Ocean pumping of DOC

With a voice like Sean Connery, Professor Emeritus. Dr. Calvin of the UW School of Medicine (new book at http://williamcalvin.org )  talked about his ideas for how to mitigate rising CO2 levels.  His concerns arise in part from the 2-3x increase in the global drought index during the 20th century (Das et al., 2004; updated 2006).  He also noticed that around 1976 El Nino conditions began to predominate, though La Nina conditions were dominant beforehand.

In addition to more prevalent abrupt climate shifts, there were some near misses (like heart attacks?) since 1976:

  1. 1998 El Nino lasting longer
  2. 2005 Amazonia drought
  3. Antarctic flushing failure
  4. Labrador sea flushing failure

We need to sequester about 600 Gt of carbon over next 20 years to get back to pre-industrial levels.  Freeman Dyson’s favorite fix is doubling global forests, but climate conditions are getting worse for trees generally.  Photosynthesis already removes 210 GtC/yr, though it is mostly returned through respiration and decomposition.  This means we need new production that is sequestered for long time periods (probably best done in the voluminous oceans).

Much of the anthropogenic CO2 that has already been sunk is in the N Atlantic.  Major inputs are 2GtC/yr from deforestation and 8 from fossil fuels and cement.  92 are absorbed into ocean, and 90 are released.  In ocean 48 are photosynthesized, 37 are respired, and 11 settle through thermocline, and 0.01 are deposited on bottom.  So the big reservoir is dissolved organic carbon; it is 100x larger than the living biomass.

In the cold depths, about 1/2 of new DOC from upper ocean is soon converted into total CO2.  The rest has a 6kyr residence time (maybe because of multiple passes through surface system before removal).

Intervention A:  4x the settling rate (11 -> 44), but that would require a 4x increase in global productivity.

Intervention B: Pump down 30GtC/yr (600Gt over 20 years) maybe by fertilizing near downwelling zones (Greenland Sea whirl pools?) OR by mechanical pumping with wind or wave power.

Algaculture has advantage of controlling respiration.  Assume 50g of algae/m2/d about half of which is carbon.  Thus it takes 10-4 m2 (fingernail) to grow 1 gC/yr.  To sink 30Gt, you’d need 3×10^9 m2 or 3000 km2.

Field trials?  3,900 oil and gas platforms are in operation off coasts of Louisiana and Texas.  The north Sea presents a similar opportunity.

Indo-German iron experiment begins

At first glance this LOHAFEX experiment looks to be a step forward.  Understanding the longer-term evolution of carbon (and other) fluxes is a short-coming of past iron fertilization experiments.  This article suggests they will monitor the patch for about two months.

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Germany clears Indo-German Antarctic expedition

27 Jan 2009, 2307 hrs IST, Amit Bhattacharya, TNN

NEW DELHI: Ending days of suspense and anxiety for the Indo-German team of scientists sailing in the cold and desolate waters off Antarctica, the German government on Monday gave the go-ahead to a controversial ocean-seeding experiment that experts say could lead to a way of fighting climate change.

“This is the best Republic Day gift we could have hoped for,” S W A Naqwi, leader of the 29-member Indian scientific contingent aboard the ship, RV Polarstern, told TOI on email from the vessel. The expedition, called LOHAFEX, is now in the process of dropping 20 tonnes of iron sulphate across a 300-sq-km patch in the South Atlantic Ocean to study the resulting explosion of plant life that’s expected suck CO2 gas from the atmosphere and store it below the ocean.

The German government had put the expedition on hold, days after the scientists set sail from Cape Town on January 7, following protests from environmental groups. These groups said the experiment would breach an international moratorium on ocean iron fertilization (OIF) – as the technique is called – and could damage the marine ecology of the region.

“The last few days were full of anxiety. But we were confident that this would pass, and did not allow ourselves to be distracted from the task at hand. As a result, the suspension has not affected our work schedule at all. Right now, of course, everyone is excited and greatly pleased,” Prof Naqwi, who teaches at National Institute of Oceanography, said.

The “all-clear” came from the German ministry of education and research after the experiment was reviewed by three independent agencies – the British Antarctic Survey, Institute for Marine Research, Kiel, and the German Environmental Agency. “After a study of expert reports, I am convinced there are no scientific or legal objections against the… ocean research experiment LOHAFEX,” German research minister Annette Schavan said in a statement.

The scientists utilized the period of suspension to prepare for the experiment. “We have selected and surveyed a suitable ‘eddy’, a body of water that does not exchange much with the rest of the ocean. It’s located at 49S, 16W. After we got the green signal, we have filled the tanks with iron sulphate solution in seawater and began discharging this solution on Tuesday morning. The operation will take around 30 hours,” Naqwi said.

The iron seeding is expected to result in a rapid explosion of phytoplankton, an algae that quickly dies and sinks into the ocean along with the CO2 it absorbs during photosynthesis. “We will make regular observations inside and outside the fertilized patch, monitoring the evolution and demise of the algal bloom until early March,” Naqwi said.

OIF is seen as a promising geo-engineering method to trap billions of tonnes of CO2 below the ocean if conducted on a large scale.

LOHAFEX, the biggest and most comprehensive study of the method, is expected to provide vital answers about its efficacy and the effects it could have on marine ecology. With the method generating a lot of interest from private companies seeking to profit from it in the carbon trade market, a comprehensive scientific study will help policymakers frame appropriate laws on OIF.