The results of the latest iron fertilization experiment in the Southern Ocean are in – and it doesn’t look good as a solution for climate change. The Lohafex project, a collaboration between Indian and German scientists, found that merely stimulating a plankton bloom with iron did not lead to carbon sequestration.
What they were hoping would happen was this:
- Iron input
- Diatom bloom – diatoms have fast-sinking silica shells
- Diatoms die & sink to bottom
- Silica shells buried for all eternity
- Carbon sequestration WIN!
What actually happened was this:
- Iron input
- Yummy Phaeocystis algae bloom – no silica shells
- Copepods (tiny crustaceans) eat delicious soft algae.
- Amphipods (small crustaceans) eat delicious crunchy copepods.
- Copepods and amphipods respire, turning the algae right back into carbon dioxide.
- Carbon sequestration LOSE.
Previous studies have shown that only 1-2% of sinking carbon (and that’s a generous estimate) gets sequestered. There’s life in the deep midwater and life in the deep sea and all life is HUNGRY. (Personally, I blame the deep-sea sea cucumbers – those gluttons are major consumers of what little detritus makes it down there.)
Though the iron fertilization part of this cruise didn’t work out as desired, understanding nutrient cycling and plankton dynamics in the Southern Ocean is really important. As the polar ice melts it could cause nutrients to fluctuate, affecting the whales and squid and birds that all depend on Antarctic food sources. So please count me in for any future collaborations with Indian scientists! From the press release:
Spicy Indian curries were prepared at each meal by a Goan cook specially engaged for this cruise and contributed to the good atmosphere.