The GAIA Hypothesis and it s role in Earth

The GAIA Hypothesis and it‘s role in Earth System Modelling Quelle: Wikipedia The release of this image had an effect in leading to the proposition that the Earth is alive. GCM – 1. Semester: Physical Fundamentals of GC, Juliane Gnau

The GAIA Hypothesis and it‘s role in Earth System Modelling Content • Earth System Science • Earth System Modelling • The GAIA Hypothesis • Recent research • “Official proof of acceptance”

Earth System Science • … treats the entire Earth as a system • this system evolves as a result of positive and negative feedbacks between many different systems • gives scientists the ability to explain the past and possible future behaviour of the Earth system ms: See the comlete version of the so-called Bretherton Diagram (Francis P. Bretherton, 1986)

What is Earth System Modelling? Gaia theories explain the behaviour of the Earth system in terms of the influence of the biosphere Quelle: Max-Planck-Institut Interacting components on the environment are modeled in unison to understand how feedbacks between the components influence the properties of the whole system.

ms: That is only half the truth. It shows only the natural systems approach to climate modelling. The whole Earth System Modelling would comprise the socio-economic modelling as well, like: world economic system, national and international institutions and actors, …. Quelle: Max-Planck-Institut, verändert Development of Earth System Modelling

Goals of Earth System Modelling • to predict the future of the planet Earth • instrument to take appropriate actions in the future within the framework of future management of the Earth

The GAIA Hypothesis James Lovelock‘s definition: a complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet

The Initial Hypothesis • biomass modifies conditions on planet • hospitality = homeostasis • homeostatic feedback system operated by the biota leads to stabilization of global temperature and chemical composition Global control system: • surface temperature • atmospheric composition • ocean salinity

The Development of the Hypothesis • 1960: Ecological theory: the Earth as an organism • Core assumption of hypothesis: „Lives of a cell“ • Scientifically formulated by J. Lovelock • Supported by scientific experiments + providing useful predictions Theory • 1972: "Gaia as seen through the atmosphere" • Until 1975 almost totally ignored • 1979: book “Gaia: A new look at life on Earth”

History The Development of the Hypothesis • Acception took many years • 1980’s: still confusion what the GAIA theory really is • Criticism: 1. view is too theological 2. lack of scientific evidence 3. GAIA is not a living organism

History The Development of the Hypothesis • response to criticism = math. Daisyworld proof for existance of feedback mechanisms • Lovelock‘s reframing as geophysiology • growing acceptance of Earth System Science • silenced many critics

Recent developments • Gaia Theory has developed considerably • 1998 book: “The Symbiotic Planet”(L. Margulis) "Gaia is not an organism", but "an emergent property of interaction among organisms". New definition: “…the series of interacting ecosystems that compose a single huge ecosystem at the Earth's surface. “ • both theories are valid today

Recent developments The GAIA Hypothesis • two GAIA Conferences 1. 1988: the Gaian teological views or "types" of Gaia Theory 2. 2000: specific mechanisms: • has Gaia changed in time? • how can the feedbacks influence the climate? • how can mechanisms be modeled?

Today The GAIA Hypothesis - Summary • the Gaia hypothesis is modified • biosphere = ecosystem • the Gaia hypothesis is consistent with a modern vision of global ecology, relaying on the concepts of common usage, use the biosphere and biodiversity ms: Intheory to signify apeople often an opinion, word conjecture, • not a theory anymore (? ) or a speculation. In science however, a theory is a proposed description, explanation, or model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations! • part of Earth System Science • scientific model in geo-biosphere • non-scientists: self-regulating Earth

More recent research The GAIA Hypothesis • modelling real biochemical cycles of Earth Daisyworld-like regulation • today: simple feedback mechanisms accepted carbon dioxide • more difficult homeostatic mechanisms ? planetary albedo

More recent research “Official proof of acceptance“ • Amsterdam declaration of the scientific communities of 4 international global change research programmes: • threat of significant climate change • increasing human modification of global environment findings and statements seem to be fully consistent with the Gaia theory The Earth System behaves as a single, self-regulating system comprised of physical, chemical, biological and human components.

More recent research “Official proof of acceptance“ “The interactions and feedbacks between the component parts are complex and exhibit multi-scale temporal and spatial variability. ” “Global change cannot be understood in terms of a simple cause-effect paradigm. Human-driven changes cause multiple effects that cascade through the Earth System in complex ways. ” “These effects interact with each other and with local- and regional-scale changes in multidimensional patterns that are difficult to understand even more difficult to predict. ”

The GAIA Hypothesis and it‘s role in Earth System Modelling Thank you for listening ms: Richard Mabey reviews The revenge of Gaia by James Lovelock: “After Hurricane Katrina, a black Gaian joke went the rounds, couched in White House newspeak: Successful mission against the Gulf of Mexico oilfields. Some collateral damage in New Orleans. ” Sources: • Wikipedia • Max-Planck-Institut • http: //serc. carleton. edu/introgeo/earthsystem/nutshell/index. html

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