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Geoengineering, including ocean carbon sequestration, is often promoted as a potential solution to climate change. But is ocean sequestration feasible? A review of the research indicates that all available techniques would either be expensive, ineffective, or both.
Growing Calls for Abatement of C02 Emissions
The United Nations Intergovernmental Panel on Climate Change (IPCC) estimates that between 1750 and 2011, humans emitted a total of 545 petagrams of carbon1 (PgC, or 109 metric tons), with current anthropo- genic emissions lev- els at about 8.5 to 13.1 PgC per year.2 Since the beginning of the industrial era, this rise has led to an increase in at- mospheric concen- tration from 278 to 390 parts per mil- lion.3
Significant temperature increas- es have been project- ed in both the near and long term, and global sea levels are projected to rise by 0.18 to 0.59 meters by the turn of the next century.4 Understandably, governments, multilateral organizations, and the private sector have become increasingly focused on ways to mitigate and reverse the destabilizing potential effects of climate change. Well-known policy pre- scriptions include mechanisms designed to limit emissions, such as carbon taxes, the Clean Development Mechanism (the UN's carbon offset program under the Kyoto Protocol), and market-based cap-and-trade arrangements, which have been implemented in jurisdictions from the European Union to California to Australia.
Such policies, designed to limit and eventually reduce C02 emissions, can be supplemented with "geoengineering" programs designed to actively sequester atmospheric carbon. The oceans, with their enormous volume, are seen as a potentially vast source of "storage" space for greenhouse gases.
The Promise of Geoengineering
"Geoengineering" refers to human manipulation of the environment on a global scale to avert climate change. The process takes advantage of "carbon sinks," or naturally occurring systems that trap and absorb large quantities of carbon otherwise present in the atmosphere.
Rain forests, farmed crops, algae, and other forms of plant life con- stantly breathe in C02, retaining it within their structures. Dead matter, de- tritus, and other forms of biomass (along with the carbon they contain) are then gradually incorporated (or "sequestered") into soil and water through a regular process of cyclical decay and growth.
Through land management techniques, afforestation programs (plant- ing trees in previously unforested areas), production of...