Lesson #1

The last time I wrote, I said I’d go into some of the particulars about research on the cruise. Well, after talking to Chris Measures of the Trace Metals team (and the University of Hawaii), I thought it’d be worth summarizing a conversation we had about something called the Gaia theory.

I’ll start from the basics: Captain Planet. Captain Planet, as you may or may not remember, was a nineties cartoon superhero powered by the combination of Earth, Fire, Water, Air, and Heart. He saved the world every Saturday morning, usually from the threat of ugly, fat adults. The Captain’s kryptonite was pollution, so plots usually centered on a group of five kids hosing slime off the Captain so he could get his powers back. Well, another less-well-remembered-but-interesting aspect of the cartoon was Gaia, the beautiful blue-green lady who hired Captain Planet in the first place. Actually I don’t remember what colors she was, but she was definitely pretty! Her name was a reference to the Greek goddess of the Earth, and also to Lovelock’s Gaia theory of the 1970s.

The Gaia theory was a popular theory that said the world is a vast, self-regulating organism: that nature is completely in harmony, and when something goes a bit out of whack (ex. global temperature goes up), then natural feedback loops correct the problem (ex. an ice age). The main concept was that a moralistic higher power oversaw the natural balance. It’s a pleasant theory, but has frequently been discredited as even more ridiculous than Captain Planet.

I mentioned this in an earlier post, but phytoplankton in the ocean have a large impact on carbon dioxide levels (by photosynthesis) in the ocean and thus the atmosphere, as limited by the amount of nutrients and micronutrients (such as iron) in the ocean. Well, iron is crucial to the respiratory processes of many living things. What’s interesting is that the oceans are relatively iron-deficient; it’s generally provided from dust blowing off continents and from the minerals in continental shelves. But there’s generally a lot more demand for iron than supply. So why do the phytoplankton have such a thirst for iron, when there’s not that much around? The answer is that there used to be a lot of iron, and that the plants originally evolved in an environment abundant with iron.

Iron has two oxidation states: a low-oxidation state and a high-oxidation state. The former is very soluble, the latter not. Only soluble iron is biologically useful. There used to be a lot of low-oxidized iron in the environment, and not a lot of oxygen: the world was anoxic back in the day. Well, then came the phytoplankton, which burned up tons of iron and converted tons of CO2 into oxygen, and by doing so created an oxygen-rich atmosphere. While humans would eventually appreciate this change, this process caused several planet-wide crises because all the surface iron reacted with the abundant oxygen into a high-oxidation state, which subsequently meant a lack of available, soluble iron for living things. This punches a hole in the Gaea theory: the phytoplankton wiped out the balance that had been in place in the anoxic world. Life changed in a big way, and hasn’t really returned to that original state. Was this a good thing? A bad thing? It’s not really for us to say.

Now this is not to say that negative feedback loops do not exist in nature. There’s an interesting one that came up a few years ago: when the sun strikes the ocean surface more (ie under warming conditions), the phytoplankton—being excited by ultraviolet light—release DMSP, which is a precursor to dimethyl sulfide (DMS). Dimethyl sulfide is related to cloud formation, which of course begins a cooling process by reflecting light and causing rain.

Actually, one of the main blocks to understanding climate are the clouds. You know how weather forecasters are always trying to tell you what to expect, and how they’re often wrong? Well, the fact is, no one really knows all that much about cloud formation. We know the basic concept: evaporation of water, or something, but they’re still a mystery. And they’re a key link: understanding clouds would tell us more about weather patterns, rainfall, and also about the amount of sunlight that’s getting through and warming the surface of the earth and the oceans. It’s all connected. It’s not necessarily in service of some all powerful Gaia force, or any other higher power; there’s no good or bad attached to these processes. They just are.