The Gaia Hypothesis & The Earth As A System

An introduction to John Lovelock's Gaia Hypothesis and the concept of planet Earth as a closed system.

1. The Gaia Hypothesis
&
The Earth As A System
Global Geography 12,
CP Allen High School

2. What is Gaia?
Greek mythology – goddess of the earth
mother of living things, sustainer of life

3. Hypothesis=?
thesis= main idea or argument
(like in an essay or debate)
hypothesis= a theory or proposal based on
scientific or logical reason

4. Gaia Hypothesis
An idea proposed by James Lovelock (published
in 1979)
All living things on earth (biosphere) function as
one SUPERorganism that changes its
environment to create conditions that best
meet its needs, with the ability to self-regulate
critical systems needed to sustain life

5. 4 Systems
The 4 systems that sustain life are:
Biosphere (living things)
Hydrosphere (all water on earth’s surface)
Atmosphere (air)
Lithosphere (soil)

6. Self-Regulation
Surface Temperature
maintenance of a consistent temperature that
supports life
Atmospheric Composition
the composition of the air remains the same, even
though it should change a lot over time
Ocean Salinity
the ocean never gets more/less salty, even though
minerals are forever being added from rivers

7. What is a System?
System?
A group of parts that function together
Open v. Closed
all systems require an energy source to drive them
parts can be
either lost from or
added to the
system
all parts exist in
precise amounts,
and nothing can
be lost or added.

8. System Earth
•Earth=closed system.
•All ingredients (water, gases, and chemical
nutrients) exist on Earth in limited amounts.
•For life on Earth to continue to function, these
ingredients have to be recycled over and over
again.
< linear closed loop>
•Energy source: the sun

9. SYSTEM WARNING
•If we use up or seriously deplete any of Earth’s
essential ingredients, or if we disrupt its natural
cycles, we risk upsetting the balance of the entire
system.

10. To sum up…
•Earth = single living organism.
•Over 4.6 billion years the Earth has become:
self-evolving self-regulating self-sustaining
Evolve: change and become more effective
Regulate: able to monitor/control/adjust itself
Sustain: to maintain current life indefinitely

11. Furthermore…
•All living things work act to create environmental
changes that benefit all life forms
•The Earth is always changing and adapting in
response to its lifeforms

12. Gaia in action
•Planetary simulation: Daisyworld
http://library.thinkquest.org/C003763/flash/gaia1.htm