Environmental Systems and Impacts
Causal Relationships in Ecosystems
Causal systems involve interactions or causal relationships, which can be simple or complex.
Simple Causal Relationships
These involve a direct, unilateral influence of one variable on another.
- Direct: An increase or decrease in one variable causes the same change in another (e.g., increased atmospheric carbon dioxide leads to increased plant biomass).
- Inverse: An increase or decrease in one variable causes the opposite change in another (e.g., increased forest cover leads to reduced soil erosion).
More than two results can be direct or inverse (e.g., increased atmospheric carbon dioxide leads to increased average temperature, decreased polar ice, and rising sea levels).
Complex Causal Relationships
One variable affects others, and these variations, in turn, affect the first, forming a feedback loop. Feedback can be positive or negative.
- Positive: The effect of one variable causes a deviation in the same direction in another variable.
- Negative: Tends to control positive feedback loops, as these cannot be sustained indefinitely.
Use + or – symbols above the arrow connecting concepts to indicate the direction of change.
Types of Environmental Impacts
Impacts are categorized by origin and severity.
By Origin
- Occupation: Involves permanent facilities (e.g., a dam), usually irreversible.
- Media: Effects from human activities degrading ecosystems (e.g., highway construction).
- Emission: Release of contaminants (e.g., industrial effluents, fumes).
- Extraction: Exploitation of natural resources to exhaustion.
By Severity
- Mild: Reversible upon cessation of causes (e.g., point pollution by organic matter).
- Moderate: Small magnitude but significant long-term effects (e.g., industrial discharges into a lake).
- Severe: Large magnitude and significance, reversible only with corrective actions (e.g., greenhouse effect, oil spills).
- Critical: Irreversible, involving destruction of the affected area (e.g., dam construction, nuclear waste disposal).
Environmental Systems
The term “environment” is complex and subjective. Systems theories explain it as multidimensional systems of complex interrelationships in continual change (MAB, UNESCO).
Global Warming
A growing concern due to excessive release of carbon dioxide and other gases trapping heat, exacerbated by deforestation and fossil fuel burning.
Food Chain and Desertification
Organisms’ life cycles are potential food sources. Desertification degrades the first step of the food chain, affecting trophic levels (e.g., lack of leaves prevents caterpillars from eating, affecting robins).
Solar Energy
Obtained by capturing light and heat from the sun.
Biotic Agriculture
Develops intraspecific dynamics.
Acid Rain
Formed when moisture combines with nitrogen oxides and sulfur dioxide from factories and vehicles, creating sulfuric and nitric acids.
Eutrophication
Refers to nutrient enrichment in an ecosystem, particularly aquatic ecosystems, characterized by an abnormally high abundance of nutrients.
UNESCO’s Belgrade Charter (1975)
Organized by UNESCO, this seminar aimed to examine environmental education trends and formulate guidelines. The Belgrade Charter calls for a change in development priorities, emphasizing environmental commitment.