Understanding Earth's Atmosphere and Climate Change

Composition of Earth's Atmosphere

• Nitrogen (78%)
• Oxygen (20%)
• Argon (1%)

Greenhouse Gases

Examples: H2O, CO2, CH4, NO2, O3

Importance: Without greenhouse gases, Earth's temperature would be -22 to -36 degrees Celsius.

Greenhouse Effect

Solar energy absorbed by Earth and re-radiated as heat by greenhouse gases.

1. Natural Greenhouse Effect
2. Human-Induced Greenhouse Effect (Global Warming)

Global Warming / Climate Change

Caused by burning fossil fuels, deforestation, and human activities that increase carbon dioxide levels, leading to Earth's warming.

Ozone, Hole in Ozone, UV Rays, CFCs

Ozone

Located mostly in the lower stratosphere, it acts as a shield against harmful UV radiation from the sun.

Hole in the Ozone Layer

Causes: Primarily caused by human-made chemicals like chlorofluorocarbons (CFCs).

Effects:

• Increased risk of skin cancer and cataracts
• Suppression of the immune system
• Damage to plant life

UV Rays

Harmful Effects: Similar to those caused by the hole in the ozone layer.

Carbon Cycle

Earth's natural process of maintaining the balance of carbon dioxide (CO2) in the atmosphere.

Key Processes:

• Plants release oxygen (O2) through photosynthesis.
• Animals and volcanoes release carbon dioxide (CO2).
• Fossil fuels release CO2 when burned.

Carbon Storage

Besides the atmosphere, carbon is stored in:

• Oceans
• Underground (rocks and sediments)
• Living organisms

Albedo

The measure of how much solar radiation is reflected back into space by a surface.

Examples:

• Ice and snow have high albedo (reflect more).
• Dark surfaces like asphalt have low albedo (absorb more).

Clouds & Albedo

Clouds play a complex role in albedo and the greenhouse effect:

• Warmer temperatures lead to more evaporation and cloud formation.
• White clouds have high albedo and reflect sunlight.
• Water vapor in clouds is a greenhouse gas, trapping heat.

Air Circulation: Convection, Coriolis Force

Convection:

• Warm air rises (less dense).
• Cold air sinks (denser).

Coriolis Force:

• Earth's rotation deflects wind patterns.
• Creates circular wind patterns like Hadley cells.

Hadley Cell

A large-scale atmospheric circulation pattern that influences global weather patterns.

Hurricanes/Cyclones/Typhoons

Rotating storm systems with different names depending on their location:

• Hurricanes: Atlantic and Eastern Pacific
• Typhoons: Western Pacific and Indian Ocean
• Cyclones: General term

Monsoons

Seasonal wind patterns that bring heavy rainfall to certain regions.

Ocean Currents

Surface Currents: Driven by wind.

Deep Ocean Currents: Driven by differences in temperature and salinity (Global Conveyor Belt).

Ocean Gyres / Ocean Garbage Patches

Large circular ocean currents (gyres) trap plastic debris, forming garbage patches.

Plastics & Microplastics

Plastic pollution breaks down into tiny microplastics, posing environmental threats.

Deep Ocean Currents & Carbon Storage

Cold, deep ocean waters store large amounts of carbon dioxide.

Milankovitch Cycles

Changes in Earth's orbit and rotation over long periods influence climate:

• Obliquity (tilt)
• Eccentricity (orbit shape)
• Precession (wobble)

Ice Cores & Past Climate

Ice cores from Antarctica and Greenland provide valuable data on past climate conditions.

Relationship between CO2 and Temperature

Higher CO2 levels are associated with higher temperatures, as shown in ice core data.

Current CO2 Levels

Atmospheric CO2 levels are currently at their highest in at least 800,000 years.

Fossil Fuel Burning & CO2

Burning fossil fuels releases CO2, contributing to climate change.

Deforestation & Climate Change

Deforestation reduces the Earth's ability to absorb CO2, exacerbating climate change.

Livestock & Climate Change

Livestock, particularly cattle, emit methane (CH4), a potent greenhouse gas.

Agriculture & Climate Change

Agricultural practices, such as fertilizer production, contribute to greenhouse gas emissions.