Solar System, Earth Systems, and Natural Resources
The Solar System and Earth
The solar system consists of eight planets: four small, inner planets (Mercury, Venus, Earth, and Mars) and four major, outer planets (Jupiter, Saturn, Uranus, and Neptune). There are also 152 natural satellites (moons) within the solar system.
Earth: A Unique Planet
Earth is distinct from other planets due to several key factors:
- Its average distance from the sun.
- An atmosphere that generates a greenhouse effect, resulting in an average temperature of 15°C.
- Abundant water, especially in liquid form on its surface.
- A vast diversity of life forms.
Systems and Causal Relations
System Types
A system is a set of interrelated elements. There are two primary types of systems:
- Open System: Allows for the input and output of both matter and energy.
- Closed System: Allows for the input and output of energy, but not matter.
Causal Relationships
A variable is a measurable aspect of a system. Causal relations describe the cause-and-effect relationships between variables within a system. Variable types include:
- Simple: Involve relationships between two variables. These can be:
- Positive (directly proportional): + = +, – = –
- Negative (inversely proportional)
- Chained: + (-) = -, – (-) = +, + (+) = +
- Composed: Occur when two or more variables are related in a closed sequence. These create feedback loops:
- Positive Feedback Loops: Variables grow or diminish uncontrollably, unless limited by other factors.
- Negative Feedback Loops: Variables are self-regulating. These occur when the sum of the signs in the loop is negative.
Earth as a System
Earth functions as a complex system with intimately related components:
- Geosphere: The solid Earth, including rocks and minerals.
- Edaphosphere: Encompasses soils worldwide, representing an intersection between the geosphere and biosphere.
- Biosphere: All living organisms on Earth, from birds to bacteria in the deepest abyssal plains.
- Atmosphere: The gaseous envelope surrounding Earth; its upper limit is poorly defined. It controls external geodynamics and weather, influencing the edaphosphere and living organisms.
- Hydrosphere: All water on Earth’s surface, including the cryosphere (ice).
Natural Resources and Human History
From the Stone Age, humanity depended entirely on nature. The Bronze and Iron Ages saw the development of tools, leading to human expansion and improved living standards. The Industrial Revolution, marked by James Watt’s steam engine in 1769 (fueled by coal), initiated the widespread exploitation of fossil fuels.
Resources
A resource is a natural asset with potential human use. Resources are categorized as:
- Renewable: Infinite or replenished faster than demand.
- Non-renewable: Replenished slower than demand.
Resources can also be classified by their use:
- Energetic: Used for their energy content.
- Non-energetic: Used for other properties (e.g., fishing, timber, minerals, grasslands, water).
Natural Hazards and Environmental Impact
A natural hazard is an environmental risk caused by interactions between natural processes and humans, their property, or resources.
An environmental impact is any consequence of human actions on the environment.