 | |  |
|
| Enlarge ImageThe brilliant swirls of green and blue in the midst of the deep, blue Atlantic Ocean off Argentina were created by multitudes of tiny marine plants (phytoplankton) that draw carbon dioxide from the atmosphere to grow. Intentionally adding iron to the ocean would fertilize more phytoplankton blooms. Could this help reduce the buildup of greenhouse gases? (Image courtesy of NASA) |
|
|  |
|
| Enlarge ImageA plume of dust from Alaskan glacial sediments blows far into the Pacific Ocean. Storms like this, or from vast deserts such as the Sahara, are the natural way that iron gets into oceans to fertilize phytoplankton blooms. (NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team, Goddard Space Flight Center) |
|
|  |
|
| Enlarge ImageIron fertilization experiments can set off blooms that are visible from space. In the bottom center of the satellite image above, note the red patch (indicating high levels of chlorophyll) from the Subarctic Ecosystem Response to Iron Enrichment Study in 2002. (Image provided by Jim Gower, Bill Crawford, and Frank Whitney, Institute of Ocean Sciences, Sidney BC.) |
|
|  |
|
| Enlarge ImageScientists aboard the Australian research vessel Aurora Australis studied the natural cycling of iron in the Southern Ocean in 2001. Ken Buesseler, a marine chemist at Woods Hole Oceanographic Institution, was aboard that expedition, and in 2002 he served as chief scientist of the Southern Ocean Iron Experiment (SOFeX). The three-ship operation added iron to stimulate a phytoplankton bloom in the Southern Ocean and investigated the results. (Photo by Ken Buesseler, Woods Hole Oceanographic Institution) |
|
|  |
|
| Enlarge ImageTwelve small experiments over the last decade in several ocean locations (red dots) consistently showed that intentionally adding iron results in phytoplankton blooms. (Data courtesy of NASA SeaWiFS Project.) |
|
|  |
|
| Enlarge ImagePhytoplankton blooms draw down carbon dioxide from the atmosphere. They are eaten by zookplankton, which produce pellets and aggregates of carbon-containing fecal matter (above), which sink into the depths, where the carbon can be sequestered from the atmosphere. How much carbon would actually be sequestered via ocean iron fertilization is an open question. |
|
|  |
|
| Enlarge ImageUnderlying proposals to add iron to the ocean as a means to mitigate climate change is the brutal fact that atmospheric carbon dioxide levels have increased precipitously since the 1850s and continue to rise. CO2 levels for the past 1,000 years were derived from ice cores. The inset shows direct atmospheric CO2 observations from Mauna Loa, Hawaii, beginning in 1958. (Adapted from Sarmiento & Gruber. Inset: from C.D. Keeling and the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory) |
|
|  |
|
| Enlarge ImageDebating the pros and cons of ocean iron fertilization at a panel at the WHOI conference are (left to right): Elizabeth Kim of the U.S. Environmental Protection Agency; Lisa Speer of the National Resources Defense Council; and Margaret Leinen of Climos Inc. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution) |
|
|  |
|
| The Ocean Iron Fertilization conference, which drew a variety of stakeholders in the debate, was organized by (left to right) WHOI marine chemist Ken Buesseler, Hauke Kite-Powell, a researcher at the WHOI Marine Policy Center, and WHOI marine chemist Scott Doney. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution) |
|
|
Related Multimedia |
|
How Carbon Cycles Through the Earth
Illustration by Jack Cook, Flash by Katherine Joyce, Woods Hole Oceanographic Institution | » View Flash
|
|
|
|
|
Related Files |
|
|
|
|
|
Related Links |
|
|
(First article in a six-part series)
Part 2: Will Ocean Iron Fertilization Work?
Part 3: What Are the Possible Side Effects?
Part 4: Lessons from Nature, Models, and the Past
Part 5: Dumping Iron and Trading Carbon
Part 6: Proposals Emerge to Transfer Excess Carbon into the Ocean
“Give me half a tanker of iron, and I’ll give you an ice age” may rank
as the catchiest line ever uttered by a biogeochemist. The man
responsible was the late John Martin, former director of the Moss
Landing Marine Laboratory, who discovered that sprinkling iron dust in
the right ocean waters could trigger plankton blooms the size of a
small city. In turn, the billions of cells produced might absorb enough
heat-trapping carbon dioxide to cool the Earth’s warming atmosphere.
