What on Earth is Ocean Seeding?

It seems like, as of late, I tend to open posts with some commentary about the relative superluminal passage of time but it's actually more than just introductory banter this time around! Even though it's crazy to think that Gen Con is already some two weeks gone and fall semester is right around the corner, these remarks are to set you up for something we've chatted about in fictional theory, but not in real-time practice. Let's get ready for some science! Here in the northern hemisphere we're approaching the "last weekend of summer", a label which I firmly refute and instead adhere to the autumnal equinox as the official transition to fall. New England autumns are lovely, but there's no need to curtail our already too-short summer.

The equinox is also the traditional endpoint assigned to several major climatological indicators, not least of which is a measure that has received a fair amount of press in the past week: the area of the Arctic Ocean covered by ice. For the past few years, between now and the onset of calendrical autumn, we've been peppered with reports concerning the Arctic ice shield that tend to pose the same questions. How fast is it melting? How many square miles/kilometers remain as ice by mid-September? How quickly or slowly does the shield reform after melting? This year this icy layer reached a record low of 4.10 million square kilometers (1.58 million square miles)[1] with a whopping three weeks remaining until the equinox (the endpoint of the 'melt' season). This mark surpassed the previous record low set back in 2007 when the Northwest Passage opened for the first time in human memory[2]. More distressingly, what little ice remains is not the solid cap seen at most other points in the year, but is a permeable mélange of icebergs, flows, and heavy slush. This composition will impede the reformation of the cap in colder months and is only one of several positive feedback loops associated with climate change in the Arctic.

Just a few years ago there would have been no water in this shot

I study this stuff as part of my graduate school curriculum and I often seek to check the ever-encroaching, highly isolating bubble of academia by discussing these matters with people who don't read about  thermohaline circulation for kicks. These conversations almost always immediately take on one of four tacks:

-         We don't know enough about this stuff yet/the science isn't conclusive.
-         Climate Change has happened before and will happen again with or without human intercession.
-         OMG! This is monstrously terrible! The polar bears are drowning! We have doomed ourselves to a steamy, insect-filled fate.
-         Yeah, that's bad and all, but what can we really do about it? Even if I change my habits it's not going to make that big a difference right?

That last would-be argument, I feel, best captures the sentiments of the majority of people observing the changes that are going on around us. Even cursory Denialists will concede that even if climate change is upon us and humans have a hand in it what can really be done about it at this point. Most of us have an idea of what's going on and what it would take to be a good global citizen, but it's hard not to be skeptical about the ameliorative properties associated with recycling a can of Mountain Dew or remembering to turn off the lights as you leave a room. This is not to say that the contributions resulting from mindful action on the part of individuals is insignificant, far from it. We all do need to do our part to keep this planetary ship afloat and habitable, but you'd be correct if you said that all our composting and use of compact fluorescent lights wouldn't be enough to dial down the Earthly thermostat. Studies attempting to quantify and qualify exactly what and how much we would need to do are inconsistent at best, as the rate of change is continually in flux, making the creation of a viable model extremely difficult.

None of this sounds good in the slightest. Surely someone has to have come up with something by now!

You would, once again, be right.

Potential ideas for the mitigation of or adaptation to the processes and effects associated with climate change have sprung up from a myriad of sources, from university researchers and corporations to municipalities and single inventors. Many of these innovations are still in the experimental stages or are mired in the lengthy process of securing protection for intellectual property. So what is out there that works?

One promising but controversial technique is Ocean Seeding (aka Ocean Fertilization or Micronutrient Fertilization). Though there are several ways go about seeding the oceans, the majority of these methods hinge on the same mechanic: stimulating aquatic primary production to act as a giant carbon sink. Say what now?

