Let’s Pump Some Iron

It’s the solution to climate change we’ve been searching for! Every new green technology solution touts that claim, right? Well, Reuters recently reported that ocean iron fertilization could be the answer to our climate woes. Is that true?

First, what is ocean iron fertilization (referred to as OIF)? Basically, some scientists propose adding large amounts of iron particles to the ocean’s surface, which will spur the growth of microscopic phytoplankton blooms (a type of tiny algae). These blooms absorb carbon from the atmosphere during their lifespan of 90-120 days and then carry much of that carbon with them to the lower ocean after the blooms die, effectively removing that carbon from the atmosphere and the carbon cycle.

This makes sense in theory, but does it actually work outside the lab? The London Convention currently bans large-scale tests in the open ocean, but tests performed before the ban indicate that OIF could work. In 2004, a group of scientists added 7 tons of iron sulphite into the Southern Ocean, and at least half of the carbon absorbed by the phytoplankton blooms sank to below 1,000 meters. Some were concerned that the blooms would absorb carbon but would remain in the upper ocean where the carbon could easily be absorbed back into the atmosphere. But, it appears that a significant portion of the blooms would, in fact, sink to the lower ocean. Here, the carbon can remain sequestered for centuries. (My question: would it then eventually be released from the blooms and return back to the atmosphere, causing a problem further down the road?)

Tests were also performed near the Galapagos Islands in 1993 and 1995 based upon John Martin’s iron hypothesis. In the first test, 1,000 pounds of iron was deposited into the ocean, and chlorophyll levels rose to three times their normal level within 9 days (as you can imagine, higher chlorophyll levels mean that more phytoplankton can bloom). In the 1995 test, multiple rounds of iron were introduced over several days, and the water showed a chlorophyll level 30 times higher than normal. Diatoms (a type of phytoplankton) grew at 85 times their normal rate, and the resulting blooms absorbed an estimated 367 tons of carbon dioxide (all within 3-4 months). It would take approximately 100 years for one acre of tree to absorb that amount of carbon. Wow!

Despite these convincing results, there is a great deal of debate surrounding OIF. Major concerns include:

  1. The possibility of an increase in harmful algal blooms that result in red tides or dead zones.  But, scientists point out that they know how to avoid the growth of harmful algae. Additionally, OIF would take place in the open ocean, and the short lifespan of the phytoplankton blooms (90-120 days) would prevent them from reaching land. Because coastal areas are already rich in iron, any iron that reaches the shore would likely have no effect.
  2. The theory that increased iron concentrations may lead to an increase in emissions of nitrous oxides, another harmful greenhouse gas.
  3. The disturbance of the ocean’s ecosystem by favoring the growth of certain species. However, many scientists argue that increased phytoplankton growths aren’t expected to have any deleterious effects. In fact, these growths could feed small fish, like krill, which theoretically could increase supply throughout the food chain.

As you can see, many of the concerns above are refutable. Plus, scientists have pointed out a few additional benefits of OIF, including:

  1. Phytoplankton blooms help remove carbon dioxide from the atmosphere. Most current efforts aim to reduce the amount of carbon being emitted, but that still does not increase the overall carbon concentration in the atmosphere.
  2. Many phytoplankton release dimethylsulfide (DMS) into the atmosphere, which could have an aerosol effect – reflecting some of the sun’s incoming rays and subsequently counteracting warming.
  3. Global iron fertilization is estimated to cost only $20 billion, which works out to less than 0.3% of the 2011 global economy.

The biggest concern with OIF is that it involves tampering with the environment. OIF is a form of geo-engineering. But, John Martin argued that iron-rich dust from Earth’s continents blew into the ocean in large quantities, increasing phytoplankton growth, and contributing to the Ice Age. Can OIF then be viewed as facilitating a natural process?

I think that OIF has a huge amount of potential to help combat climate change. But, I do think more research is necessary before we can implement it on a large scale. Altering the Earth’s natural state can have unknown consequences, as we have seen. So, it is important to better understand any risks of OIF before diving in (pun intended).


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