Part 2. Exploring Scientific Evidence and
Evaluating Choices
Section 7: Advanced details on the "Iron
Solution"
Physical limitations
Peng and Broecker {Nature, 349, 227-229 ( 17 January 1991)} further explore the iron solution to global warming proposed by Martin. They considered how the carbon dioxide captured by phytoplankton would be moved away from the surface to allow for the continuing capture of more carbon dioxide. Carbon captured at the surface is moved by the slow vertical circulations of the polar ocean. (See How the oceans influence climate from UNEP.) Detailed calculations by the authors revealed that this circulation is so slow that carbon cannot be carried away from the surface fast enough to take full advantage of the phytoplankton capture mechanism at the surface. They estimate that the atmospheric concentration of carbon dioxide would be reduced by 34 ppm if the polar ocean was fertilized continuously for a 100 year period. If the fertilization program was terminated, the carbon dioxide capturing process would fade away at about the same rate it was established when the iron was added.The authors conclude that the ocean transport rate is the factor that limits the effectiveness of the proposed iron solution, and that the amount of reduction over 100 years is quite small compared to the level of build-up due to burning fossil fuels and deforestation.
Click here to
return to Part 2, section 7: Engineered solutions
Continue to Part
2, section 8