Never mind that Martin was only half serious when he made the remark
(in his “best Dr. Strangelove accent,” he later recalled) at an
informal seminar at Woods Hole Oceanographic Institution (WHOI) in
1988. With global warming already a looming problem, others were
inclined to take him seriously.
At the time, ice-core records suggested that during past glacial periods, natural
iron fertilization had repeatedly drawn as much as 60 billion tons of
carbon out of the atmosphere. Laboratory experiments suggested that
every ton of iron added to the ocean could remove 30,000 to 110,000
tons of carbon from the air. Early climate models hinted that
intentional iron fertilization across the entire Southern Ocean could
erase 1 to 2 billion tons of carbon emissions each year—10 to 25
percent of the world’s annual total.
Since 1993, 12 small-scale ocean experiments have shown that iron
additions do indeed draw carbon into the ocean—though perhaps less
efficiently or permanently than first thought. Scientists at the time
agreed that disturbing the bottom rung of the marine food chain carried
risks.
Twenty years on, Martin’s line is still viewed alternately as a boast
or a quip; an opportunity too good to pass up or a misguided remedy
doomed to backfire. Yet over the same period, unrelenting increases in
carbon emissions and mounting evidence of climate change have taken the
debate beyond academic circles and into the free market.
Today, policymakers, investors, economists, environmentalists, and
lawyers are taking notice of the idea. A handful of companies are
planning a new round of larger experiments. The absence of clear
regulations for either conducting experiments at sea or trading the
results in “carbon offset” markets complicates the picture. But
economists conclude that the planet’s growing urgency to solve its
emissions problem will reward anyone who can make iron fertilization
work.
In past experiments “we were trying to answer the question, ‘how does
the world work?’—not ‘how do we make the world work for us?’ ” Kenneth
Coale, the present-day director of Moss Landing Marine Lab, said
recently. “They’re totally separate. We have not done the experiment to
address the issues that we’re talking about today.”
“We’re in a learning process that involves a balance of science,
commercial, and a whole variety of social activities and interests,”
Anthony Michaels, director of the Wrigley Institute for Environmental
Studies at the University of Southern California, said. “We’ve got to
set up a measured process for moving forward.”
The two scientists were speaking at a fall 2007 conference that brought
together some 80 participants representing the scientific, commercial,
regulatory, and economic sides of the debate. The conference was
convened by WHOI marine geochemists Ken Buesseler and Scott Doney, and
Hauke Kite-Powell of the WHOI Marine Policy Center. In talks and
wide-ranging discussions, participants raised serious doubts about the
practicality, efficacy, and safety of large-scale iron fertilization.
Yet many also seemed to accept that more science—in the form of
carefully designed and conducted experiments—was the best way to put
those doubts to rest.
Not as simple as it sounds
Martin made his pronouncement jokingly because he knew that he was
glossing over several hindrances to using iron fertilization to
sequester carbon in the ocean. Opponents to the idea are quick to point out the three major ones: It may be less efficient
than it at first seems; it raises a host of new, worrying consequences;
and its effectiveness is difficult for anyone to measure.
In certain regions, including the equatorial and north Pacific and
the entire Southern Ocean, a simple iron addition does cause
phytoplankton to grow rapidly. But tiny zooplankton, known as
“grazers,” eat much of the bloom almost as soon as it starts. This
begins a chain of recycling that ensues from the sea surface to the
seafloor as grazers, krill, fish, whales, and decomposers feed upon
each other. Much of the immense carbon prize won by the iron addition
quickly leaks back into the atmosphere as carbon dioxide gas.
What is critical for the effectiveness of iron fertilization schemes is
the amount of organic carbon that actually sinks from the surface and
is sequestered in the depths. Only a small percentage of carbon—in the
form of dead cells and fecal pellets—falls to the seafloor and
stays there, unused, for millennia. A higher percentage (between 20 and
50 percent) will at least reach middle-depth waters, where the carbon
will remain in underwater currents for decades. Proponents consider
this result good enough to buy society time to come up with other, more
permanent solutions to greenhouse gas increases.
