It has been proposed to "seed" the oceans with iron filings or other nutrients in an effort to stimulate the growth of phytoplankton (marine algae), and thus to remove CO2 from the atmosphere through photosynthesis. However, new research suggests this may not be an effective strategy, since less carbon is transported to the sea-floor during the summer months when algal growth is at a maximum than during the rest of the year.
The process is known as a "biological pump" because it incorporates CO2, in near-surface waters, into algae which then sinks into deeper waters and thus sequesters the carbon. As a corollary to this line of thought, the more algae there is in the surface regions the more CO2 is taken-up and the greater is the mass of carbon-rich detritus "pumped" to the bottom of the seas. The new findings, based on a novel mathematical analysis of the data, contravene this assumption, however.
The primary author of the paper, which is published in the Journal of Geological Research, Dr Michael Lutz, said: "The discovery is very surprising. If, during natural plankton blooms, less carbon actually sinks to deep water than during the rest of the year, then it suggests that the Biological Pump leaks. More material is recycled in shallow water and less sinks to depth, which makes sense if you consider how this ecosystem has evolved in a way to minimize loss. Ocean fertilization schemes, which resemble an artificial summer, may not remove as much CO2 from the atmosphere as has been suggested because they ignore natural processes revealed by this research."
Publication of the paper snaps close on the heels of a September Ocean Iron Fertilization symposium at the Woods Hole Oceanographic Institution (WHOI) at which were discussed matters related to environmental safety, economics and indeed just how effective the procedure might be in grabbing CO2, thus reducing its concentration in the atmosphere. Dr Hauke Kite-Powell, from the Marine Policy Centre at WHOI estimated a potential future ventures value of $100 billion for the technology on the international carbon trading market, and yet none of the major studies to date have demonstrated that it results in any significant degree of carbon sequestration. It is argued that these have been of too short duration and that vindication of the approach will need larger scale and more permanent experimental arrangements.
According to Professor Rosemary Rayfuse, an authority on international law and the law of the sea, based at the University of New South Wales, since such fertilization strategies are not approved under any carbon-credit schemes, the sale of "offsets" on the unregulated voluntary markets are "nothing short of fraudulent." She said: "There are too many scientific uncertainties relating both to the efficacy of ocean fertilization and its possible environmental side effects that need to be resolved before even larger experiments can be considered, let alone the process commercialized. Ocean fertilization is "dumping" which is essentially prohibited under the law of the sea. There is no pint trying to ameliorate the effects of climate change by destroying the oceans - the very cradle of life on earth. Simply doing more and bigger of that which has already been demonstrated to be ineffective and potentially more harmful than good is counter-intuitive at best."
Dr Lutz commented: "The limited duration of previous ocean fertilization experiments may not be why carbon sequestration wasn't found during those artificial blooms. Thuis apparent puzle could actually reflect how marine ecosystems naturally handle blooms and agrees with our findings. A bloom is like ringing the marine ecosystem dinner-bell. The microbial and food web dinner guests appear and consume most of the fresh algal food. Our study highlights the need to understand natural ecosystem processes, especially in a world where climate change is occurring so rapidly."
This is a fair point, and a timely reminder of the potential dangers of all strategies of "geoengineering". The earth is literally and mathematically a complex system, and it is a folly to try and compartmentalise its elements, "treating" aspects of them in isolation, when we don't really understand the nature of their interconnected whole. In "fixing" one "problem" we may trigger-off a whole host of sympathetic troubles by interfering in the natural balance of the planet-systems, and precipitating changes not predicted by any artificial algorithm of how the earth is supposed to behave, but may yet awaken us by rude reality.
"New research discredits $100B global warming "fix"," By Virgina Key. http://www.eurekalert.org/pub_releases/2007-11/uomr-nrd112907.php