Stimulating phytoplankton could backfire
By Summit Voice
One of the ideas that has surfaced most often is adding certain types of nutrients to the oceans to stimulate algae production in the hopes of reducing CO2. But new research shows that the law of unintended consequences always applies, perhaps even more so when experimenting with climate on a global scale.
The new study on the feeding habits of ocean microbes shows that the idea could backfire by disturbing the natural balance of ocean chemistry. After carefully studying diatoms, one type of plankton, the scientists determined that it is uses more iron that it needs for photosynthesis and storing the extra in its silica skeletons and shells. This reduces the amount of iron left over to support the carbon-eating plankton.
“Just like someone walking through a buffet line who takes the last two pieces of cake, even though they know they’ll only eat one, they’re hogging the food,” said Ellery Ingall, a professor at the Georgia Institute of Technology and co-lead author on this result. “Everyone else in line gets nothing; the person’s decision affects these other people.”
Because of this iron-hogging behavior, the process of adding iron to surface water – called iron fertilization or iron seeding – may have only a short-lived environmental benefit. And, the process may actually reduce over the long-term how much C02 the ocean can trap.
Rather than feed the growth of extra plankton, triggering algal blooms, the iron fertilization may instead stimulate the gluttonous diatoms to take up even more iron to build larger shells. When the shells get large enough, they sink to the ocean floor, sequestering the iron and starving off the diatom’s plankton peers.
Over time, this reduction in the amount of iron in surface waters could trigger the growth of microbial populations that require less iron for nutrients, reducing the amount of phytoplankton blooms available to take in C02 and to feed marine life.
The work was supported by the National Science Foundation and the Swedish Antarctic Research Programme. The U.S. Department of Energy’s Office of Basic Energy Sciences supported use of the APS.The research was conducted by Ingall, Julia Diaz, Amelia Longo and Michelle Oakes from the Georgia Institute of Technology; Lydia Finney, Stefan Vogt and Barry Lai from the Advanced Photon Source; Patricia Yager from the University of Georgia; Benjamin Twining from the Bigelow Laboratory for Ocean Sciences; and Jay Brandes from the Woods Hole Oceanographic Institution.
Filed under: climate and weather, Environment, global warming Tagged: | climate, CO2, Geoengineering, Georgia Institute of Technology, Iron fertilization, National Science Foundation, ocean seeding, oceans, Southern Ocean, University of Georgia, Woods Hole Oceanographic Institution