Greenhouse Gases and Their Impact on Climate

Composition of the Atmosphere

• The atmosphere contains various gases, including greenhouse gases such as:
  • Carbon dioxide (CO2)
  • Methane (CH4)

Properties of Greenhouse Gases

• These gases have the ability to retain heat, warming the atmosphere.
• Key role in maintaining Earth's temperature:
  • Allow life to flourish by keeping the planet warm.

Process of Heat Retention

• The sun produces light made of photons.
  • Photons pass through the atmosphere and hit the Earth's surface.
• Light-colored surfaces (ice/snow) reflect photons back into space.
• Darker surfaces (forests/oceans) absorb photons, converting some energy into heat (infrared radiation).
  • Analogy: Dark clothing absorbs sunlight and produces heat.
• Heat radiates from the surface back into the atmosphere.
• Most heat escapes to space, but some interact with greenhouse gases.
  • Gases absorb the infrared energy and release it slowly back into the atmosphere.

Importance of Greenhouse Gases

• Essential in keeping Earth's temperature within life-sustaining limits.
• Needed in small concentrations (parts per million).
• Lesser greenhouse gases would result in frozen water.

Human Impact on Greenhouse Gas Levels

• Human activities increase greenhouse gas concentrations:
  • Burning fossil fuels
  • Agricultural practices
• Notable increase in CO2 levels:
  • Over 400 parts per million presently.
  • Greater than 20% increase since the 1960s.

Consequences of Increased Greenhouse Gases

• Rise in global temperatures, known as global warming.
• Changes in regional climates, referred to as climate change.
  • Documented cases of altered weather patterns, including severe storms and droughts.
• Projected increase in average global temperature by 3.6°F by 2100.