The GAIA hypothesis: a New Look at Life on

Earth

CSCI 1210

Fall 2003

James Lovelock

British atmospheric scientist

Invented electron capture detector

Discovered presence of CFC’s in atmosphere of remote regions

Lovelock’s “Discovery” of Gaia

In 1960 Lovelock was asked to design an instrument to be landed on Mars and detect Martian life by sampling the Martian atmosphere.

Lovelock asked, “What is life? And how does it affect the atmosphere?”

Lovelock’s “Discovery” of Gaia

Using telescopic data, Lovelock and a colleague analyzed the atmospheres of Earth, Venus, and Mars

The results showed that the atmospheres of Venus and Mars are in chemical equilibrium, but the atmosphere of Earth is far from equilibrium

Atmospheric compositionshttp://www.prototista.org/E-Zine/evidenceatmosphericdiseq.htm

Gas Earth Venus Mars

CO2 0.03% 96.5% 95%

O2 21% Trace 0.13%

N2 79% 3.5% 2.7%

Interpretation?

Mars and Venus, which are similar planets, have very similar atmospheres

Earth is similar to Mars and Venus, except for one major difference: LIFE.

LIFE is responsible for maintaining Earth’s atmosphere in a non-equilibrium state

Temperature regulation

Astrophysical theory suggests that the Sun’s luminosity should have increased 25% - 70% over past 4.5 billlion yearsHowever, Earth’s temperature has remained roughly stable for that timeLovelock postulated a negative feedback loop: plants sucked CO2 from the atmosphere, reducing greenhouse effect.

Why this is radical

Traditional evolutionary theory: life exists in a predefined chemical environmentLovelock’s theory: life is controlling the physical environmentLife maintains the physical environment in a condition favorable to lifeNovelist William Golding suggested the term GAIA for this process.

Lynn MargulisYoungest woman ever admitted to the National Academy of Science

Her work on bacterial sediments earned her the nickname “Queen of the Ooze”

Author, Endosymbiosis theory of cell evolution

Bacteria: heavy lifters of Gaia

Margulis showed that bacteria and algae are the prime movers of the biological processes that keep Earth’s atmosphere far from equilibrium and favorable to life.

Bacteria are also involved in the possible negative feedback loops for temperature regulation

What is Gaia?

GAIA (if it exists!) is a collection of negative feedback loops

These loops stabilize the Earth’s physical environment

The physical environment is maintained in a condition favorable to life.

Problem with the Gaia theory

Gaia theory seems to require cooperation among organisms to stabilize Earth physical conditions

Conscious cooperation would involve mysticism

Unconscious cooperation could not have evolved

Lovelock’s response: Daisyworld

Daisyworld is a computer simulation of a hypothetical world inhabited by patches of black and white daisies

Its purpose is to show that organisms can unconsciously cooperate to regulate temperature

No mystical cooperation is needed!

Daisyworld

Both black and white daisies grow best at 22.5° CAir is slightly warmer over black daisy patchesAir is slightly cooler over white daisy patches

Inside the Daisyworld Model1. Incoming solar and

albedo determine absorbed solar

2. Use zero-D energy balance model to determine planetary temperature

3. Calculate daisy growth rates

4. Recalculate planetary albedo (feedback loop)

Daisyworld simulation

First, run the model long enough for Daisyworld temperature to reach equilibrium

Then, apply a sudden change in solar input

Observe how Daisyworld reacts to restore its temperature

When Daisyworld is cool…

Air temperature over the black patches is higher

Black patches grow more

Overall planet color becomes darker

Planet albedo decreases

When Daisyworld is cool…

Planet absorbs more sunlight and gets warmer

Daisies have altered the climate!

Daisyworld temperature is closer to optimal temperature for daisies!

When Daisyworld is warm…

Air temperature over the black patches is higher

White patches grow more

Overall planet color becomes lighter

Planet albedo increases

When Daisyworld is warm…

Planet absorbs less sunlight and gets cooler

Daisies have altered the climate!

Daisyworld temperature is closer to optimal temperature for daisies

Daisies have created a negative feedback loop! This process is what might have created GAIA.

A religious movement adopts a computer model…

Neo-pagan religious movement grew out of dissatisfaction with existing ideas of GodFeminist critique: male God encouraged patriarchal societyEnvironmentalist critique: human domination is destructive to EarthIs GAIA another name for Mother Earth?Biocentric philosophical viewpoint