Study Notes on Greenhouse Effect and Climate Change

The uneven heating of the Earth causes significant phenomena.
- Key effects include the movement of air currents (wind) and rainfall patterns.
Heat Dynamics
- Heat absorbed by Earth and its objects during the day is lost by radiation at night.
- A portion of this heat energy is trapped by a “blanket” made mainly of carbon dioxide and water vapor, leading to the greenhouse effect.

Definition: The greenhouse effect is a phenomenon where sunlight warms the Earth, but heat cannot escape due to a denser atmosphere.
Historical Context: The greenhouse effect has existed since the early times, maintaining an Earth temperature that supports life.
Current Issues: Human activities are increasing carbon dioxide in the atmosphere, exacerbating the greenhouse effect and global warming.
- Main Greenhouse Gases: Carbon dioxide (CO₂), methane (CH₄), and water vapor (H₂O).
- Rising temperatures lead to melting of the Antarctic ice sheets, receding ice in Greenland, and rising sea levels by about 1-5 cm annually.
Specific Example: Mount Kilimanjaro has lost approximately 80% of its ice cover since the early 20th century.

In August 2018, a study predicted that if the average global temperature rises more than 1.5 °C to 2 °C, the Earth could enter a “Greenhouse Earth” phase.
- Findings from "Trajectories of the Earth System in the Anthropocene" published in the Proceedings of the National Academy of Sciences indicate potential average temperature rises of 4 °C to 5 °C.
- Consequence of this phase includes rising sea levels by up to 60 m due to ice cap and glacier melting.
- Urgent call for policymakers to transition to a "carbon neutral economy".

Observable changes: Europe has seen intense heat waves, floods, and fires, even in regions like Sweden.
- Australia is experiencing one of the worst droughts in human history.
- South Africa also faces severe droughts and shifting weather patterns.
- Notable events include the summer of 2018, marked by extreme wildfires in California and Greece.
Triggers of Climate Change
- Factors influencing global temperatures include:
- Release of methane from icy soils in the Arctic and seabeds.
- Unlike current conditions where the sea absorbs carbon dioxide, these changes will lead to increased emissions.
- The Amazon forests and Antarctic ice are critical for climate regulation.

Wind is caused by moving air resulting from high and low-pressure systems in the atmosphere.
- Wind influences the transpiration rate of plants.
Rainfall Mechanisms
- Cooler air is denser than warmer air; therefore, warm air ascends while cooler air descends.
- As warm air rises, pressure decreases, causing it to expand and cool.
- Cooling air leads to moisture loss in the form of rain or snow.
Historical Context of Greenhouse Gases
- Increase in greenhouse gases began in the early 1800s, primarily due to the Industrial Revolution.
- This created an imbalance in Earth systems, resulting in climate changes.
Additional Influences on Rainfall
- Local physiographic factors such as altitude and global positioning influence rainfall patterns.
- Examples of physiographic factors include gradient (slope), rain-shadow, and height above sea level.

Urgent Actions Recommended:
- Reforestation initiatives (not plantation forests).
- Proper management of agricultural land.
- Protection of biodiversity.
- Development of technologies to extricate carbon dioxide from the atmosphere.

The atmosphere consists of a mixture of gases, dust, and solid particles held by Earth’s gravity.
- The atmosphere reflects 29% of the sun's radiation back into space and absorbs about 20%, allowing 51% to reach the Earth’s surface.
- Most incoming energy is reflected as heat, accounting for Earth’s warming during the day and cooling at night.

Composition of atmosphere:
- Approximately 79% nitrogen (N)
- Almost 21% oxygen (O₂)
- Only 0.04% carbon dioxide (CO₂)
Variability: Percentages of water vapor, dust, and solid particles can differ regionally.

Several human activities are responsible for the increase of carbon dioxide:
1. Increased human population exhaling CO₂.
2. More motor vehicles releasing CO₂.
3. Increased industrial activities burning coal for energy.
4. Deforestation leading to fewer plants available to perform photosynthesis.

Climate change is evidenced by abnormal droughts, floods, and severe winters worldwide.

Temperature is a key determining factor for climate, influencing the adaptations of plants and animals.
There is a direct correlation between temperature and light intensity: the brighter the sun, the higher the temperature, and vice versa.

Worcester experiences lower annual rainfall than Paarl, located only 50 km away, due to its position in the rain-shadow of the Boland mountains.
- The Paarl region has Fynbos vegetation, while Worcester displays typical Klein Karoo succulent vegetation.

Animals adopt various strategies based on temperature:
- Nocturnal behavior in smaller prey animals like mice leads to adaptations in predatory behaviors in animals such as owls and cats.
- Estivation is a protective strategy during extreme heat (common in smaller invertebrates like snails).
- Hibernation is a survival strategy during cold weather, utilized by mammals (e.g., bears) and certain reptiles.

Soil is pivotal for various organisms, providing the medium for plant growth and nutrient replenishment.

Soil also hosts diverse organisms such as earthworms, insects, moles, bacteria, etc.
- These organisms play critical roles in soil health and sustainability.