the gaia hypothesis: a new look at life on earth
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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