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Fertilizing Oceans Seen Fruitless In Climate Fight
*Date:* /01-Feb-11/
*Country:* NORWAY
*Author:* Alister Doyle
Fertilizing the oceans to boost the growth of tiny plants that soak up
greenhouse gases is unlikely to work as a way to slow climate change, a
U.N.-backed study showed on Monday.
Such "geo-engineering" schemes would be hard to monitor and were likely
to store away only small amounts of carbon dioxide, the main greenhouse
gas, according to a report by the Intergovernmental Oceanographic
Commission.
"Geo-engineering schemes involving ocean fertilization to affect climate
have a low chance of success," according to the 20-page study by the
Commission, part of the U.N. Education, Scientific and Cultural
Organization (UNESCO).
The review, by scientists in seven countries, said 13 experiments in
recent years showed faded optimism that iron dust or other nutrients
could spur growth of microscopic marine plants and permanently suck
carbon dioxide from the atmosphere.
Twenty years ago, scientists had optimistically reckoned that one tonne
of iron could make the seas absorb 100,000 tonnes of carbon dioxide, it
said. But one recent study suggested that one tonne of iron would only
soak up 5,000 tonnes of the gas.
Firms including Climos, Atmocean Inc and the Ocean Nourishment Corp.
have been looking into ocean fertilization technology as a way of
offsetting emissions of greenhouse gases from factories, power plants
and cars.
MARINE SNOW
But the study said that some absorbed carbon simply returns to the
atmosphere. Just one to 15 percent falls as what scientists call "marine
snow" -- dead plants, animals or their faeces -- to be stored on the
deep ocean floor.
"At best it can make a small contribution" to storing industrial
emissions of carbon dioxide, Doug Wallace, lead author of the report at
the Leibniz-Institut fur Meereswissenschaften, told Reuters.
In 2008, the U.N.'s Convention on Biological Diversity imposed a
moratorium on ocean fertilization experiments outside coastal waters,
awaiting wider scientific evidence.
The study said that some experiments had successfully triggered a bloom
of plankton and bacteria -- such one in 2002 that produced a patch
visible to satellites in the north-east Pacific Ocean.
But it was impossible to say how much of that carbon stayed in the
oceans. And the extra plants might help fish grow in some areas by
providing more food, but might also rob nutrients from other parts of
the ocean.
Monitoring was vital, especially if ocean fertilization were ever to
qualify for carbon credits under a U.N. deal meant to avert more floods,
heatwaves, mudslides, or rising sea levels.
But it was far easier to monitor forests, which also soak up carbon as
they grow. "A tree might burn next year but then at least you know it
didn't work," Wallace said. "In the oceans you have a serious
measurement problem."
The study was also skeptical about measures to use huge pipes to suck
deep, nutrient-rich waters closer to the surface where sunlight could
spur more plant growth. And it did not even look at the possible costs
of marine geo-engineering.
© Thomson Reuters 2011 All rights reserved
<http://www.reuters.com/info/copyright>
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