Plowing Under a Carbon-fixing Crop

The common criticism of ocean fertilization by upwelling nutrients from the depths is that it also brings up CO2 from the depths. If one does not explore the issue more fully, it makes one think that upwelling nutrients is counterproductive.

Things look different if one uses push-pump pumps rather than simply upwelling of nutrients. Some of you may recall this argument from my GLOBAL FEVER book from the Univ of Chicago Press, but the following is an excerpt from my more recent THE GREAT CO2 CLEANUP, chapter six:

To avoid competing with the world’s food production and supplies of fresh water, most sequestered carbon must come from new biomass grown in new places. Here I explore how paired ocean pumps might uplift nutrients and then sink the new organic carbon back into the ocean depths.

Instead of sinking only the debris that is heavy enough to settle out, as in iron fertilization, we would be using bulk flow to sink the entire organic carbon soup of the wind-mixed layer (organisms plus the hundred-fold larger amounts of dissolved organic carbon) before its carbon reverts to CO2 and equilibrates with the atmosphere.
        The CO2 later produced in the depths by the sunken carbon soup will reach the surface 400-6,000 years later. Smearing it out over that period greatly reduces the damaging peaks in ocean acidification and global fever.
...If we fertilize via pumping up and sink nearby via bulk flow (a push-pull pump), we are essentially burying a carbon-fixing crop, much as farmers plow under a nitrogen-fixing cover crop of legumes to fertilize the soil. Instead of sinking only the debris that is heavy enough, we would be sinking the entire organic carbon soup of the wind-mixed layer. 

        Algaculture minimizes respiration CO2 from higher up the food chain and so allows a preliminary estimate of the size of our undertaking. Suppose that a midrange 50 g (as dry weight) of algae can be grown each day under a square meter of sunlit surface, and that half is carbon. Thus it takes about 10-4 m2 to grow 1 gC each year. To produce our 30 GtC/yr drawdown would require 30 x 10¹¹ m² (0.8% of the ocean surface, about the size of the Caribbean).

        But because we pump the surface waters down, not dried algae, we would also be sinking the entire organic carbon soup of the wind-mixed surface layer: the carbon in living cells plus the hundred-fold larger amounts in the surface DOC. Thus the plankton plantations might require only 30 x 10⁹ m² (closer to the size of Lake Michigan). 

        The space requirement will be more because downpumps will not capture all of the new plankton; it might be less because the relevant algaculture focuses on oil-containing algal species and on harvesting a biofuel crop, not on plowing under the local species as quickly as possible. The ocean pipe spacing, and the volume pumped down, will depend on the outflow needed to optimize the organic carbon production. [The chemostat calculation FYI.] Only field trials are likely to provide a better estimate for the needed size of sink-on-the-spot plankton plantations, pump numbers, and project costs. Though ocean fertilization is usually proposed for low productivity regions where iron is the limiting nutrient, another strategy is to boost the shoulder seasons in regions of seasonally high ocean productivity. For example, ocean primary productivity northeast of Iceland drops to half by June as the nutrients upwelled by winter winds are depleted. Continuing production then depends on recycling nutrients within the wind-mixed layer. However, to the southwest of Iceland, productivity stays high all summer.

       Because not all of the new plankton will be successfully captured and sunk, fertilization will stimulate the marine food chain locally. Most major fisheries have declined in recent decades and, even where sustainable harvesting is practiced, it still results in fish biomass 73% below natural levels. At least for fish of harvestable size, there is niche space going unused.

       Locating the new plankton plantations over the outer continental shelves is more likely to supply a complete niche for many fish species, whereas deep-water plantations will lack variety. (The main commercial catch in deep water is tuna.) Also, down-pumping near the shelf edge would deposit the organic carbon in the bottom’s offshore “undertow” stream, carrying it over the cliff onto the Continental Slope into deeper ocean.

        Note that pumps would be tethered to the bottom so that the ocean currents are always creating a plume downstream: a plume of fertilizer near the surface and a second plume of carbon soup in the depths. (Pumping up from a different depth than pumping down will prevent the interaction that characterizes the oceanographers’ box models.) While the water might come back around in a thousand years, the plumes for the clean-up will only be about twenty years long and well diluted by that time.

Who Will Support Climate Repairs?

Avoiding catastrophe has not worked very well as a motivation for doing something about climate. Coleridge’s “suspension of disbelief” for stage performances seems to kick in for reality that sounds like a disaster movie. Nor has relying on the general environmental agenda been fast enough.

Mere reduction in the yearly fossil fuel emissions does not promise any reduction in heat waves or shoreline inundation or ocean acidification—only that they will get worse a little more slowly. The extreme weather of the last decade will only continue to prosper.

