Part 2. Exploring Scientific Evidence and
Evaluating Choices
Section 7: Advanced details on the "Iron
Solution"
The "Iron Solution"
The global oceans contain a rich abundance of plant life which is a major user of carbon dioxide from the atmosphere. Phytoplankton are tiny single-celled ocean plants containing the chemical chlorophyll that use sunlight and carbon dioxide to create plant carbon. This plant carbon then becomes food for small fish and other marine life.For advanced information on the ocean portion of the carbon cycle, click on any of the links below:
Life in
the Oceans: Studying Global Ocean Color from Space (SeaWiFS)
Oceans and the carbon cycle
(UNEP)
Phytoplankton: A Little Link in a Big Chain (SeaWiFS)
The
Ocean Isn't Just Blue: What we See from Space (SeaWiFS)
Photosynthesis: How Plants Make Food
(Dr. Earl Fleck, Biology Department, Whitman
College)
Carbon:
Where Does It All Go? (SeaWiFS)
John H. Martin, R. Michael Gordon, and Steve E. Fitzwater of Moss Landing Marine Laboratory, CA proposed (Nature 345, 156-158, 10 May 1990) that it might be possible to remove excess carbon dioxide from the atmosphere by using iron fertilizer to stimulate growth of phytoplankton in specific regions of the polar oceans. The authors measured the concentrations of essential nutrients for phytoplankton in oceans around Antarctica and found that adequate amounts of phosphate, nitrate, and silicate exist to support abundant blooms of algae in these regions. However, they found the waters in the Drake Passage separating South America and Antarctica to be significantly deficient in iron. The result is that far lower concentrations of phytoplankton exist in this area. Adding a solution containing iron to surface waters in this area could possibly increase phytoplankton abundance by a factor of 10 or more. And larger concentrations of phytoplankton would take carbon dioxide from the atmosphere and turn it into plant carbon for consumption by small fish at the bottom of the food chain.
Iron-rich sediments in coastal waters, together with upwelling coastal currents, normally supply sufficient amounts of iron for algae growth at the ocean surface near coastal areas in the spring and summer when abundant solar energy is available (see, for example, the polar oceans in the image below.)
(Adapted from
of SeaWiFS Project, NASA)
Regions far from the a continental coast normally get iron from a second source, namely in the form of dust settling from the atmosphere. A third source of iron in the Antarctic region is the melting of sea ice. The Drake Passage, however, has insufficient coastal upwelling, lack of melting sea ice and an unusually pristine atmosphere that has very little atmospheric dust. Therefore phytoplankton concentration in surface water is far lower than it could be if this essential nutrient were available.
The authors conclude that by adding iron to the surface
waters in the Drake Passage, phytoplankton would flourish and
capture large amounts of carbon dioxide from the atmosphere.
This, in turn, would reduce the greenhouse effect
and suppress the rate of global warming. For additional information see
The Earth is unique to our solar system: it can sustain life from
the SeaWiFS Project
Click here to
return to Part 2, section 7: Engineered solutions
Continue to Part
2, section 8