Dumping tires in the water to create an artificial reef sounds either inspired or crazy.  It turned out to be crazy but there was a scientific hypothesis to it.  You just had to buy into their chain of logic.

There was also a lesson.   Not everything needs to be done in a large experimental setting but the justification to go ahead and do it is always cost and the protecting the environment right now.   'You care about the environment, right?'   I can't think of a single time a question has been phrased that way that someone hasn't tried to sell me something.  And the cost savings are always framed to be immediately practical, though in the case of the artificial reef made of tires, the cost to clean up was 5000 times as much as it was supposed to save.

That's just an example, of course, one failed experiment does not mean all experiments are failures but it does mean we should learn from mistakes so as to make fewer failures.

A few weeks ago I wrote about the LOHAFEX experiment to dump iron sulphate in the Southern Ocean, the hypothesis being that iron fertilization on a mass scale would drag a lot of CO2 to the bottom of the ocean.    Like with building an artifical reef, the tires were not the concern, landfill space was - incorrectly, it turned out.   Like those tires, iron fertilization is one of the few areas where environmental activists, practically all scientists except the ones who want to do it (and in the case of iron fertilization, have already done five similar experiments in the Southern Ocean without creating convincing data) and 191 UN countries all agree it is a bad idea.    Why?  Because the ecosystem is complex and if it turns out we are warming because of more than just CO2, the cost to fix a bunch of garbage in the ocean could be 5000 times what we think we are saving.   Since I wrote about it, the mainstream media has also caught on and a new Nature article casts even more doubt on its viability.

 But LOHAFEX is not alone.   It seems throwing garbage in the ocean is something other people want to do as well.  Stuart Strand, a University of Washington research professor in College of Forest Resources, is an environmental engineer who has done a lot of work fixing contaminated soil and water using plants.   Along with Gregory Benford, a professor of physics at the University of California, Irvine, Strand wrote a paper suggesting that putting bales of 'global crop residues' in the ocean could be a way to combat global warming.

Poor oceans - they can't get a break.    Some people will object to my use of the term 'garbage' but unless you keep corn stalks stored in your house, that's really what we are talking about.   

In principle, doing something counterintuitive that ends up doing something terrific is part of the beauty of science exploration so I am not fundamentally against dumping things in the ocean but it has to make scientific sense to a lot of people, not just a few, so let's examine  what they are talking about.

Strand and Benford say their proposal is better than, coincidentally, iron fertilization for taking carbon out of the atmosphere because, if their numbers are correct, the carbon released during the harvest, transportation and sinking of 30 percent of U.S. crop residues compared to the carbon that could be sequestered makes their proposes process 92 percent efficient, much more efficient than leaving crop residue in the field (14% efficient at sequestering carbon) or making ethanol (32% efficient) but mitigates some use of fossil fuels.  We have to leave that alone for a moment because they're just numbers - no one would ever get any press going from 14% efficiency to 15% so the numbers are going to be bold but they clearly believe them.

And they certainly seem to be tackling the correct problem (landfills rather than tires, staying in our example above) - there are billions more people on the planet than when I was born and all of those people require food and optimized farming techniques, which produce CO2 and methane and lots of  pollutants.    CO2 mitigation is the source of some controversy because of the economic and political genesis of efforts to highlight that part of the data but there can't be much denial we are warmer - if we're not warmer with all those extra people, we have a big hole in the sky letting out heat and that can be a problem all its own.

Using their figures, 30% of the world's crop residue represents 600 megatons of carbon.  If sequestering in the deep ocean is really 92 percent efficiency, that would mean the amount of carbon dioxide in the atmosphere would be reduced from 4,000 megatons of carbon to 3,400 megatons annually - a 15 percent decrease.  

Why not use 100% of the crop residue then?   Global warming = solved, right?    You need some biomass residue to maintain carbon in the soil and if we start using a lot of fossil fuels to ship these bales of garbage from deep inland to the ocean, it makes a lot less climate sense, sort of like believing CFL bulbs with mercury in them manufactured and shipped from China to the US are actually helping the environment.

Their hypothesis is that we would drop these bales of stalks and leavins' onto alluvial fans found off the continental shelf, where rivers pour into the ocean. Alluvial fans form as silt and debris from river water settles to the seafloor so bales deposited there would be covered with silt, sequestering the carbon.

biomass crop residue carbon sequestration
The continental shelf in the Gulf of Mexico, marked with the blue line, is a proposed idea of where the biomass garbage could be dumped.   A 'fan' of sediment has formed on the seafloor made up of silt and debris that settles out of Mississippi River waters flowing into the gulf and residues sunk in such fans would become covered with silt, so their belief is the carbon would be locked away for long periods.  Credit: S. Strand/UW/U.S. Geological Survey

What about the environmental impact?   Well, we don't know.   The ocean is a mighty and awesome beast and it would be great to think little old humanity can't do a lot of harm.  The researchers say acidification and other effects of global warming will be worse than anything these bales of  crop residue do.   No one, including them, is naive enough to believe this would have no impact.

They say any method for removing excess carbon dioxide must do 7 things:

(1) Move enough carbon to have an impact
(2) Do it in an efficient way
(4) Sequester that carbon for thousands of years
(4) Be repeatable indefinitely
(5) Be something that can be implemented now and not wait for some scientific magic bullet
(6) Only cause a moderate amount of environmental damage.
(7) Be economical. 

Their belief is that this method of sequestering can accomplish that.

One thing everyone in science agrees on is that going carbon negative would be a good thing.    It is unlikely that a bureaucratic solution with a politically suspect origin like setting arbitrary dates for CO2 targets will ever be implemented by the largest countries.  Sequestering biomass, and therefore carbon, into the ocean is not a perfect solution but they say limiting it to a small area (260 square kilometers, about 0.02 percent of the area of the Gulf of Mexico, they say) would accomplish the necessary effect.

Unlike iron fertilization, which has had 15 years of experimentation and enough data that 191 countries are against it, this is basically untested.   

So what do you think?   Can Ma Nature take our excess biomass and the carbon stored within without issue?

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Article: Stuart E. Strand,Gregory Benford, 'Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments', Environmental Science&Technology January 12,2009 Article ASAP