Geoscience Reference
In-Depth Information
environmental groups. The team's research
vessel dumped six tons of dissolved iron in
a 300- square- kilometer (115- square- mile)
patch of the ocean. Results were disap-
pointing, reportedly because a lack of si-
licic acid resulted in soft-shelled plankton
which were consumed by predators, rather
than dying off in large numbers and tak-
ing carbon with them as they sank to the
depths of the ocean floor.
In addition to fertilization using iron,
phosphate, and possibly nitrogen, another
possible method to create phytoplankton
blooms is to increase ocean upwelling to
pull nutrients from deep water up to the
surface. Like Keith's CO
2
removal machine,
this method was featured on Discovery
Channel's series “Planet Earth,” which showed
scientists crafting long plastic pumps op-
erated by wave action. The pumps proved
insufficient to withstand the ocean envi-
ronment, but this idea does offer a poten-
tial way to induce plankton blooms with-
out resorting to dumping materials into the
ocean.
A report on geoengineering from the
Royal Society in September 2009 concluded
that ocean fertilization, while potentially
cheap, offers only a relatively small capac-
ity to sequester carbon, while noting as well
that verifying the carbon sequestration
benefit is difficult. The report also cited
numerous potential undesirable side ef-
fects, including nutrient robbing, in which
essential ingredients besides the one be-
ing added are removed by the intervention
(for instance, nitrogen and phosphate are
removed when iron is added), thus depriv-
ing downcurrent communities of these in-
gredients. The report warned that all ocean
fertilization proposals involve intention-
ally changing the marine ecosystem and
stressed that the possible consequences
are uncertain.
other ways to go
Other greenhouse gas remediation ideas
include reforestation and sequestering
carbon dioxide in the form of charcoal,
otherwise known as biochar. As previously
mentioned, changes in land use account
for large amounts of greenhouse gas emis-
sions. In particular, deforestation is a ma-
jor cause of rising emissions. Forests are a
form of carbon sink, and the preservation
or planting of trees is particularly appeal-
ing as a carbon market commodity—yet
another way for countries and businesses
to meet their carbon reduction goals. Bio-
char is produced by taking the carbon diox-
ide removed from the atmosphere by plants
through photosynthesis and then captur-
ing the carbon by burning the organic ma-
terial in a low-oxygen environment to cre-
ate charcoal, which is then buried. Instead
of burying the biochar one can burn it, pro-
viding an alternative to fossil fuels. How-
ever, burying biochar reportedly improves
soil quality. The Royal Society report ques-
tions the efficiency of growing crops for
large-scale carbon sequestration and notes
