January 11, 2020/David P. Turner
Gaia was originally a figure from Greek mythology: the mother goddess who gave birth to the sky, the mountains, and the sea. Gaia was adopted by the Romans when they conquered the Mediterranean basin, but her myth was largely abandoned with the ascendency of Christianity by the third century CE.
The first revival of Gaia was a product of the nascent Earth system science community in the 1970s. Atmospheric chemist James Lovelock was impressed by the finding of geologists that life had persisted on Earth for over 3 billion years despite a 25% increase in the strength of solar radiation (associated with an aging sun), and numerous catastrophic collisions with asteroids. He also understood that the chemistry of the atmosphere − which provides oxygen for animal respiration, protection from toxic solar UV-B radiation, and influences the global climate − was maintained by the metabolism of the biosphere.
These observations led him to suggest that the Earth as a whole was in a sense homeostatic, it was able to maintain certain life enhancing properties in the face of significant perturbations.
In casting around for a name to give this organism-like version of the planet, he was inspired by author William Golding to revive the term Gaia. Lovelock and microbiologist Lynn Margulis went on to write many influential peer-reviewed papers, and later books, on Gaia.
By the 1990s, the question of what regulated the functioning of the Earth system had become of more than academic interest. Earth system scientists had observed that the Earth system was changing and begun to worry about possible impacts of those changes on the human enterprise. Concentrations of greenhouse gases were rising, stratospheric ozone was declining, and a wave of extinctions was sweeping the planet.
Geoscientists were initially intrigued by the Gaia Hypothesis about planetary homeostasis, hoping perhaps that Gaian homeostasis might save us from ourselves. But by around 2000 they had largely rejected Gaia as an entity. Many of the feedbacks in the Earth system (see my Teleological Feedback blog) were positive (amplifying climate change) rather than negative (damping), hence not contributing to homeostasis.
The second revival of Gaia came predominantly from scholars in the humanities. Historians typically begin human history about 10,000 years ago when humans adopted an agricultural way of life. However, the discovery that humans have recently begun to alter the global environment on a geologic scale changes everything (as activist Naomi Klein says). The Earth system is no longer a benevolent background state that will provide a growing humanity with unlimited resources. Earth has a Gaian history that is now imposed upon by human history. The new field of Big History aims to juxtapose the geologic and anthropocentric time frames.
Historians needed a term to evoke an Earth system that in a sense has its own agency, and scholars like science historian Bruno Latour and philosopher Isabelle Stengers settled on Gaia. They emphasized Gaia not as a nurturing mother, but rather a force that will smack humanity down if the current trajectory of global environmental change continues.
In a recent hybrid interpretation, geoscientist Tim Lenton and humanities scholar Bruno Latour have dubbed the newly revived Gaia as Gaia 2.0. This version refers to an Earth system on which a sentient species has evolved and begun to alter the planet but has collectively taken on the project of developing an advanced technological civilization (a technosphere) that will live on the planet sustainably. That means comprehensive renewable energy, nearly closed material cycling, conservation of biodiversity to support the background metabolism of Gaia 1.0, implementation of multiple strategies to moderate climate change, and forms of governance that facilitate self-regulation at multiple scales.