Plankton and carbon dioxide

There’s been a lot of buzz around lately regarding the use of plankton as a means of reducing carbon dioxide in the atmosphere.

The oceans of the world absorb a great deal of carbon dioxide. The problem is that some bodies of water, such as the Southern Ocean, have become saturated in carbon to they point they are becoming acidic.

Temperatures of oceans are also increasing while wind borne micronutrients such as iron delivered to the ocean are decreasing. These factors are decimating plankton populations – and plankton also help remove carbon dioxide from the atmosphere in addition to being a food source for other marine animals.

These sorts of scenarios are called positive feedback loops, where one undesirable scenario affects another which in turn accelerates and exacerbates the original problem – and adds more issues which in turn create other feedback loops. It highlights the fact that everything in nature is connected.

A company called Planktos states that by replenishing plankton populations, much of the world’s excess carbon dioxide can be dealt with. Plankton convert carbon dioxide into carbon stored in their bodies and when they die or are consumed, that carbon is in turn either stored in a predator or sinks to the bottom of the ocean.

In a trial to be run shortly, Planktos will drop 100 tonnes of powdered iron into the ocean west of the Galapagos Islands with the goal of creating a very concentrated plankton bloom and then monitoring the results.

It’s all fascinating stuff, but when I first heard about it an old nursery rhyme came to mind – the one about the woman swallowing a fly, then swallowing a spider to catch the fly, then swallowing a bird to catch the spider, and so on and so on until she swallowed a horse, which of course killed her.

I’m certainly not a scientist, but some scientists familiar with the idea have raised questions as to the effectiveness of the concept, stated that it would have to be done on a massive scale repeatedly and are concerned about the wider ecological impacts of such an ambitious program.

But then again, is what Planktos proposes really any different to planting more trees to try and decrease carbon dioxide levels? Might we be buying plankton offsets in the near future?

What a world  and mess we’ve created for ourselves.