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Earth Systems Science or Gaia. A new/different kind of ecology.
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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
“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?
The origins Of Gaia Theory
Daisy World Simulation • http://library.thinkquest.org/C003763/flash/gaia1.htm
Daisy World The evolution of climate on DaisyworldThe 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
