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June 20, 2008 / Mridul

Afforestation Better Than Deep-Sea Carbon Storage

A large number of scientists have called for an immediate start of an global carbon storage program and many of them see the depths of North Sea as an appropriate place to initiate this one-of-a-kind solution to the ever rising carbon emissions. However there are voices of protests and disagreement notably from the Greenpeace. Greenpeace scientists argue that storing CO2 under the ocean floor would have adverse effects on the organisms living in the depths of the oceans. It is interesting to note that we are yet to discover a huge majority of deep sea species therefore endangering their habitat would certainly raise moral & ethical questions.

Dr Wallace S Broecker, a scientist at Columbia’s Lamont-Doherty Earth observatory argues for pilot projects for the evaluation of feasibility of deep sea carbon storage. He pointed out that carbon can be stored below 3,500 meters where it will change to liquid and will become denser than sea water. In a letter to Greenpeace scientist, Bill Hare, he said:

Experiments conducted by Peter Brewer, of the Monterey Bay Aquarium Research Institute, not only confirm that this is the case but also demonstrate that the CO2 injected rapidly reacts with sea water to form a solid clathrate, which is more dense than both liquid CO2 and sea water. Hence, the injected CO2 would end up on the sea floor as a slush. This would gradually dissolve, releasing the CO2 to the surrounding sea water, where it would react with the dissolved carbonate and borate ions to become chemically bound in the form of bicarbonate ion. As the concentration of carbonate and borate ions is small, the neutralization would take place gradually as the CO2-rich sea water mixed into the surroundings.

In response Dr. hare rightly points out our limited knowledge of the deep sea life processes.

The fact that deep water CO2 concentrations are currently lower than those of surface waters should not be taken as an indication of a vast unexploited capacity for CO2 disposal. Our knowledge of the biogeochemical processes which have contributed to the current distribution of CO2 in the deep oceans remains limited, as does our capacity therefore to predict the consequences of multi-billion tonne injections of CO2 at depth. To assume that uniformity of concentration is somehow an acceptable target, or one which will have minimal impact on marine ecosystems and the carbon cycle, is oversimplistic.

Although Dr Broecker explains the chemical transformations of stored carbon efficiently but his argument fails to consider the possible and largely unknown effects of such a large exercise (storing billions of tonnes of carbon dioxide). It would be wrong to assume that our actions won’t affect the deep sea organisms especially since we have negligible amount of knowledge & data regarding life in the deep seas. However, carefully monitored and independently reported pilot projects can certainly provide at least some answers but such projects must not be seen as a precursor to large-scale storage programs.

Oceans are one of the biggest sinks of carbon dioxide and store huge amounts of this greenhouse gas through natural processes but these processes are very slow – as compared to those found in case forests, another big carbon sink. Dr Broecker admits that even of the environment related concerns are addressed satisfactorily it would be the economic feasibility which would ultimately decide the fate of large-scale deep sea storage.

A UK based development agency, Yorkshire Forward, recently presented the conclusions of a study related to carbon storage in the North Sea. It said that such a project would take up to 20 years and cost £2 billion.

A better solution could be afforestation. Growing more trees, proper management and conservation of the fast depleting rain forests can, to a large extent, solve the problem of carbon storage. Cutting of rain forests, legally or illegally, must be stopped immediately. Logging rain forests for producing biofuels such as corn, maize and palm must be stopped.

As deforestation neared its record levels in Papua New Guinea threatening 80% reduction by the end of next decade, Indonesia signed an agreement with Papua New Guinea which would allow the Indonesian government to clear a definite area of rain forests for cultivation of palm trees.

Mandating polluting industries to maintain a green area around themselves would definitely help in the reduction of carbon dioxide. This would spare them from the multi-billion dollar carbon storage projects as the problem would be tackled locally.

Trees take up carbon dioxide at a much faster rate than than oceans, if the scientists are willing conduct pilot projects for deep sea carbon storage they must also consider studying the efficiency of ‘localized carbon removal’ by tree cover around polluting industries.


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