Beyond the inefficiency of carbon sequestration, iron fertilization
would likely cause other changes “downstream” of the ocean patches
where iron was added. The huge green phytoplankton blooms would take up
not just iron but other nutrients, too—nitrate, phosphate, and
silica—essentially depleting nearby waters of the building blocks
needed for plankton growth.
“You might make some of the ocean greener by iron enrichment, but
you’re going to make a lot of the ocean bluer,” said Robert Anderson,
senior scholar at Lamont-Doherty Earth Observatory.
Other participants at the WHOI conference—John
Cullen, a biological oceanographer at Dalhousie University in Canada, Andrew Watson, a biogeochemist at the University of East
Anglia, U.K., and Jorge Sarmiento, a modeler at Princeton’s Geophysical
Fluid Dynamics Laboratory—pointed out several other ecological
concerns. Large-scale iron fertilization, in altering the base of the
food chain, might lead to undesirable changes in fish stocks and whale
populations. Increased decomposition of sinking organic matter could
deprive deep waters of oxygen or produce other greenhouse gases more
potent than carbon dioxide, such as nitrous oxide and methane. The
plankton-choked surface waters could block sunlight needed by deeper
corals, or warm the surface layer and change circulation patterns.
On the other hand, more plankton might produce more of a chemical
called dimethylsulfide, which can drift into the atmosphere and
encourage cloud formation, thus cooling the atmosphere and helping to
counteract greenhouse warming. And others argue that increased plankton
supplies might enhance fish stocks.
Then there is the practical problem of verification. Iron fertilization
companies would earn profits by measuring how much carbon they
sequester and then selling the equivalent to companies (or people) that
either wish to or are required to offset their emissions. Any plan to
sell sequestered carbon requires a reliable accounting, and this
promises to be difficult in the ocean.
So far, only three of 12 iron addition experiments have been able to
show conclusively that any sequestration happened at all, according to
Philip Boyd of the New Zealand National Institute of Water and
Atmospheric Research. Perhaps more worrying to an investor, those
sequestration numbers were low—about 1,000 tons of carbon per ton of
iron added, as opposed to the 30,000 to 110,000 suggested by laboratory
experiments.
Carefully designed research
Despite the suspected drawbacks to full-scale iron fertilization,
private companies—and many scientists—support the idea of another round
of experiments. Learning more about the ocean is in everyone’s
interest, they argue, and the larger experiments now being proposed are
still far too small to wreak environmental havoc.
While the past experiments showed widely variable results, proponents
read this as an opportunity for refinement through engineering. For
millennia, humans have been repeating processes that at first were
marginally useful and tuning them to our purposes. Continued research
could address a number of key questions (see box below), and those answers
could point the way to higher yields and efficiency.
Proponents of iron addition do acknowledge the possibility of
environmental ill-effects. Still, no such effects have been detected
during the past 12 experiments, probably because the experiments were
small—around a ton of iron added over a few hundred square kilometers
of ocean. By incrementally scaling up, they believe they can detect and
avoid environmental problems.
As for the verification problem, both carbon markets and international
ocean law are moving to accommodate so-called “carbon sink” projects,
such as iron fertilization, which capture and sequester carbon from the
air, according to Till Neeff of EcoSecurities, a leading trader of
carbon credits, based in London. By the time the science is worked out,
he said, the economics may be worked out as well.
Anchoring all of the arguments for continued research is the brutal
fact of global carbon emissions. The most practical hope for dealing
with emissions at the moment lies in a piecemeal strategy of
“stabilization wedges.” Under this proposal, the world develops a
portfolio of emissions reductions and carbon-capture projects, each of
which offsets one piece of the global emissions pie. Combined, these
wedges must begin to slow the growth of, and eventually lead to a net
reduction in, our current global emissions of 7 to 8 billion tons of
carbon per year. But with minimal progress so far on any wedges, and
with China and India committing to major emissions increases as they
develop, iron fertilization beckons as one tool in a toolbox of partial solutions.
