NK Jemisin tweeted this article this morning with an appended “Oh no:” massive (and it seems illegal) ocean fertilization project taking place off the coast of Canada. (And a little follow up here.) Oh no indeed. This is scientifically problematic for a lot of reasons, the two main ones being a) algal blooms ain’t exactly great for the surrounding waters and b) it most likely won’t have the intended effect. (And this doesn’t even touch on the grossness of the pretense used to convince the indigenous people in the area to go for it, that it was supposedly about the salmon population.)
Let me give you some background.
First off, “ocean fertilization” is the process of dumping some kind of nutrient that normally limits planktonic growth into an area of the ocean, thus letting the little guys eat their fill, have wild plankton sex, and increase their numbers rapidly. This works because basically every bit of the ocean has its planktonic growth limited by the scarcity of one or more nutrient (e.g.: Rivkin and Anderson, 1997); otherwise the oceans would be one giant algal matt. In some areas it’s nitrogen, in some it’s phosphate, in some it’s iron (because iron is necessary for photosynthesis).
Okay, so why do it?
The theory here is that the planktonic organisms (since there is more to ecosystem than algae, even if they’re the ones sucking up the iron for photosynthesis) contain carbon. Living things tend to do that. Additionally, quite a few planktonic organisms build themselves shells or internal structures from calcium carbonate, which also pulls carbon from the surrounding water. So a surge in these organisms should suck carbon out of the atmosphere and ocean waters, right? Then the organisms die, fall through the water column as marine snow, and take all the carbon with them. They get to the bottom waters, get buried, and hey presto, that carbon is now out of the short-term carbon cycle and into the long-term carbon cycle.
Because of course, the problems we are having right now are quite literally caused by us taking carbon from the long-term cycle and releasing it into the short term cycle at prodigious rates.
So why wouldn’t that work?
We actually talked about this topic when I took Oceanic Geochemistry about a year and a half ago. It sounds very simple on paper, like it really ought to work. However, recent research has shown that it might decrease planktonic populations long-term (not good) and that diatoms might suck up all the iron anyway, because diatoms are basically the freeloading college roommate of the plankton world, you know, like that guy who always drank all the beer in the fridge and never replaced it.
There’s an even more basic issue with the idea, however. In order for carbon to get into the long-term cycle, it needs to be buried, and before critters have the chance to eat it. The oceans are teeming with life, most of which are single-celled eukaryotic organisms and bacteria, who just love to eat anything organic. Even at the beginning of burial, when oxygen content is almost non-existent in the sediments, there are plenty of anaerobic bacteria who will just keep munching away and effectively poop out pyrite. (The process is far more complicated than that, of course, but there’s a reason you tend to see a lot of pyrite in super organic-rich shales. Or in shales that used to be organic-rich before the bacteria came along and ruined your life.)
For a long time the model of how sufficient carbon could be buried to give us our lovely black oil-producing shales depended on anoxic events (literally, no oxygen in the bottom waters), but it really seems to depend more on just burial rate. The way to get the carbon buried and out of the way is to inundate the bottom sediments with so much that the bacteria can’t possibly eat it all.
So then in order for this ocean fertilization idea to work, you’d have to up the productivity sufficiently and for a long enough period of time that you could provide a buffet so large for the organisms in the water column that they can’t possibly eat it all. Then
you could actually bury the carbon, instead of just giving some really good meals to benthic critters who will then die and put their carbon right back into the short term cycle. If you, you know, don’t manage to kill most of the higher life in your surrounding waters with the algal blooms as well.
That’s my understanding of why ocean fertilization hasn’t been seriously pursued as a potentially climate-saving geoengineering project. I am also not, however, an oceanographer or geochemist, so I may be missing something here. If I am, I’d love to hear from you.
Also, a side note. If you google geoengineering, it’s frighteningly easy to fall down the rabbit hole of chemtrail conspiracy nut sites. Have fun.