Earth as a SystemEarth as a Systemand The Gaia and The Gaia HypothesisHypothesis

Earth as a SystemEarth as a SystemEarth is often described as a large system Earth is often described as a large system of interacting parts and cycles.of interacting parts and cycles.A system can be defined as a set of parts A system can be defined as a set of parts that work together. Systems can either be that work together. Systems can either be open or closed.open or closed.In an open system, parts can be either lost In an open system, parts can be either lost from or added to the system.from or added to the system.In a closed system, all the parts exist in In a closed system, all the parts exist in precise amounts, and nothing can be lost precise amounts, and nothing can be lost or added.or added.

Earth as a SystemEarth as a SystemBoth kinds of systems, open and closed, Both kinds of systems, open and closed, need a source of energy to drive them.need a source of energy to drive them.Earth functions as a closed system.Earth functions as a closed system.All the important ingredients of water, All the important ingredients of water, gases, and chemical nutrients exist on gases, and chemical nutrients exist on Earth in limited amounts.Earth in limited amounts.In order for life on Earth to continue to In order for life on Earth to continue to function, these ingredients have to be function, these ingredients have to be recycled over and over again.recycled over and over again.The driving force behind all these cycles is The driving force behind all these cycles is the sun.the sun.

Earth as a SystemEarth as a SystemIt is important that we are aware of our It is important that we are aware of our planet’s status as a closed system.planet’s status as a closed system.If we use up or seriously deplete any If we use up or seriously deplete any of Earth’s essential ingredients, or if of Earth’s essential ingredients, or if we disrupt its natural cycles, we risk we disrupt its natural cycles, we risk upsetting the balance of the entire upsetting the balance of the entire system.system.

The Gaia HypothesisThe Gaia HypothesisThis controversial idea about Earth and its This controversial idea about Earth and its complex workings was developed by complex workings was developed by British biochemist James Lovelock in British biochemist James Lovelock in 1972.1972.The central theme of the hypothesis is that The central theme of the hypothesis is that Earth is viewed as a Earth is viewed as a single living single living organismorganism..In the 4.6 billion years of its existence, the In the 4.6 billion years of its existence, the hypothesis states that Earth has hypothesis states that Earth has developed into a self-evolving, self-developed into a self-evolving, self-regulating and self-sustaining system.regulating and self-sustaining system.

The Gaia HypothesisThe Gaia HypothesisLovelock calls this living body Lovelock calls this living body GaiaGaia after the after the ancient Greek Earth goddess.ancient Greek Earth goddess.Gaia should be considered as including all the Gaia should be considered as including all the processes that operate in, on, and around Earth.processes that operate in, on, and around Earth.The planet Earth is the heart of an The planet Earth is the heart of an interconnected and unified living system that interconnected and unified living system that regulates its own environment so that it can regulates its own environment so that it can continue to thrive and to sustain itself in a continue to thrive and to sustain itself in a healthy manner.healthy manner.

The Gaia HypothesisThe Gaia Hypothesis

In Lovelock’s view, all life forms on In Lovelock’s view, all life forms on Earth, from the simplest to the most Earth, from the simplest to the most complex, interact and contribute to complex, interact and contribute to Earth in such a way as to produce Earth in such a way as to produce the best environment not only for the best environment not only for their own well-being, but also for their own well-being, but also for Earth as a whole in general.Earth as a whole in general.

The Gaia HypothesisThe Gaia HypothesisGaia makes constant adjustments Gaia makes constant adjustments and interventions to ensure the and interventions to ensure the Earth’s survival.Earth’s survival.Two of the most common ways for Two of the most common ways for Gaia to do this are by allowing Gaia to do this are by allowing species to evolve over time to meet species to evolve over time to meet new environmental challenges and by new environmental challenges and by ensuring that there is great diversity ensuring that there is great diversity of life forms on Earth.of life forms on Earth.

The Gaia HypothesisThe Gaia HypothesisLovelock points out that Gaia has been so Lovelock points out that Gaia has been so adaptable that she has been able to adjust adaptable that she has been able to adjust even after catastrophic events like asteroid even after catastrophic events like asteroid collisions. collisions. For this reason he believes it is unlikely For this reason he believes it is unlikely that Gaia could be truly endangered by the that Gaia could be truly endangered by the relatively recent and short-term assaults of relatively recent and short-term assaults of humankind.humankind.Instead, he thinks the real danger for Instead, he thinks the real danger for human beings may be in the way Gaia human beings may be in the way Gaia reacts to their environmental assaults.reacts to their environmental assaults.

The Gaia HypothesisThe Gaia HypothesisLovelock’s ideas have been accepted by Lovelock’s ideas have been accepted by many scientists who argue that the Gaia many scientists who argue that the Gaia hypothesis offers the best way of hypothesis offers the best way of examining and understanding the complex examining and understanding the complex chemical, biological, and physical chemical, biological, and physical processes that operate on Earth and that processes that operate on Earth and that ensure the continuation of life.ensure the continuation of life.However, critics argue that life adapted to However, critics argue that life adapted to planetary conditions and evolved in planetary conditions and evolved in separate ways.separate ways.