I can haz carbon sequestration? NOM NOM NOM.

The results of the latest iron fertilization experiment in the Southern Ocean are in – and it doesn’t look good as a solution for climate change. The Lohafex project, a collaboration between Indian and German scientists, found that merely stimulating a plankton bloom with iron did not lead to carbon sequestration.

What they were hoping would happen was this:

1. Iron input
2. Diatom bloom – diatoms have fast-sinking silica shells
3. Diatoms die & sink to bottom
4. Silica shells buried for all eternity
5. Carbon sequestration WIN!

What actually happened was this:

1. Iron input
2. Yummy Phaeocystis algae bloom – no silica shells
3. Copepods (tiny crustaceans) eat delicious soft algae.
4. Amphipods (small crustaceans) eat delicious crunchy copepods.
5. Copepods and amphipods respire, turning the algae right back into carbon dioxide.
6. Carbon sequestration LOSE.

Previous studies have shown that only 1-2% of sinking carbon (and that’s a generous estimate)  gets sequestered. There’s life in the deep midwater and life in the deep sea and all life is HUNGRY. (Personally, I blame the deep-sea sea cucumbers – those gluttons are major consumers of what little detritus makes it down there.)

Though the iron fertilization part of this cruise didn’t work out as desired, understanding nutrient cycling and plankton dynamics in the Southern Ocean is really important. As the polar ice melts it could cause nutrients to fluctuate, affecting the whales and squid and birds that all depend on Antarctic food sources. So please count me in for any future collaborations with Indian scientists! From the press release:

Spicy Indian curries were prepared at each meal by a Goan cook specially engaged for this cruise and contributed to the good atmosphere.

The authors claim that marine creatures will be unable to digest chewy terrestrial plants chock-full of lignin and cellulose, so the sea will keep that carbon down for thousands of years. If this worked, they calculate it would reduce carbon accumulation in the atmosphere by 15%.

Unfortunately, their entire premise might be wrong. The deep sea is not a lifeless cold dark empty place – it is filled with animals that are evolved to take advantage of whatever food drifts down from above, terrestrial or not. For example, wood that falls into the deep sea gets eaten. There’s even a deep-sea bivalve that specializes in drilling into wood.

Since wood is a lot harder on the digestion than grass stems, I doubt that all that crop waste would just sit there bereft and alone for thousands of years. It’s going to get munched upon and decomposed, and the carbon will go back into global circulation. I wish that controlling climate change were as simple as dumping some stuff nobody wants anyway into the ocean, but I just don’t think it’s going to be that easy.

Stuart E. Strand, Gregory Benford (2009). Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments. Environmental Science & Technology, 43 (4), 1000-1007.

Though iron fertilization is the best-known geoengineering proposal (thanks to Planktos’ shenanigans), there are several other serious methods under discussion. In a commentary published in Nature Geoscience in November, Philip Boyd summarized current geoengineering proposals and ranked them based on effectiveness, cost, risk, and time.

Here are the proposals Boyd ranked:

• Iron fertilization. Deliberately stimulating plant growth in the ocean with the aim that the excess material will be permanently sequestered in the deep sea. This would remove carbon from the atmosphere.
• Stratospheric aerosols. Injecting sulfer particles into the upper atmosphere to mimic a volcanic explosion and physically deflect sunlight. This would not remove carbon from the atmosphere, but would lower the overall amount of  heat reaching Earth.
• Cloud whitening. Spraying seawater droplets into marine clouds in order to increase their reflectance of sunlight. Like the stratospheric aerosols, this would not remove carbon from the atmosphere, but would lower the overall amount of  heat reaching Earth.
• Atmospheric carbon capture. Removing carbon from the atmosphere with a chemical absorbent (“scrubbers”) and then sequestering it.
• Geochemical carbon capture. Removing carbon from the atmosphere by using brine pools to transform it to a dissolved or solid state.

Boyd provides an handy, color-coded guide to the risks and benefits of each type of geoengineering. The more colored blocks a scheme has, the “better” it is.

Based on Boyd’s work, the highest-ranked proposal is cloud whitening. It has a reasonably solid rationale based on observations of ship tracks, it is reasonably affordable & safe, it would rapidly lower the Earth’s temperature if it worked (“mitigation rate”), and can be quickly stopped if there are unintended side effects (“emergency stop”).

