Iron fertilization: Scientists want to add the element to the ocean to capture carbon

The climate is warming, and much of the increase is due to greenhouse gases, the most prevalent gas being carbon dioxide. Methods for removing existing carbon from the atmosphere are in the works, and some experts are arguing in favor of iron fertilization, a geoengineering approach which would help oceans trap atmospheric carbon. While the method has potential, the consequences of implementing it are still largely unknown.

Iron in the ocean

An article published in the journal Frontiers in Climate lays out a program for implementing iron fertilization to help fight climate change. Ocean iron fertilization (OIF) is a "technique where small amounts of micronutrient iron are released onto the surface of the sea to stimulate the growth of marine plants known as phytoplankton," said Euronews. "This rapid growth removes carbon dioxide from the atmosphere through photosynthesis. When the plankton die or are eaten, some of that carbon is captured as it sinks deep into the ocean." Geoengineering like OIF has long been in discussion as a way to mitigate carbon emissions.

"Given the ocean's large capacity for carbon storage … enhancing the ocean's natural ability to store carbon should be considered," Paul Morris, one of the authors of the study and the project manager for international experts group Exploring Ocean Iron Solutions (ExOIS), said in a statement. ExOIS wants to conduct iron fertilization trials to determine whether the technology could be implemented on a larger scale. "This is the first time in over a decade that the marine scientific community has come together to endorse a specific research plan for ocean iron," Ken Buesseler, the study's lead author and executive director of the ExOIS project, said in the statement. The program wants to raise $160 million for the trial and has already received a $2 million grant from the National Oceanic and Atmospheric Administration.

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Oceanic objections

Not everyone is on board with investing in iron fertilization. Many worry that "fertilization could create 'dead zones' where rampant algal blooms would consume all the oxygen in the water, snuffing out other life," said Scientific American. "Phytoplankton blooms could also consume nutrients such as phosphorus and nitrogen that then wouldn't be available for organisms elsewhere, a phenomenon known as 'nutrient robbing.'" There is little known about how iron fertilization will interact with other climate factors that affect marine life, like warming oceans.

In addition, iron fertilization may not be as effective at removing carbon as some experts claim. "Even at its peak performance, the technique just can't store that much carbon," Alessandro Tagliabue, an ocean biogeochemist at the University of Liverpool, said to Hakai Magazine. "Setting up a large-scale nutrient fertilization project would require mining the minerals and building infrastructure to get them into the ocean. These activities would emit carbon, lowering the overall carbon sequestration potential by the time the nutrients hit the water."

However, some sacrifices could be necessary to ensure progress. "It's a small change in biology, relative to doing nothing and watching this planet boil," Buesseler said to Scientific American.