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Earth Systems Science or Gaia
A new/different kind of ecology
• Holistic science, is an approach to research that
emphasizes the study of complex systems. This
practice is in contrast to a purely analytic tradition
(sometimes called reductionism) which purports to
understand systems by dividing them into their
smallest possible or discernible elements and
understanding their elemental properties alone. The
holism/reductionism dichotomy is often evident in
conflicting interpretations of experimental findings
and in setting priorities for future research.
From wikipedia
James Lovelock
“Gaia is the name of the earth seen as a single
physiological system, an entity that is alive at least to
the extent that, like other living organisms, its
chemistry and temperature are self-regulated at a state
favourable for its inhabitants.”
- James Lovelock
Gaia –
Goddess of
The Earth
Gaia Hypothesis in Extreme Form
Mostly promoted by Lynne Margulis
Characteristics of Gaia
• Gaia is an evolving system, a system made up of
from all living things and their surface environment –
the oceans, atmosphere and crustal rocks
• Living things and their surface environment are
tightly coupled and cannot be separated
• Gaia is an “emergent domain” – a system that has
emerged from the reciprocal evolution of organisms
and their environment over the billions of years of
life on Earth. Self-regulation emerged as the system
evolved. There is no foresight, planning or design
involved in this system.
Differences between live and dead planet
• A dead planet would be expected to have an
atmospheric composition close to equilibrium – all
possible chemical reactions among gases would have
taken place – these reactions should occur fairly soon
after planet forms
• A live planet (one that contained life) would have a
very different atmosphere because living organisms
use air as a source of raw materials and as a
depository for their waste. Both of these uses would
cause the atmosphere of living planet to be far from
chemical equilibrium
Gases on
live vs.
dead planets Dead planets
should have
gases at chemical
equilibrium
Global climate change?
• A puzzle - the sun has increased its radiative
heat output by 25 percent over the last 3.8
billion years yet during that time the earth’s
temperature has remained in a range hospitable
for life – Lovelock wondered did the earth in
some way actively regulate its climate?
• What do we mean when we say something is
alive?
Long Term Climate Change?
The origins
Of Gaia
Theory
Coccolithophore and Coccolith bloom
Global Coccolith Blooms
Coccoliths, DMS and Climate
Ocean currents
Daisy World Simulation
• http://library.thinkquest.org/C003763/flash/
gaia1.htm
Daisy World
The evolution of climate on
Daisyworld
The dashed curve shows the rise of
temperature on the model planet
due to increasing stellar luminosity,
with no life present, and the solid
line shows how a constant
temperature is maintained with life
(in the form of dark and light
dasies) first warming, and then
cooling, the surface. Finally, when
the heat flux from the star becomes
so great that not even the white
daisies can keep the planet cool
enough for life, deserts spread from
the equator and finally the system
fails and Daisyworld dies.
Earth – Gaia has changed over
geologic time
• Hadean – 4.6 to 3.8 BYA – pre-Gaia – there
was no life – the earth was far more
radioactive than now, resulting in vigorous
volcanic activity with a high output of CO2 to
the atmosphere and rapid reactions of the rocks
with oceanic water to produce large amounts
of H2 gas
Earth – Gaia has changed over
geologic time
• Archean – 3.8 to 2.5 BYA – early bacterial life
forms evolved and Gaia was born – the
atmosphere was largely N2 gas with CO2 and
methane both present at 0.1 to 1 percent.
Oxygen was present as a trace gas, rapidly
used up by reducing compounds in the
Archean environment
Earth – Gaia has changed over
geologic time
• Proterozoic – 2.5 to 0.7 BYA – originated with
a switch from a reducing to an oxidizing
environment. Earth was still mainly populated
by bacteria. Prokaryotic bacteria eventually
joined by more complex eukaryotic cells and
oxygen levels increased dramatically
Earth – Gaia has changed over
geologic time
• Phanerozoic – 0.7 BYA to present
Multicellular plants and animals develop –
oxygen rises to 21 percent of atmosphere,
Carbon dioxide lowered to 0.03 percent which
compensated for sun’s increasing luminosity.
More living organisms storing more CO2 –
trees, etc. – and thus reducing CO2 in
atmosphere
The future – Earth Systems Science?
• Earth Systems engineering is essentially the
use of systems analysis methods in the
examination of environmental problems. When
analyzing complex environmental systems,
there are numerous data sets, stakeholders and
variables. It is therefore appropriate to
approach such problems with a systems
analysis method.
The future – Earth Systems Science?
• Earth Systems Environmental Management
views the earth as a human artifact. "In order
to maintain continued stability of both natural
and human systems, we need to develop the
ability to rationally design and manage
coupled human-natural systems in a highly
integrated and ethical fashion- an Earth
Systems Engineering and Management
(ESEM) capability" – Braden Allenby