The lowest-ranked proposal is (SHOCK!) iron fertilization. Though it has a relatively solid rationale based on experimental data, it has many unpredictable side effects and cannot easily be stopped in an emergency. Oh, and it probably won’t actually work.

Though Boyd’s ranking is certainly oversimplified – for example, cloud whitening, even if it worked, would do nothing to halt ocean acidification – that’s intentional. Boyd intends his system to be used as a logical starting point to figure out which geoengineering schemes deserve more research, and which should be trashed. He writes:

A transparent assessment should strive to increase public confidence in any selected tools, a prerequisite for tackling the difficult questions and complex issues raised by geopolitical, social and economic risks. Such an assessment of all of the
well-established proposals is urgently needed but so far entirely lacking.

Right now, I don’t feel confident in any of these proposals. I am dubious that we understand the ocean and atmosphere well enough to tinker with them. But since the nasty consequences of climate change are already coming fast and furious, I’m willing to listen to sober assessments of geoengineering risks and rewards. Just hold the pseudo-scientific hubris.

Thanks to Hao for the Wired article and Geoff for the geoengineering paper!

Philip W. Boyd (2008). Ranking geo-engineering schemes Nature Geoscience, 1 (11), 722-724 DOI: 10.1038/ngeo348

Planktos is now negotiating to buy private company Churchill Mining, which owns the rights to acquire and redevelop two copper properties in northeast British Columbia. Planktos then plans to change its name to Lobo Resources and secure $1 million in a private placement.

Perhaps it will be a cutting-edge environmentally responsible mining operation? Or…perhaps not.

Ah, Planktos. We hardly knew – actually, we knew ye quite well enough.

• Robo-fish! Finally the robo-lobsters and robo-lampreys have a friend!

• Flesh-eating slugs invade Wales. (No word on whether apophallation is on the menu, though.)

• Like a zombie risen from the grave, the trashy iron-fertilization company Planktos is ba-ack, and more incoherent than ever.

• I’m probably the last person on the internet to see the Dancing video, but I was absurdly touched. This guy went and did his stupid dance all around the world – 42 countries in 14 months. He danced with Australian crabs, cosplay girls, and even in the North Korean Demilitarized Zone.

Curtis Ebbesmeyer, an oceanographer based in Seattle, Wash., said when a human body submerged in the ocean, the main parts like arms, legs, hands, feet and the head are usually what come off the body.

But he’s still baffled by how the exact same part — a right foot — could wash up repeatedly.

“It’s not unusual for body parts to wash up along the United States or Canada,” he said. “There’s so many accidents, like boating. That’s not unusual. It is unusual to find four bodies over the course of the year and just right feet.”

He said his theory is that the feet came along as a result of an accident that might have happened up along the Fraser River, that washed down and spread out along the Straight of Georgia.

Ebbesmeyer said he would urge the police to trace the shoes back to the store they were purchased.

“There’s a lot you can do with the serial number of a shoe and I’m assuming the RCMP are doing that,” he said.

Thanks to Rick for the heads-up and the high-five! Now let’s keep our beady little crusader eyeballs on Australia’s Ocean Nourishment Company, which is apparently still in the urea-dumping business.

The ability of a given poop to store carbon depends on its sinking rate. The ocean is an average of 2 1/2 miles (or 4,000 meters) deep, and a poop has got to make it all the way down if its carbon is going to get stored. If the poop sinks slowly, there’s lots of time for it to get eaten or degraded by bacteria, which means that the carbon is released back into the water. If the poop is sinks quickly, more of that carbon will make it to the deep sea, where it has the potential to be stored for millennia.

The critter with the fastest poop in the sea is the noble salp. Salps are filter-feeders that float about in the open sea, feeding off whatever gets sucked into their siphons. (Incidentally, they are our closest invertebrate relative. They have a primitive spinal cord as a wee tadpole, but lose it on adulthood. There’s a metaphor in there somewhere.) And salps have seriously dense poop. Their poop can sink up to 1,000 meters a day, making it to the sea floor in a matter of a few days rather than weeks or months.

