Slowing Global Warming by Enhancing the Natural
Scientists have proposed a limited iron fertilization of the
Southern Ocean as a means to stimulate the natural sulfur cycle
associated with marine phytoplankton. This could result in increased
cloud reflectivity that would slow down global warming and possible
decrease sea level rise.
Socorro, NM (PRWEB) July 24,
2007 -- Prof. Oliver Wingenter of New Mexico Tech and his colleagues
propose a limited iron fertilization of the Southern Ocean as a
means to stimulate the natural sulfur cycle associated with marine
phytoplankton which could result in increased cloud reflectivity
that would slow down global warming and possibly decrease sea level
Wingenter and his research colleagues Dr. Scott M. Elliot at Los
Alamos National Laboratory and Prof. Donald R. Blake at University
of California, Irvine report their research findings in an article
published online July 18 in the journal Atmospheric Environment,
titled "New Directions: Enhancing the natural sulfur cycle to slow
The scientists base their
plan on their observations made during the Southern Ocean Iron
Experiments (SOFeX) research expedition, the longest and most
comprehensive ocean iron fertilization experiment to date, which was
carried out in 2002 aboard three research ships in the Southern
Ocean, between New Zealand and Antarctica.
During the SOFeX, two patches of the Southern Ocean approximately
100 square miles in area each were fertilized with trace amounts of
iron in order to see if an increase in populations of marine,
single-cell algae known as phytoplankton could be used to remove, or
"sink," carbon dioxide---from the atmosphere into the deep ocean.
However, the effectiveness of iron fertilization for sequestering
significant amounts of atmospheric carbon dioxide is still in
"However, marine microorganisms not only consume inorganic
carbon, but also produce and consume many climate-relevant organic
gases," Wingenter continues. "The greatest climate effect of iron
fertilization may be in enhancing dimethyl sulfide (DMS) production,
leading to changes in the optical properties of the atmosphere and
cooling of the region." Samples taken by Wingenter during SOFeX
showed that the concentration of DMS increased about five times in
the iron fertilized patch versus outside. Emissions of DMS are the
main source of sulfate particle formation to the region and "seed"
much of the cloud formation.
Wingenter and his research
colleagues propose a limited fertilization of only about 2 percent
of Southern Ocean---which would result in an estimated two degrees
(Celsius) cooling of the region. A program of limited-scale iron
fertilization in the Southern Ocean and perhaps a portion of the
equatorial Pacific may have the potential to set back the tipping
point of global warming from about 10 years to about 20 or more
years," Wingenter estimates.
An iron-fertilization program of the scale envisioned by
Wingenter and his fellow researchers would require about 30 ships,
fertilizing the Southern Ocean with about 22 kilotons of iron
sulfate, at an annual cost of anywhere between $10 million and $100
million, according to the article in Atmospheric Environment.
Wingenter points out the plan seems doable and can be verified by
satellite observations. He also points out that any unforeseen
consequences would need to be monitored and that the danger is that
policy makers might view proposed geo-engineering solutions an
excuse not to deal with cutting back CO2 emissions.
"Our limited, two percent, fertilization of the Southern Ocean to
enhance the natural sulfur cycle must be differentiated from
previous plans of massive iron enhancements to sequester CO2.
Full-scale iron fertilization of the Southern Ocean must be ruled
out simply because major cooling of the region by increased DMS
would result in a temperature drop of perhaps 10 degrees Celsius or
more," Wingenter says. "Massive fertilization would severely impact
not only the Southern Ocean, but also summertime temperatures and
agriculture in parts of Australia, New Zealand, South Africa, Chile,
Wingenter, Elliot and Blake all received their Ph.D.s at the
University of California, Irvine and were all former graduate
students of the 1995 Nobel Laureate F. Sherwood Rowland.
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