“No option is without its impacts,” said WHOI biogeochemist Ken
Buesseler, “whether we use wind turbines, grow biofuels or use
energy-saving fluorescent bulbs, which contain mercury.”
But is it legal?
At present, iron fertilization falls into a gray area in both
international law and formal carbon-trading markets, but this is
changing.
Iron fertilization would happen on the open ocean, which is not owned
by any country, according to David Freestone, senior adviser in the
Legal Office of the World Bank, who briefed
the symposium participants. While international treaties such as the
London Convention, which governs ocean dumping and pollution, might
address iron addition, treaty nations have not yet decided whether it
might constitute pollution because its possible side effects remain
unknown. Further, no overarching international agency exists to
enforce the treaty, so responsibility falls to individual nations, he
said. Ship crews intending to flout an international treaty could do so by
electing to fly the flag of a country that has not signed it—a route that has
already been publicly considered by one company.
Carbon trading markets are young but growing, Neeff said. Strictly
regulated markets, set in motion by the Kyoto Protocol treaty, last
year traded 430 million tons of carbon offsets (worth billions of
dollars) among companies required to reduce total emissions. (One ton
of carbon equals 3.67 tons of carbon dioxide.) Regulatory markets don’t
allow for iron fertilization at present, but this may change as more
carbon sink projects gain approval.
Then there are voluntary markets, Neeff said, where concerned
individuals or companies buy carbon offsets to assuage their conscience
or green their image. Traders would be free to sell offsets from iron
fertilization in these markets. Voluntary markets are growing rapidly,
Neeff said, but so far they are much smaller than regulatory markets,
equivalent to 7 million tons of carbon, worth about $400 million, per
year.
Voluntary markets represent one more worry for opponents of iron
fertilization. Iron fertilization companies
might make superficial estimates of the amount of carbon they sequester
and enter a hefty balance in their trading ledgers. Any large profits
made from under-regulated credits would encourage other outfits to go
into business. The collective impacts to the world’s international
waters could be both disastrous and impossible to trace to any single
liable party, Cullen said.
But those are future scenarios. By the time iron fertilization moves
from experiment to industry, laws may well be in place to regulate it,
said Kite-Powell. Over the same period, increasing demand for carbon
offsets is likely to ensure that iron fertilization is profitable, he
said, referring to a recent economic analysis indicating a potential
value of $100 billion over the next century.
Next steps: scientists and industry
Iron fertilization is being pulled in two directions, as comments during a panel discussion at the conference made clear.
Iron fertilization is not a silver bullet, said Margaret Leinen, the
chief science officer at the firm Climos and former assistant director
of geosciences at the National Science Foundation. But given the
enormity of the greenhouse gas problem and the lack of progress so far,
“let’s look at it in our portfolio for mitigation,” she said.
“Uncertainty about the impacts shouldn’t preclude careful research.”
Lisa Speer of the Natural Resources Defense Council took a different
view: “There is a limited amount of money, of time, that we have to
deal with this problem,” she said. “The worst possible thing we could
do for climate change technologies would be to invest in something that
doesn’t work and that has big impacts that we don’t anticipate.”
Between these viewpoints a middle ground emerged: “There are plenty of
ways to do it wrong, but done right, [iron fertilization] does actually
sequester carbon for hundreds of years in the place that it would
ultimately end up anyway,” Watson said. That may be a tremendous
advantage compared with more familiar but less secure approaches like
planting trees, he said. Skeptics should not dismiss the idea out of
hand before scientists have had the chance to work out the details.
One way to quell doubts lies with carefully conducting larger
experiments. But iron fertilization is unlikely to receive much more
federal funding. It falls to entrepreneurs concerned about the climate
problem to fund the work, and they need scientists’ participation to
make sure the right questions are asked and answered.
In a parallel with the way universities routinely conduct trials of the
safety and efficacy of potential pharmaceuticals, Michaels pointed out
that oceanographers may need to learn how to be involved with tests of
iron fertilization. “We have to evolve a set of skills within our
community to have those kinds of roles,” he said. “Who else should be
figuring that out but us?”
