Unrestricted ocean fertilization may invite disaster, says MIT environmental expert.
A policy tool for curbing global warming could potentially
wreak havoc on the oceans if instituted with no restrictions,
warns an MIT professor in the October 12 issue of Science.
Carbon trading, an innovative feature of the Kyoto
Protocol on climate change, provides a mechanism for
countries to meet reduced emission targets. Under the
proposed policy, a country that exceeds its limit in
emissions of the principal greenhouse gas, carbon dioxide,
could fulfill its commitment by purchasing “carbon
credits” from a country that emits less than its
Carbon credits could also be purchased from companies
that develop ways to remove carbon from the atmosphere.
And therein lies the hitch, says Sallie Chisholm, MIT
professor of biology and civil and environmental engineering.
Fertilizing the High Seas
One potential technique for removing atmospheric carbon
involves fertilizing the oceans. As pilot experiments
over the last ten years have shown, fertilization can
increase the number of tiny organisms, or phytoplankton,
that remove carbon dioxide from the atmosphere as part
of their normal growth. Some of those organisms fall
to the bottom of the sea or are eaten and fall to the
bottom as fecal matter, essentially moving carbon out
of the air and into the deep.
Entrepreneurs watching these developments have concluded
that fertilizing large patches of ocean might therefore
be profitable if carbon trading is instituted.
“Proponents claim that ocean fertilization is
an easily controlled, verifiable process that mimics
nature; and that it is an environmentally benign, long-term
solution to atmospheric CO2 accumulation,” write
Chisholm and co-authors Paul G. Falkowski of Rutgers
University and John J. Cullen of Dalhousie University
“These claims are, quite simply, not true.”
Ocean fertilization is not easily controlled, say the
researchers. “A fertilized patch in turbulent ocean
currents is not like a plot of land. The oceans are
a fluid medium, beyond our control.”
How Green Is It?
Chisholm is particularly critical of claims that ocean
fertilization is environmentally benign. “What
really surprises me is that they’re ignoring the results
of years of research on aquatic ecosystems,” including
the negative effects of nutrient enrichment in lakes
and coastal waters.
Many studies have shown that over-stimulated plant
growth can lead to oxygen depletion and the elimination
of species vital to the food web. If oceanic food webs
were to be significantly altered, the results “could
be very damaging to the global oceans.”
Chisholm emphasizes that she’s not against individual
experiments in which ocean fertilization is used as
a tool for studying the ocean’s response to enrichment.
Such experiments have already yielded “very exciting
results that have contributed to our understanding of
the role of the oceans in the global carbon cycle and
in regulating climate.”
But “we are against the large-scale implementation
of ocean fertilization as a carbon sequestration option,”
Closing the Door
Commercial implementation of ocean fertilization techniques
is not imminent, but interest is growing. About seven
patents have been filed on different techniques, and
at least three small companies have been established.
Chisholm herself recently talked to a representative
from Mitsubishi Heavy Industries. “So many large
companies are watching with interest,” she says.
Although Chisholm notes that fertilizing a relatively
small patch of water would not by itself change the
ecology of the oceans, she fears a potential slippery
slope. “If it’s profitable for one, it would be
profitable for many, leading to exploitation and a classic
tragedy of the commons,” she says.
“One simple way to avert this potential tragedy
is to remove the profit incentive for manipulation of
the ocean common,” she writes in Science.“We
suggest that ocean fertilization in the open seas, or
territorial waters, should never become eligible for
Author: Elizabeth Thomson
News Service: Technology Review