed at sucking carbon dioxide out of the atmosphere have already faced their share of criticism, but new research on one such idea, ocean iron fertilization, suggests yet another question: Do we want to geoengineer flocks of killer birds run amok — the kind made famous by Alfred Hitchcock?

This is clearly taking things to extremes, but a study published this week in Proceedings of the National Academy of Sciences showed that seeding the ocean with iron results in blooms of tiny organisms called phytoplankton that harbor high levels of a toxin known as domoic acid. Although harmless to the phytoplankton—and in fact, it helps them out-compete other species—domoic acid eventually finds its way into birds and mammals, where it accumulates in the brain and can cause dizziness, disorientation and eventually death.

It has long been speculated that the mass die-off of sea birds that Hitchcock witnessed along the California coast, inspiring his 1963 classic movie, could have been the result of just such a phytoplankton bloom and resultant domoic acid poisoning among the birds.

“I worry about using the ocean as a technical solution for human behavior,” said the study’s lead author, Charles Trick, of the University of Western Ontario. “I think it’s a slippery slope and not a very wise one.”

The idea of iron fertilization as a way of soaking up the excess CO2 in the atmosphere dates from the late 1980s, when oceanographer John Martin famously quipped “Give me a half tanker of iron, and I will give you an ice age.” Adding iron to the ocean can stimulate the rapid bloom of algae, and these tiny organisms can absorb CO2.

Such blooms happen naturally along coastlines, but Trick said it had previously been assumed that the types of organisms present farther out in the open ocean would not build up the toxins after iron fertilization. In his study, which he stressed was a collaboration between several toxicologists and oceanographers, the phytoplankton genus Pseudonitzschia in what are known as high-nitrate, low-cholorophyll waters in the open ocean unexpectedly produced the same high levels of domoic acid seen along shorelines.

“I hope this is just a reminder,” Trick said. “No one is going to die from the toxins formed in these blooms, this is not a human health issue. It really is a scientific and social concern about how we make decisions to solve our problems.”

Opponents of geoengineering schemes point to the immense complexity of ocean and atmospheric systems on the global scale, and that we simply have no way of knowing the way those systems will react to new inputs. This study highlighted one previously discussed concern, in that the Pseudonitzschia organisms absorbed the iron so well that they took it away from other organisms that also need the nutrients.

“Its kind of like iron piracy,” Trick said. “The process actively selects against other species. Its not that they outgrow other species—they actually don’t grow that fast—what happens is they keep the other ones from being able to grow by starving them.”

Still, some think iron is a key part of slowing the steady progress of human-caused climate change. A recent study published in Nature Geoscience indicated for the first time that iron flowing out of undersea volcanoes is responsible for as much as 15 percent of the total carbon storage in the Southern Ocean. This, of course, is a natural process and one that already fits into the global ocean system.

Dan Whaley, the founder and CEO of geoengineering firm Climos, agreed that there remain unanswered questions about ocean fertilization, but to stop trying to answer them is a step in the wrong direction. When faced with the idea that the ocean is too complex to ever understand what might happen if we drastically change it, Whaley said “I think that’s an extremely unscientific point of view. It says that since we can never know the answers, it’s probably not worth even trying to find out.”

Whaley said that geoengineering proponents have asked for, say, one percent of the global climate budget to go toward research and testing of iron fertilization and other ideas like the injection of massive amounts of sulfur dioxide into the atmosphere to cool the planet.

“Do we have sufficient resources to look at multiple aspects of the problem? My argument is that we do,” Whaley said. “Let’s keep doing the research, we’re learning a lot.”

Some large ocean fertilization projects have already been conducted. Last year, the Lohafex collaboration involved seeding a 300 square kilometer area of the Southern Ocean with six tonnes of dissolved iron. The researchers did see increased phytoplankton biomass, but increases in the slightly larger creatures who eat the algae negated much of the effect.

Overall, it appeared to do little to draw excess CO2 out of the atmosphere.

Trick, meanwhile, said that the most recent research on domoic acid just adds to the list of reasons why focusing on geoengineering fixes is simply the wrong way to go.

“It’s not that [the phytoplankton] makes the toxin, per se, it’s that we don’t really understand the consequences of these large-scale fertilizations,” he said. “If we can look for one thing that we think should occur, there is probably a good list of other things that we can’t predict right now that will occur. Let’s not look for a solution that allows us to maintain our high export of CO2 into the atmosphere.”