Though many scientists are keen on the idea of future research, fewer
are willing to team up with a private company to do it, for fear of a
real or perceived effect on the impartiality of their research. Still,
researchers may need to convince themselves that just because the idea
is potentially profitable doesn’t mean it’s wrong—or simply accept that
further research is going to happen.
“Commercial efforts are moving forward with or without scientific
input,” Buesseler said. “We need to be able to evaluate their impacts
and changes to the ocean carbon cycle, based upon the best possible
oceanographic methods.”
For their part, private companies hope to collaborate with researchers.
Of the handful already in business, one—Climos—recently proposed a code
of ethics supporting involvement by scientists and full environmental
audits of experiment plans. Russ George, president of rival company
Planktos, who also attended the conference, agreed in principle to the
code. On Nov. 5, Planktos announced that it had dispatched a ship
equipped for an iron fertilization experiment but made no statements
about how it might comply with the code.
What’s emerging for the next few years is the prospect of a round of
experiments involving around 100 tons of iron, which is 100 times
larger than previously tried. Financed by private companies, they could
either be conducted by private interests with limited sampling gear or
by teams of scientists through grants. New, autonomous technology
promises to extend the duration of monitoring and improve measurements
of how carbon sinks through the ocean.
Yields from previous experiments cannot be used to project whether
larger-scale fertilizations would send millions, thousands, or even
fewer tons of carbon into the ocean’s middle depths, Buesseler said.
Still, commercial groups sponsoring new experiments hope to sell those
carbon dioxide equivalents as voluntary offsets. While scientific
research would focus on learning more about how the ocean works, the
companies involved would be looking for ways to increase efficiency,
make larger blooms in the future, and monitor any negative effects. As
government-sponsored research on iron fertilization moves ahead in
different countries, funding for larger experiments could develop into
private and public partnerships.
Experiments on such a scale drive home one final point: that the near
future of iron fertilization is modest on all counts—size of
experiments, likely profits, environmental side-effects, and amount of
carbon sequestration. However profitable iron fertilization becomes,
the dent it puts in atmospheric carbon levels in coming years will
remain a small one. As these ocean scientists work to assemble their
stabilization wedge to mitigate carbon dioxide emissions, they remind
the rest of the world that many more wedges must be found.
—Hugh Powell
The
Ocean Iron Fertilization Symposium: Some 80 natural and social
scientists from several countries—along with environmental advocates,
business representatives, policymakers, legal experts, economists, and
journalists—gathered at Woods Hole Oceanographic Institution (WHOI) on
Sept. 26-27, 2007, to discuss the pros and cons of ocean iron
fertilization as a means to mediate global warming. This series of Oceanus
articles summarize the wide range of issues raised at the conference,
convened by WHOI scientists Ken Buesseler, Scott Doney, and Hauke
Kite-Powell. They reviewed and edited these articles, with input from
many conference participants. All the articles in this series will be
published next week in a print edition of Oceanus (Vol.
46, No. 1). Videos and PDF versions of presentations at the conference
are available at http://www.whoi.edu/conference/OceanIronFertilization.
The symposium was sponsored by the Elisabeth and Henry Morss Jr.
Colloquia Fund, the Cooperative Institute for Climate Research at WHOI,
the WHOI Marine Policy Center, the WHOI Ocean and Climate Change
Institute, the WHOI Ocean Life Institute, and Woods Hole Sea Grant.
Unresolved QuestionsTwelve small experiments have shown that blooms of phytoplankton consistently result from intentional addition of iron to the ocean. But the efficacy and ecological impacts of iron fertilization remain uncertain, particularly with larger-scale experiments. If and when a new round of experiments is begun, these questions will be first on the list:
- How long will carbon be sequestered in the ocean?
- How deep is deep enough to accomplish this?
- How can sequestration efficiency be increased?
- How does the ocean food web change during and after a bloom?
- Which phytoplankton and grazers raise sequestration efficiency?
- Which parts of the ocean are best for iron fertilization?
- What size and what shaped patch should be fertilized?
- How often and how continually should iron be added?
- What kinds of currents and surface conditions give the best results?
- How can the amount and fate of carbon from a bloom be verified?
- How could effects downstream of experiments be detected?
- How could the production of other greenhouse gases be monitored?
|
Posted: November 13, 2007 [top] |
