3. Greenhouse Effect D4.3
Page 1: Introduction to Climate Change
Topic: Drivers of Climate Change
Page 2: Composition of Earth's Atmosphere
Major Gases:
Argon: 0.93%
Carbon Dioxide (CO2): 0.04%
Oxygen (O2): 21%
Nitrogen (N2): 78%
Page 3: Electromagnetic Radiation
Nature of Electromagnetic Radiation:
Travels in waves.
Includes a broad spectrum from long radio waves to short gamma rays.
Page 4: Sunlight and the Greenhouse Effect
Emission of Light from the Sun:
Various types with different wavelengths.
Some light reaches Earth's surface; some absorbed by atmospheric gases.
Page 5: Overview of Incoming Solar Radiation
Key Point:
Emission and effect of sunlight categorized; features of the greenhouse effect discussed.
Page 6: Effects of UV Light
UV Absorption by Ozone:
Ozone layer absorbs most UV radiation, protecting Earth from sunburn effects.
Page 7: Solar Radiation Breakdown
Incoming Radiation Composition:
52-55% Infrared (above 700 nm)
42-43% Visible light (400-700 nm)
3-5% Ultraviolet (below 400 nm)
Page 8: Shortwave vs Longwave Radiation
Definitions:
Shortwave Radiation:
Emitted from the sun; peaks at 400 nm.
Longwave Radiation:
Emitted from Earth; peaks at 10,000 nm (infrared).
Page 9: Understanding the Greenhouse Effect
Definition:
Process of radiation from a planet's atmosphere warming its surface above natural temperatures.
Page 10: Shortwave Blockage
Ozone's Role:
25% of the sun's shortwave radiation, mainly UV, blocked by ozone before reaching Earth.
Page 11: Shortwave Transmission
Transmission of Radiation:
75% of shortwave radiation reaches Earth's surface.
Page 12: Absorption and Emission
Earth's Radiation Activity:
Absorbs shortwave radiation, re-emits as longwave radiation (heat).
Page 13: Greenhouse Gas Absorption
Longwave Radiation Capture:
Up to 85% of re-emitted longwave radiation captured by greenhouse gases.
Page 14: Heat Return to Earth
Warming Effect:
Longwave radiation returned to Earth contributes to warming.
Page 15: Natural Greenhouse Effect
Importance:
Natural process keeping Earth at an average temperature of 15°C; without it, -18°C.
Reduces temperature variation day and night.
Page 16: Summary of Greenhouse Effect
Key Points:
Sun emits a range of wavelengths.
Earth absorbs and re-emits shortwave radiation as longwave.
Greenhouse gases (H2O, CO2, CH4, NOx) play a key role.
Page 17: Enhanced Greenhouse Effect
Definition:
Additional heat retained due to increased greenhouse gases from human activities since the industrial revolution.
Page 18: Impact of Human Activity
Understanding Enhancement:
Natural greenhouse effect versus additional CO2 trapping from human actions.
Page 19: CO2 Measurements
Demonstration Setup:
Visual measurements of temperature differences with and without CO2.
Page 20: Natural CO2 Sources
Origin of CO2:
Produced by:
Cellular respiration
Decomposing biomass
Volcanic eruptions
Natural wildfires.
Removed by:
Photosynthesis
Ocean absorption.
Page 21: Current CO2 Levels
Present vs Historical Levels:
Today: 426 ppm
Historical peak: 300 ppm.
Page 22: Vostok Ice Core Data
Analysis Findings:
Strong correlation between CO2 and temperature; high CO2 correlates with warm ages.
Page 23: Ice Core Evidence
Utilization of Ice Cores:
CO2 levels and temperatures deduced from trapped gas bubbles over 420,000 years.
Page 24: Historical Analysis of CO2
Long-term Trends:
Historical data shows fluctuating CO2 correlated with warm and ice age cycles; current CO2 is unprecedented over the last 400,000 years.
Page 25: Significant Greenhouse Gases
Major Greenhouse Gases:
Carbon Dioxide (CO2) and Methane (CH4).
Non-greenhouse gases (e.g. N2, O2) do not absorb longwave radiation.
Page 26: Observing Atmospheric CO2 Changes
Activity Overview:
Monthly CO2 variations observed from 1959-60, with graphical data provided for analysis.
Page 27: Sources of Enhanced CO2
Human Contributions:
Fossil fuel combustion in engines, biomass burning, deforestation contribute to increased CO2.
Page 28: Methane Emission Sources
Sources of CH4:
Methanogenic bacteria in ruminants, melting permafrost, landfills, and swamp decay.
Page 29: Water Cycle and Heat Content
Impact of Greenhouse Gases:
Increased heat content accelerates the water cycle.
Page 30: Climate Feedback Loops
Feedback Definitions:
Positive Feedback: Amplifies processes (e.g., global heating).
Negative Feedback: Rare; reduces the created process.
Page 31: Melting Ice as Positive Feedback
Example of Feedback:
Melting ice enhances warming by reducing albedo effect.
Page 32: Permafrost and Methane Feedback
Impact of Permafrost:
Melting releases methane, further accelerating global warming.
Page 33: Methane Emissions Impact
Greenhouse Warming:
Ongoing emissions from land and ocean impact atmosphere and climate.
Page 34: Ocean's Role in Climate
Ocean Absorption:
Oceans absorb CO2, but warming may reduce this ability.
Page 35: Droughts and Wildfires
Consequences of Increased Warming:
Leads to more frequent droughts and wildfires, further impacting climate.
Page 36: Tipping Points and Ecosystems
Ecosystem Resilience:
Changes can overwhelm systems, leading to a tipping point.
Page 37: Boreal Forest Changes
Carbon Sink Role:
Boreal forests act as carbon sinks; climate change may convert them to sources.
Page 38: Impact of Droughts and Fires
Destruction of Carbon Storage:
Increased forest fires release stored CO2, hindering carbon capture.
Page 39: Assignments
Tipping Points Assignment:
Explore changes in boreal forest carbon cycles, melting ice impacts, and habitat loss in polar regions.