Earth as a System and The Gaia Hypothesis

1. Earth as a Systemand The Gaia Hypothesis

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

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

4. Earth as a System • It is important that we are aware of our planet’s status as a closed system. • 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.

5. The Gaia Hypothesis • This controversial idea about Earth and its complex workings was developed by British biochemist James Lovelock in 1972. • The central theme of the hypothesis is that Earth is viewed as a single living organism. • In the 4.6 billion years of its existence, the hypothesis states that Earth has developed into a self-evolving, self-regulating and self-sustaining system.

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

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

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

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

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