But climate repair, on top of the current preventative measures such as emissions reduction, promises much more than slightly slowing civilization’s disorganization and resource wars. Cleaning up the excess carbon dioxide in the air promises some real reversals in things that matter to many business and homeowner interests.

About 54 percent of the world’s population lives near an ocean shore, so let’s start with coastline interests. Ocean acidification is already affecting the shellfish industry, but sea level rise is the more widespread threat.

Fortunately, most current sea level rise is from the thermal expansion of the ocean’s surface layer—and that is mostly reversible as air temperature comes down.

A minor portion of the present sea level rise comes from ice sliding into the ocean from the shores of Greenland and Antarctica. Unfortunately, cooling may not stop it, given how melt water has already greased the skids at bedrock. If sea level rise is to be stopped, it is important to reverse thermal expansion so as to make room for any rise from ice sheet collapse.

Who’s interested in stopping sea level rise? Certainly the people of the eastern third of North Carolina, the southern half of Florida, and the southern half of Louisiana, all scheduled for inundation as overheating progresses.

But will people wait until regularly flooded before seeking action to reverse the ocean’s thermal expansion? No. Long before then, mortgages and shoreline slums will become the more immediate problem.

Guess what happens to the economy when lenders stop lending, for fear of never getting their money back? New construction will stop and many owners will no longer bother to maintain their threatened property. Instant slums.

The prospects of no new construction have already alarmed the real estate developers, judging from the science censorship attempt in the North Carolina legislature regarding sea level rise. 

Perhaps the bankers will also pressure governments to censor the scientists, just so depositors won’t be scared away by the uncertainty about getting their money back.

Even those still willing to lend will want the property to be insured. But insurers are not out to insure against major trends, such as rising sea level. The prospect of more superstorms also doesn’t fit their business model, what with high winds pushing water inland over a wide area in the manner of Hurricane Sandy.

As extreme weather intensifies, insurance companies will likely pull out of some regional markets, not merely raise their rates. That’s certainly what happened in Florida after four hurricanes hit in 2004-2005. And with no more insurance, no more mortgages. Their makeshift solution? Let the state taxpayers guarantee the insurance companies against major losses via big tax increases—just the thing to push the whole state into bankruptcy, if taxpayers start abandoning the place.

Civic booster groups are often out to polish their community’s image for those who might move into the area. Some will even whitewash local problems to help “maintain property values”—which leads us to an interesting question. 

How much of organized climate denial is a whitewash strategy in aid of keeping potential buyers ignorant for a little longer—while owners unload their property? Accustomed as we are to smokescreen efforts by the tobacco, asbestos, and petroleum industries, we often fail to spot the newer whitewash tactics of those with other aims.

Misleading propaganda only works with the poorly informed—it’s a sucker strategy, as in selling the Brooklyn Bridge. But it doesn’t work with the data-driven analysts who advise lenders and insurers. To counter the impression made by the ominous data trend requires a plausible scenario for reversing the climate prospects, such as a cleanup in progress.

Pushing hard for a quick climate repair that stops sea level rise is one thing that coastal and low-lying communities can do to save themselves. Taxpayers almost everywhere else will be having their own extreme weather and economic loss. It seems unlikely that they will pay to move all of Miami, New Orleans, and Galveston to higher ground.

Insurers already know from their own records that a 20 percent increase in peak wind speeds from 50 to 60 mph causes a 500 percent increase in windstorm claims. Guess what happens to insurance premiums?

In addition to more extreme windstorms, global overheating promotes deluge, both as rain and snow. It promotes drought and heat waves. Any one such episode can produce an instant slum—even a freeze-free winter that allows an insect infestation to quickly spread.

The obvious climate fix is to cool things off. But generating a high haze to reflect sunlight on a continuous basis, mimicking a long series of volcanic eruptions, is far too dangerous. The uneven coverage would tend to rearrange circulation patterns like the jet streams, triggering abrupt drought and flooding.

The only sustained way to cool things and reverse ocean acidification is climate repair—cleaning up the 43 percent excess of carbon dioxide in the air and then continuing it to counter any out-of-control emissions.

So who will support climate repair? Mayors and county executives, certainly, but potentially even the U.S. Chamber of Commerce, once new leadership takes over and they abandon their lobbying efforts promoting a climate whitewash. For the new leaders, climate repair will become the only game in town, essential to restoring confidence to buyers, lenders, and insurers.

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William H. Calvin is a professor emeritus at the University of Washington’s medical school in Seattle and the author of Global Fever: How to Treat Climate Change  (University of Chicago Press, 2008). The latest version of the CO2 cleanup was a finalist in MIT's 2013 geoengineering climate contest.

September 2014    WCalvin@UW.edu      faculty.washington.edu/wcalvin