And there can be a LOT of salps. When conditions are right, they can form massive blooms that eat up to 75% of all the plankton they encounter. And that’s the problem – a salp bloom doesn’t leave much food for anyone else, particularly the tiny crustaceans favored by fish and whales. This is of particular concern in the Antarctic, where salps have increased while krill (what whales eat) has decreased.

So where does this leave climate change? The ocean fertilization people want to deliberately breed salps for their carbon storage capabilities. It is likely that a massive injection of salp poop would store a lot of carbon – but at what cost? Then again, all those little crustaceans may not be able to form their shells anyway in a couple years, so maybe salps are the future. I hear people eat salps in Korea – factory-farmed salp, anyone?

Thus with a whimper and a splash ends Poop Day. May your muffins be fibrous, your intestinal flora vigorous, and your bowels cheerful.

My Dad is a professor of physiology and a marine scientist. He reckons that if everyone ate oysters this would help global warming through shell sequestration. Do you know of anyone who works on this idea? ie could we use oysters, corals or possibly (excuse me if this is blasphemy) genetically engineered organisms to make calcium carbonate which we could then bury in the soil.? I am having trouble finding info about this.

I hereby dub this proposal “Oyster World,” and I sure do wish it were feasible. I LOVE to eat oysters (not to mention mussels, clams, and shelled critters of all kind. I am a bad, bad Jew.) However, Oyster World would not work, for the reasons I’ve listed below in order of least to most scary.

1) Oysters and corals are animals that respire. That is, they breathe in oxygen and breathe out CO2. So growing lots and lots of oysters would actually add some CO2 to the water. I don’t know how this balances with the amount of carbon stored in the shell matrix, but it would definitely lessen the carbon storage impact of Oyster World.

2) Oyster World would also be thwarted by the balance of carbon ions in the ocean. In order to form calcium carbonate shells, critters need both calcium ions and carbonate ions. Here’s the chemical equation:

Ca⁺ + CO₃^- –> CaCO₃

There’s a lot of calcium ions in the ocean, so that’s usually not a problem. But carbonate ions are a little harder to come by. That’s because most of the carbon ions in the ocean exist in the form of bicarbonate (HCO₃^-), which organisms cannot use. Here’s the equation:

CO₂ + CO₃^2- + H2O <-> 2 HCO₃^-

This is an oversimplification of a complicated set of reactions, but essentially it means that CO₂ and CO₃^2- are inversely related. If you’ve got a lot of CO₂, you’re only going to have a little CO₃^2-, and vice versa.

In Oyster World, we would make a lot of CaCO₃ shells,  and then remove them from the ocean. This would remove an important source of  CO₃^2- ions, which would increase the proportion of CO₂ ions. Unfortunately, increasing CO₂ in the ocean has a very nasty side effect…

3) Ocean Acidification (Or, the Terrifying Other Effect of Carbon Emission.)

So remember how increasing CO₂ decreases the CO₃^2- that our heroic oysters need to make shells? That’s what is happening right now. As more and more CO₂ is absorbed into the ocean, less and less CO₃^2- is available to anything that make a shell. This isn’t just oysters, but also corals, sea urchins, snails, lobsters, tiny shelled phytoplankton (foraminifera) – a vast swath of ocean life. Various studies have shown that critters have a hard time make shells when there isn’t enough carbonate around. And here’s the really scary part – in 2099, nothing that needs a shell may be able to live in huge areas of the ocean.

To illustrate this, here’s a map from Woods Hole Oceanographic Institute. (This map also appeared in “An Inconvenient Truth,” as some of you might recall.) The purple, red, and orange is enough carbonate to make shells for oysters & friends, yellow is tough but possible, green and blue means not enough carbonate to live.

Not only is Oyster World an unlikely solution to global warming, but the oysters themselves could be in future trouble.

Here are some resources to get you started. I am not sure how much science training you have, so I’ve included a selection of different sources.

• “A Chemical Imbalance”, from the excellent Altered Oceans series in the LA Times.
• A technical but accessible summary of the acidification chemistry from RealClimate
• The Ocean Acidification Network
• If you want to get into the scientific literature, this is a tiny sample of what’s out there:
  • Caldeira, K., and Wickett, M.E. Anthropogenic carbon and ocean pH. Nature: 425, 365, 2003.
  • Orr et. al. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437, 681-686 (29 September 2005).