Geoengineering efforts to bring oxygen into the deep Baltic should be abandoned, says Daniel J. Conley.
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Conley, D. Save the Baltic Sea. Nature 486, 463–464 (2012). https://doi.org/10.1038/486463a
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DOI: https://doi.org/10.1038/486463a
peggy hopper
Phosphorus pollution of the Baltic wastes an increasingly valuable resource. Only five countries control 90% of the world's mined phosphate which makes the supply vulnerable to political or monopolistic manipulation. The price, which had been steady for decades, was subject to a more than tenfold hike in 2008 and is now 50% of the peak. Phosphorus is vital to agriculture; formerly the substitute for mined rock was collecting bones from slaughterhouses. Sci.Am.2008
Dr. Conley could have included the scarcity and possible price increase of phosphorus in his argument favoring conservation instead of geoengineering. Sewage treatment plants produce a salable fertilizer besides preventing pollution.
E Kite
Does the author have any competing financial interests, or financial interests that a reasonable person might perceive as competing?
Ffion Cleverley
Posted on behalf of Drs. O. Magnus Karlsson, J. Mikael Malmaeus and Christian Baresel
Efforts to bring oxygen into the deep Baltic to increase precipitation of phosphorus should be abandoned, advocates Daniel Conley. His opinion is based on estimates of costs for establishing oxygenation pumps and speculations about ecological damage this could create. Instead, he suggests that mitigation measures focus entirely on reducing nutrient loads.
Conley gives examples of grants to projects testing different engineering methods. Those figures are irrelevant to determine cost efficiency of, e.g., oxygenation. What matters is how much phosphorus that is removed per money unit spent. This can be achieved only through a proper cost-benefit analysis, which has not yet been possible to do because the technique for oxygenation is still under development. However, such analyses have been done for nutrient load reductions. What we do know is that actions Conley calls for, e.g., massive nitrogen reduction from farming areas (D.J. Conley et al. Science 323, 1014-1015; 2009, besides from being uncertain regarding its efficiency (D.W. Schindler & R.E. Hecky Science 324, 721-722 2009) are associated with yearly costs within the range of billions of ?, if implemented.
The ecological risks Conley refers to must be taken seriously before applying geoengineering. Nature itself has provided us with possibilities of testing oxygenation. Several Baltic coastal areas near municipalities have historically been polluted from both toxic and eutrophicating substances. Some of these areas are now recovering (O.M. Karlsson et al. AMBIO 39, 486-495; 2010) but there are not any reports of high levels of harmful substances or adverse effects on biota due to dead bottoms being recolonized.
Any method to reduce the trophic level of the Baltic Sea has its ups and downs. Effluent treatment requires energy and produces carbon dioxide emissions. Actions on farming areas will lead to large-scale changes of the landscape. Society decides which remedy of land based sources and historical deposits we finally undertake. Whether oxygenation is a cost-effective method against eutrophication must be tested before any scientifically based advice can be given.