Lecture 9 - A Habitable Planet Flashcards
What is Gaia Theory?
The Earth’s biota and surface environment form a self-regulating system that keeps the planet in a habitable state.
What are two types of feedback?
Active feedback such as in the geophysiological model.
Passive feedback such as in the biogeochemical model.
What is Daisyworld?
A parable world, invented to demonstrate that self-regulation can occur without foresights or planning.
What type of systems are Venus and Mars?
Geochemical systems.
What type of system is Earth?
Biogeochemical systems.
Why is Earth a biogeochemical system?
Rock weathering and transporting of materials to the oceans is driven by plant roots and microbial activity in soils.
Seawater composition is determined by biotic processes.
Trace gases in the atmosphere are derived from the biosphere.
What are human influences on the Earth?
Carbon extraction is 36 times faster than through natural processes alone.
Metallic element extraction and mobilisation is several fold faster than release by weathering.
Atmospheric composition is changing.
Growing population increases change and impact.
What does unsustainability cause?
Less biodiversity which results in a less productive ecosystem that destroys the Earth’s life support system.
What does sustainability rely on?
Recycling and re-use as the basis of a zero-emission society.
Eliminating pollution of the atmosphere, waters and land.
Managing soils.
What are the next steps for Earth?
Waste less
Capture, store and use the sun’s limitless energy to power our lives.
Cultural change - personal and corporate responsibility.
Reduce population growth.
What happens after exponential population growth?
A dramatic population collapse.
How far does the oxidising layer of Earth extend to?
A depth of a few kilometres
What is hydrothermal circulation at mid-ocean ridges responsible for?
Production of sulphide minerals.
Why does upwelling occur off the west coast of continental land masses?
Prevailing winds.
What is the temperature of the stratopause?
0 degrees Celsius.
