Jun
16
2010

The iron poop of whales will save the world

A sperm whale: You will never get my precious iron feces! Never!
A sperm whale: You will never get my precious iron feces! Never!Courtesy Pacman
It would be a very special day indeed if a better story than this one popped up. But I wouldn’t ask for that. How could you want any more than this: whale poop fights global warming*.

Sperm whales are the particular focus of this study. The population of sperm whales in the Southern Ocean (the waters around Antarctica) is thought to be about 12,000. (There are more sperm whales in the world, but the study looked at Southern Ocean sperm whales.) Those 12,000 whales are thought to put about 200,000 metric tons of the greenhouse gas carbon dioxide into the atmosphere each year. That’s about the same amount that 40,000 passenger cars contribute each year. Destroy those polluting whales, right?

Wrong! See, it turns out that these sperm whales are also responsible for the removal of 400,000 metric tons of CO2 each year, making up for the amount they produce two times over. Their secret is this: they poop iron.

They don’t only poop iron, but sperm whales poop a lot of iron—each whale is thought to defecate about 50 metric tons of iron each year. That’s over 300 pounds a day! Obviously the whales aren’t pooping out solid iron ingots, though. It’s mixed in with their liquid feces. And that’s important.

The whales themselves don’t remove those 400,000 tons of CO2. They’re removed by phytoplankton. Phytoplankton are microscopic organisms that, like plants, use sunlight and CO2 to build their bodies. And they feed on iron.

The whales have lots of iron in their diets, because of the large amounts of fish and squid they eat. So the iron-rich whale poop is an ideal nutrient for phytoplankton. When the phytoplankton dies, the carbon they contain falls to the bottom of the ocean instead of being released back into the atmosphere. Where more carbon is trapped than is released back into the atmosphere, it’s called a “carbon sink,” and that’s what whale poop and phytoplankton create in the Southern Ocean.

Other parts of the ocean may naturally contain more iron for phytoplankton, but the Southern Ocean is poor in the nutrient, and the microorganisms rely on an iron cycle that the whales apparently play a large part in. More whales, greater carbon sink. Fewer whales, less whale poop, more atmospheric carbon.

Coincidentally, the International Whaling Commission will be meeting next week, to discuss regulations on how many whales can be harvested from the oceans each year. It’s a complicated world, isn’t it?

*I thought about making the headline “Whale poop is ‘green’” but… yuck.

Your Comments, Thoughts, Questions, Ideas

Shana's picture
Shana says:

Somehow I don't think this is going to make it into the save the whales campaign...

posted on Wed, 06/23/2010 - 12:46pm
Anonymous's picture
Anonymous says:

Why not? Seems pretty significant to me!

posted on Sun, 10/24/2010 - 10:11pm
JGordon's picture
JGordon says:

I just realized that more than two paragraphs are missing from this post, thanks to my poor html skills. Nice proof-reading, jgordon. (It's fixed now, but... literally several people got a sub-par Buzz experience here.)

posted on Wed, 10/13/2010 - 3:01pm

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