Gaia

The idea of planet Earth as a resilient ecological system, able to maintain its environment in a state consistent with its needs.

In the early 1970s, the scientist James Lovelock suggested that the planet’s living ecology regulates its atmosphere and temperature to shape the conditions it lives in. It does not merely adapt to change; it influences change. It makes its planet inhabitable. At the suggestion of the novelist William Golding, Lovelock named this phenomenon after the Greek goddess of Earth, Gaia.^G1

Though ridiculed at first, Lovelock began to give it substance as a theoretical model with his Daisyworld, whose temperature is regulated by daisies. Imagine a planet on which only one kind of plant grows: daisies, which come in two kinds: white and black. The white ones cope best in warm conditions because they reflect sunlight back into space, and this keeps both themselves and the planet cool. The black ones cope best in cool conditions because they absorb heat, and this keeps both them and the planet warm. Now imagine that, at the start of the story, the sun (as has happened in fact) gives out substantially less heat than at present, so that the planet would be quite cold, were it not covered by black daisies which absorb much of the heat. However, the sun gradually warms up; conditions become hotter and less favourable for the black daisies and more favourable for the white ones, so white daisies increase, black ones diminish, and the temperature of the Earth remains benign for daisies. This continues until the surface is entirely covered with white daisies.

Then comes the turning point. As the sun now gets even hotter, there are no black daisies left to replace. Just a small further increase in heat from the sun is too much even for the white daisies, which die off—and there is nothing to stop the planet heating up beyond the range of the daisies to do anything about it. And that, for the simple computer model with its virtual daisies, is the end of the story. In a real ecology, with complex relationships between millions of species, other kinds of interaction between the living members of the ecology and their material setting—its rocks, water and (mainly solar) power supply—will kick in, conserving the favourable conditions despite the external shock. But even with millions of species on the case, there comes a point where a shock—such as the heating up of the sun, or the relentless loading of carbon into the atmosphere by an industrial civilisation—reaches the limits of Gaia’s resilience.^G2

That is what you might expect. What is much less obvious is that life itself, in the process of taking part in the web of interactions and feedbacks which sustains and is sustained by Gaia, can take forms and present problems which are beyond Gaia’s ability to cope. For example, some 2.3 billion years ago, microbes mastered the art of photosynthesis (the extraction of carbon from carbon dioxide, and the release of oxygen as a by-product). That was a brilliant breakthrough. However, those microbes then proceeded to suck up so much carbon dioxide that the Earth lost its ability to conserve heat, and the oceans froze solid for 100 million years. The same thing happened again (700 million years ago), when complex plants (i.e., plants with leaves and roots) evolved which not only absorbed carbon dioxide but speeded-up “weathering”. Weathering is the process which wears away rock and releases phosphorus and other vital ingredients of a fertile soil—a good Gaia-like thing to do, you might think. But it takes a lot of carbon out of the atmosphere in the process. Result: another 50 million years of ice.^G3

Could it be, then, that Gaia has a self-destructive side to her character? Consider: Gaia produced Homo sapiens . . .

Gaia is, without doubt, the benign vitality which gives us resilience. But success, in the form of life itself, can lead on to shock. We can think of this either as the other side to Gaia’s character, or as the work of a quite different character: Medea, perhaps. Medea was the enchantress—grand-daughter of the sun-god, Helios—who tricked the daughters of Pelias into boiling their father alive.^G4 She seems at first, with a cv like that, to stand for disorder to an extreme degree, but she is in fact quite law-abiding, by the standards of a goddess. Unfortunately, the law she abides by is the “Power Law”, which says that the scale of shocks a system will suffer over time ranges in scale from the trivial (most shocks), and the moderate (some shocks), through to the rare but utterly breathtaking and cataclysmic. The Power Law tells us that failure is intrinsic to all complex systems, and to resilience (Systems Thinking > Form > The Power Law).

This succession of death and life is the time-signature of Lean Logic; it is present in lean thinking, with its radical break followed by slow incremental development, and in the cycle of release and regeneration in the Wheel of Life. A resilient ecology extends its collective lifetime by allowing parts to go through their Gaia-Medea cycles on a smaller, less destructive, scale (Sacrifice-and-Succession). It can be a highly successful strategy, sustaining interlocking cycles of depth and renewal for long periods. It is with its breathing-out and breathing-in, its sigh and inspiration, that the system as a whole keeps going. Life doesn’t give up easily, since it is almost infinitely adaptable, and capable of inventing and sustaining interactions favourable for life. For any particular form of life and ecological community, however, prospects are less assured.

And yet, consider dimethyl sulphide (DMS). Or, rather, consider, dimethylsulphoniopropionate (DMSP). DMSP, as its name suggests, is a long molecule, and it is found in the cells of marine organisms such as Emiliania huxleyi—abundant algae which are known for capturing carbon from the atmosphere and precipitating it to the ocean floor as chalk. The DMSP in the algae’s cells keeps them from losing water by osmosis to the surrounding sea, but when the cells die DMSP degrades into DMS, which then floats up into the atmosphere (giving the sea its slightly tangy sulphuric smell) and degrades, leaving a residue of sulphate aerosol. This has the effect of ‘seeding’ clouds, meaning that, sooner or later, it will rain.^G5

So the algae’s cells contain the DMSP, which releases the DMS, which seeds the clouds, which make it rain. But the algae itself depends on iron in the sea, which is scarce. Here peat bogs come to the rescue. When sphagnum moss there dies, it releases humic and fulvic acids which, in effect, pickle it, storing carbon and building up a deep layer of soggy black peat. These acids also get to work dissolving the metals, including iron, out of the bedrock, and the iron-rich solution then drains into the rivers and thus into the sea, where it fertilises the algae which in turn make it rain.^G6

Meanwhile, down in the forest, bromeliads, small plants that live on trees, have leaves (technically, bracts) specially shaped to catch and hold pools of water, which are alive with bacteria and algae which maintain their own wetness with DMSP, which breaks down to DMS, which makes it rain. That rain turns the tropical forests into a heat pump, driving up warm, wet air into the atmosphere, where it is transported by (the Walker and Hadley) air circulations far into the Northern and Southern Hemispheres, cooling the forests enough to keep them near their optimum temperature, and distributing heat to parts of the planet which, without them, would freeze.^G7

All told, we do seem to get a lot of benefits from the decomposing waste products of a chemical used by the cells in algae to keep themselves wet. And yet such connected and unlikely elegance is everywhere. Every ecosystem, from the human body to slime mould to heathland, has connections and interactions in support of constancy. Any accident of nature whose outcome sustains these conditions is likely to happen again. Accidents of this kind reinforce themselves, steering the system they live in with constant adjustments of positive and negative feedback, maintaining the subtle conditions for life of a particular kind.^G8

That particularity will not last indefinitely, but Gaia’s stabilising feedbacks can keep a system in an apparently unlikely condition for a long time. It will have started by accident, but its feedbacks make it seem intentional, giving it, it seems, a guiding hand, a stillness and integrity. What seems like purpose is in fact a more secure and reliable thing—a system stuck in a benign and brilliant rut. Gaia settles in. Medea bides her time. For now.

Related entries:

Emergence, Climate Change, Wheel of Life, Good Shepherd Paradox, Spirit.