photo: Adam Hally via flickr.
Scratch one geoengineering scheme off the list of last-ditch ways for humanity to save itself: New research from the UK's National Oceanography Centre, Southampton shows that plans to pump nutrient-rich water up from the deep ocean in order the boost algae growth at the surface to absorb CO2 would likely only sequester a small amount of total anthropogenic carbon emissions, and if the system was stopped could lead to rapid release of greenhouse gases. Plan Would Mimic Natural Processes
In theory such a scheme would mimic the effects of natural ocean upwellings. The CO2 absorbed by the algae at the surface would be stored in the deep water as the algae sinks to the bottom.
In a way it's a similar thing to ocean iron fertilization, in the way it employs algae to store carbon, but this is more complex, employing "literally hundreds of millions of pipes" floating in the water.
This new study assumes that the logistical challenges of doing so could be overcome and examines the amount of carbon which could be sequestered and the risks involved.
Less Than One-Tenth Human Emissions Stored
The simulations done by Dr Andrew Yool and team show, using optimistic assumptions 3 gigatons of CO2/yr could be captured--less than 10% of total anthropogenic CO2 emissions.
The National Oceanographic Centre adds,
More significantly, when the simulated pumps were turned off, the atmospheric carbon dioxide levels and surface temperatures rose rapidly to levels even higher than in the control simulation without artificial pumps. This finding suggests that there would be extra environmental costs to the scheme should it ever have to be turned off for unanticipated reasons.
The results of the research have been published in Journal of Geophysical Research - Oceans
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