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Is the Earth a Sentient Being?

The whole may be more than the sum of its parts; and we're a very small part.

A world renowned biologist told me over breakfast one morning that great scientific advances do not begin with moments of sudden insight that elicit “Eureka," but with moments of puzzlement that produce a…..”Huh?”

In other words, things that suddenly make sense are less likely to revolutionize the way we look at the world than things that make no sense.

Discoveries that make sense tend to be consistent with our world view, while observations that make no sense challenge it, causing us to re-think fundamental assumptions and make quantum leaps in our understanding of nature.

Atmospheric scientist James Lovelock noticed several phenomena that made no sense, ultimately leading him to the radical conclusion that the Earth—despite having roughly 9 million different species of living organisms—behaves as a single living being.

Here’s what made no sense to Lovelock

  • The salinity (saltiness) of the oceans has remained at about 3.4% over a billion years, despite runoff from rivers that continuously adds salt to the oceans from land erosion.
  • The average temperature on earth has been relatively stable over the last billion years, despite a 30-40% increase in solar radiation striking the planet
  • Oxygen in the atmosphere climbed from almost nothing 2.5 billion years ago to 21% 600 million years ago, and has stayed at the level ever since.

Like all good scientists, Lovelock looked for the simplest explanation for the odd behavior of the atmosphere and oceans. He concluded that a single force was acting like a thermostat to keep environmental conditions on earth stable. This force, according to Lovelock, exerted negative feedback whenever ocean salinity, atmospheric temperature or gas composition exceeded certain limits.

Biological systems heavily rely on negative feedback to function properly. When our body is starved of oxygen, brainstem neurons cause our breathing to quicken. When we have too much oxygen (e.g. from hyperventilating), the same neurons slow our breathing. If salt concentration in our blood exceeds healthy levels, osmoreceptors in our hypothalamus activate, motivating us to drink fluids to bring the salt concentration back down. When we’re cold, other sensors in our hypothalamus turn on, causing us to shiver and generate heat from muscle contractions. When we get too hot, we sweat to shed excess heat.

Aware that all living organisms rely on such negative feedback mechanisms to survive, Lovelock began to suspect that biology—not physics, chemistry or geology—held the keys to understanding why conditions on Earth have remained constant over billions of years.

Just as our bodies have negative feedback loops that keep oxygen, salt and temperature within healthy limits, Lovelock reasoned that biological forces might somehow act on sky, land and oceans to keep oxygen, salt and temperature within healthy ranges for living organisms.

As he explored the concept, Lovelock discovered multiple ways that life on earth, acting as a single entity, might keep conditions on the planet within the “Goldilocks” zone where life can thrive.

  • Bacteria along shorelines can cause limestone to form and seal off salt lagoons that, through evaporation and sedimentation, remove salt from the ocean. And seabirds eat salt-containing marine life, depositing salt bearing waste onto the land.
  • When temperatures rise, ocean algae proliferate. These algae secrete sulphur bearing aerosols that seed cloud formation, which in turn leads to increased reflection of sunlight into space, cooling the planet.
  • If the percent of oxygen in the atmosphere increases to unhealthy levels (many organisms can’t tolerate high oxygen levels and too much oxygen can cause the atmosphere to ignite from lightning strikes), zooplankton and other organisms increase their oxygen consumption, releasing carbon compounds (such as methane) that react with oxygen to reduce its concentration. Increased oxygen also may cause more forest fires, which in turn consume lots of oxygen.

These discoveries lead Lovelock to formulate the “Gaia hypothesis” which argues that all life on the planet acts in concert through negative feedback loops to keep environmental conditions optimized for life. (Gaia, in Greek mythology was a goddess who personified Earth).

Gaia, in Lovelock's formulation is not necessarily a sentient being, but it has characteristics of a sentient being in that it senses threats to its welfare and changes its behavior to reduce those threats.

So, why does the Gaia hypothesis matter?

First, the idea that all life on the planet is connected as a single living organism challenges the notion of our individuality and perhaps, even our free will. Are all of our actions truly under our own control, or are we unconsciously moved by the unseen hand of life on the planet writ large? Why, for example, do human fertility rates drop in industrialized societies that spew out the most greenhouse gases? Could it be—at least in part—a negative feedback loop that tries to keep temperatures and atmospheric carbon levels down?

Second, the Gaia hypothesis implies that the Earth is forgiving of our excesses, at least up to a point. The current increase in global temperature has been accompanied by increased algal blooms in the ocean, which could increase cloud cover and sequester excess carbon dioxide from the atmosphere, exerting a restraining force on further temperature rises.

That’s the good news.

The bad news, according to Lovelock in The Revenge of Gaia, is that we can only bend the planet so far before it “breaks,” and we may have already passed the breaking point. As the earth warms and the icecaps melt, less sunlight is reflected, further increasing temperatures. This positive feedback loop will worsen as the permafrost in northern latitudes melts, releasing methane and other greenhouse gases which will further elevate global temperatures. The end result will be coastal flooding as sea levels rise, massive disruption of the food chain, and potentially, an enormous reduction in the human population.

Such population loss would, of course, reduce greenhouse gases and pollution, making conditions once again tolerable for life on the planet.

Put another way, Gaia could be exerting negative feedback on humans in order to restore a healthy balance. We're being voted off the island.

Now that’s an inconvenient truth!