Ecological Twofer

By | September 13, 2005

I am convinced that the answer to global warming will be found in biology. Nothing that we can do outside of biology can benefit the environment as readily as biology itself. Imagine trying to come up with a mechanical solution for global warming. The space shield idea, for example, is a nonstarter. We will have to harness nature to work on its own behalf.

J. Craig Venter seems to agree. Venter, who is famous for racing the government to map the human genome, started a new company in June called Synthetic Genomics. As usual, Venter has big plans:

A host cell that has reduced and reoriented metabolic needs can generate biological energy applicable to a broad range of industrial fields including energy, industrial organic compounds, pharmaceuticals, CO2 sequestration, fine chemicals, and environmental remediation. “We are in an era of rapid advances in science and are beginning the transition from being able to not only read genetic code, but are now moving to the early stages of being able to write code,” said Dr. Venter.

Instead of old style genetic engineering where sniplets of DNA were thrown at a genome hoping it sticks, Venter is working on a modular construction system for DNA. Advances in this field are moving forward very quickly. The first announcement that this level of genetic tinkering was even possible was earlier this year.

In Venter’s laundry list of potential applications, a couple of possibilities stood out for me: “CO2 sequestration,” and “environmental remediation.”

At a lecture more than a decade ago, [oceanographer John Martin] declared: “Give me a half-tanker of iron, and I will give you an ice age.” He was alluding to the fact that the Southern Ocean is packed with minerals and nutrients but strangely devoid of sea life. Martin had concluded that the ocean was anemic—containing very little iron, an essential nutrient for plankton growth. Adding iron, Martin believed, would cool the planet by triggering blooms of CO2-consuming plankton.

Subsequent testing has shown that small amounts of iron can encourage the growth of huge plankton blooms in the Southern Ocean. John Martin added, “Even if the process is only 1 percent efficient, you just sequestered half a ton of carbon for a dime.”

Nature is more efficient than we could hope to be with any mechanical sequestering project. That’s not to say that natural plankton blooms couldn’t be improved upon. Instead of depending upon natural selection or breeding, perhaps plankton could be rebuilt with Venter’s methods to be more efficient in sequestering carbon.

But there might also be the possibility of a second benefit. Another part of our environmental crisis is the rise of acid levels in the ocean. The more acidic the oceans, the less coral reefs can grow, and this forms the base of the food chain – of the entire ecosystem.

The acid in the oceans is carbonic acid. This acid is the byproduct of the chemical reaction of CO2 and water.

It’s been suggested that one solution to the acidic oceans is to dump limestone into the ocean. But dumping limestone is another mechanical solution. It would be a hugely expensive undertaking to mine limestone and transport it to the ocean for dumping.

But, as fortune would have it, limestone is itself a form of sequestered CO2. Putting those two facts together (that limestone is form of sequestered CO2 AND that limestone is alkaline) suggests that these plankton blooms might have a dual benefit.

What if plankton (or a Venter-esque engineered improvement) could not only sequester CO2, but also provide an alkaline byproduct like lime?

Obviously, there are many questions to ask. Does plankton sequester the CO2 into an alkaline substance like limestone? If not, could it be engineered to do so, or do so more efficiently? Would this alkaline byproduct significantly alter the ocean’s pH for the better? Would the CO2 stay sequestered if it is also busy neutralizing carbonic acid?

Engineer Poet had additional thoughts and questions:

Calcium carbonate is only stable in seawater down to a certain depth; as pressure increases, it dissolves more and more easily. There are diatoms which build their shells out of calcium carbonate, but as they fall toward the bottom after dying their shells dissolve and go back into the water.

The fate of the rest of the biomass is another question. There are large food chains at the ocean bottom driven by the rain of dead organisms from above. If you add enough carbon to this to offset human fossil fuel consumption, will you have enough oxygen in the deep waters for the aerobic organisms? Will the deep ocean floor go anoxic and become one huge dead zone? I’d want to know before pushing this scheme further.

Absolutely. You’d want to know all this before beginning. Even then, it would be best to push forward incrementally in order to assess any unintended or unexpected consequences. That said, it is encouraging that Venter believes engineered life could help address CO2 sequestering and other environmental problems. He’s known for accomplishing lofty goals.

  • Phil Bowermaster

    On the global warming piece, is it a one-way switch? If the planet starts getting too cold can we somehow tell the plankton to knock it off?

  • Stephen Gordon


    For a small price I can install this little blue button to get you down.”

    Remember that we have to encourage the growth of plankton in the Southern ocean with iron supplementation. Just cut back on the iron and the plankton will die back.

  • Engineer-Poet

    I’ll bite:  why is the space shield a non-starter?  (I need to see if I can turn my plot concept into an SF story about that.)

    It occurs to me that the issue of deep-water oxygen depletion is a non-issue if most of the organic matter does not reach the deep ocean.  The antarctic has upwelling, but tropical oceans might yield even more if they were fed nutrient-laden water via e.g. OTEC.  And if the algae could be captured, or even turned into shrimp or fish protein, the potential productivity looks staggering.

    The difficulty seems to be engineering algal growth and capture systems which can tolerate the “high energy” environment (waves and storms) of the open ocean.

  • Pat

    You’re assuming that CO2 has a significant impact on global climate and that global warming is actually occurring beyond the range of fluctuations experienced since, say, the end of the last ice age. Both assumptions are dubious.

    Check out this chart of CO2 concentrations and global temperatures over the last 500 million years:


    Sequestering CO2 in a process that could run out of control might be far worse than the presumed harm of slight increases in CO2 concentrations. CO2 is best viewed as “plant-food in the sky”. No CO2 = no plants = no life.

    Burning fossil fuels is really just recycling Carbon back to where it came from hundreds of millions of years ago.

  • Stephen Gordon


    The technical hurdles of a space shield would be immense. It would be a much bigger project than a space elevator – which you’d almost certainly have to have to make the project even close to feasible.

    You get a space elevator (or many elevators) to get the material into orbit, and then have the shield self-assemble – then, maybe.

    That’s a bit out of our reach at the moment. Plankton farming seems to be, quite literally, lower hanging fruit.


  • Engineer-Poet

    There’s no reason for all the material for a space shield to be hoisted up from Earth; there’s plenty floating around in space.

    Plankton farming is not going to be able to offset greenhouse warming due to methane emissions from e.g. Siberian permafrost dumping its clathrates.  It takes about ten years to decompose to CO2, but there’s not much that could be done in the mean time.

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