“If life on Earth were suddenly to cease, all the hundred-plus elements that make up the surface, oceans, and atmosphere would react until no more reactions were possible, and a state close to chemical equilibrium was reached. The planet would become a hot, waterless, and inhospitable place.” James Lovelock

One thing that I often use for tag in my blog is the word Gaia. This is a loaded word so it’s best to really be clear in the way I use it. I don’t mean a conscious entity that is embodied in the Earth itself that so many people associate with Gaia. Rather I think of the scientific idea that was first set out by James Lovelock in his Gaia Hypothesis and later explored in the Earth System Sciences.

Let’s start with an experiment. Find a small object, say a penny, and hold it between your fingers above the ground. It is now in an energy rich state. Now drop that penny and watch it fall to the ground where it bounces, rolls, flips and/or slides to the ground and finally stops any movement. It is now in an energy poor state, no more energy is able to be extracted from it, unless the floor develops a hole where the penny can continue falling.

Here’s another image of energy rich and energy poor. Think of a car; the fuel that goes into it and the exhaust fumes that come out of it. The fuel is energy rich, ready to be transformed into kinetic energy. The exhaust fumes are energy poor, no more energy is able to be extracted for the car’s movement.

James Lovelock once worked with NASA to investigate if there was life on Mars. At some point he came up with the idea that perhaps the atmosphere of Mars could show signs of life by virtue of interacting with it. Mars’ atmosphere is energy poor, with chemicals comparable to a car’s exhaust fumes, whilst the Earth’s atmosphere has an energy rich chemistry. If the Earth had not developed lifeforms it would have fallen (like the penny) to the same fate as Mars, a dead, lifeless rock incapable of supporting or even developing life.

Somehow the collective action of life on Earth stops entropy from make the Earth irreversibly lifeless and keeps it inhabitable. Free energy from the Sun’s own entropic decay is “collected” by life through photosynthesis. This energy is exchanged with the environment, like the atmosphere, and with other organisms, where it takes on energy rich qualities in a balancing way that means that life can live on the Earth.

In a way it’s like having a system of organisms attached to your exhaust fumes that aborb those chemicals and, using the Sun’s energy, turn them into energy rich fuel that goes back into the car to power it, or another system of organisms that use the Sun’s energy to keep that penny in the air to stop it from falling to the ground, with the added bonus that by doing so it makes the existence of life possible.

That is a very simplistic explanation leaving out many details, which doesn’t do the theory any justice at all. I could talk about homeostasis, chemical equlibrium, disequilibrium, Daisyworld, the albedo effect, glacials, interglacials, the Milankovich effect, global warming, climate change, greenhouse gases,  defining life, neo-darwin evolution, Gaian evolution and other facts and theories that James Lovelock has woven together to create a compelling picture of the Earth’s life. All I want to do is introduce one aspect of it from which other aspects can be explored. My reference for this is James Lovelock’s Healing Gaia, though there’s plenty of other books about it, and lots of information on the internet. Just do a search of any of the terms I used above.

Gaia theory as a whole is just scientific theory, yet it is gaining credibility all the time, especially within Earth Systems Sciences. Parts of it have been proved and parts of it have yet to be proved.  So far it is the best image we have of the Earth as a self-sustaining system, an image that is being confirmed, modified and updated all the time by scientific research. But from this theory we can grasp a feeling of the world around us and how we fit in with it. Personally I have no doubts that Gaia Theory has something to it, that somehow the Earth is alive in some sense, that somehow it is an interdependent system and that there definately are consequences to our actions within it.