We all know that we inhale gaseous oxygen and plants (primary producers, or the base of the food chain) do the same with carbon dioxide. Carbon dioxide is the most plentiful of the greenhouse gases. Anything that can capture and sequester carbon dioxide can be termed a 'carbon sink'. Hence, plants can act as a carbon sink. Unfortunately, agriculture, industry, and climate shifts, among many other things, have limited the quantity of land-based plant life. The plants do a great job of vacuuming up carbon dioxide, there just aren't enough of them to take up the amount of carbon dioxide that gets pumped into the air every day. So we need a lot of space that can bear plant life but currently doesn't. Well we have this giant series of salty, watery things that cover the vast majority of the planet that could support primary production but currently lack the nutrients to do so.

That's the premise behind Ocean seeding: introducing nutrients into the ocean to support the growth of phytoplankton which, in turn, sequester carbon dioxide via their vital processes. When the phytoplankton die their bodies continue to hold onto the carbon dioxide (think bark on a microscopic tree) and descend to the ocean floor or are incorporated into the tissues of whatever creature ate them. When the carbon is eventually released (centuries later), it likely will not be gaseous, but in a form and on a timetable that the planet can work with.

The pictoral gist of how this should work
 So…why are we not doing this again?

One of the reasons we don't see ships heading off to dump tons of minerals into patches of ocean right this minute is that the jury is still out on the best nutrients for the job and the quantities that would be required to produce the desired effect. Pulverized phosphorous, urea, and iron are the current favorites, as these effectively simulate the particulate matter that gets blown into the sea from the land every day. Only this past summer did scientists release evidence that iron may be the most effective at fostering colonies of phytoplankton, as the carbon-to-iron ratios in the plankton are far higher than any other than any other such carbon + other element combination. Fertilization with iron has been estimated to translate into up to 0.29W/m2 of 'negative forcing', essentially the equivalent of removing 1/6th of current carbon emissions from the atmosphere.[3] Further studies will need to be conducted to confirm this, but the potential applications would be just the kind of mass attenuation that the Earth needs right now.

Oceanic nutrient levels (dark blue is low levels, red dots are experiment sites).

Other variants of ocean seeding include cultivating large quantities of phytoplankton or algae in large holding pen devices on land or ship, then lowering these into specific areas of the ocean, or developing strains of phytoplankton that emit sulfate aerosols to help boost the reflective power of the atmosphere (thus sending more solar radiation back into space). Both of these methods are, as you can imagine, a bit more involved than direct marine mineral application and few organizations are currently endeavoring to conduct large scale experiments, so it will be some time before we can get an idea of their efficacy.

Of course, geo or hydroengineering on such a large scale is not without consequence and those effects are largely our best guesstimates at the moment. Some of these could be positive. Aside from ostensibly sequestering carbon dioxide, ocean seeding has the potential to help regulate marine pH (reversing some of the ocean acidification that has occurred as a result of climate change), replenish phytoplankton stocks, which have been in decline since 1950, and introduce food stores to largely lifeless areas of the seas. However, ecologists worry that cultivating mass quantities of phytoplankton could create harmful algal blooms (like red tide), deplete deep water oxygen levels, or send unintended ripples through the food chain. Furthermore, many scientists believe that a cocktail of several nutrients (most commonly silicic acid) and very specific oceanic conditions will be required for seeding to function as intended. The actual monetary costs of effective ocean fertilization are also a source of contention, as supertanker-sized quantities of minerals tend not to come cheap.

We have a lot of work to do before the applications and feasibility of ocean seeding/fertilization can be truly discerned, but don't be surprised to see it pop onto your news feed in the near future. It's far from perfect, but it may be a start.

[1] National Snow and Ice Data Center. (2012). "Arctic Sea Ice Breaks Lowest Extent on Record." http://nsidc.org/news/press/20120827_2012extentbreaks2007record.html
[2]  National Snow and Ice Data Center. (2007) "Arctic Sea Ice Shatters All Previous Record Lows – Diminished summer sea ice leads to opening of the fabled Northwest Passage"
[3] Lenton, T. M., Vaughan, N. E. (2009). "The radiative forcing potential of different climate geoengineering options". Atmos. Chem. Phys. Discuss. 9: 2559–2608. doi:10.5194/acpd-9-2559-2009. http://www.atmos-chem-phys-discuss.net/9/2559/2009/acpd-9-2559-2009.pdf.

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