Visible light from sun passes through glass in greenhouse Glass is semi-transparent to infrared radiation Trapped IR waves (heat waves) – warm up greenhouse Visible light is absorbed by surface (ground) Light is re-radiated as heat (infrared)

Different gases, different impacts Influence due to: Ability to absorb long-wave radiation (heat) Concentration of gas in atmosphere Methane: Warming Potential: High Duration: Short – 12 yrs Increase: 150% Concentration: 1700 p.p.b. Carbon Dioxide: Warming Potential: Good Duration: Long– 50-200 yrs Increase: 40% Concentration: 400 p.p.m. Nitrous Oxide: Warming Potential: Great Duration: Long– 114 yrs Concentration: 320 p.p.b. Water Vapor: Warming Potential: Fair Duration: 9 days Concentration: variable

Low Albedo Effect High Albedo Effect Low absorption is due to reflective surfaces – cooler atmosphere High absorption, less reflective surfaces - warmer atmosphere

Effect of angle of the sun? Types and amounts of gases in atmosphere?

Due to atmosphere being opaque to more harmful, high energy waves  protective barrier Prevents overwarming IR is absorbed by atmosphere  leads to warming

Climate – patterns in temperature/precipitation Change – thousands of years Contributions to Change: Volcanic activity Quantity of solar radiation Position of continents Oscillations in ocean currents Fluctuations in Earth’s orbit Inclination of Earth’s axis Equipment was introduced within last couple hundred years Majority of data comes from proxy Tree rings, coral reef growth, ice cores, pollen type, fossil type Correlation: Temperature increases first, followed by CO2 concentration Positive feedback mechanism

Industrial Revolution Muscle power  fuel (fossilized organic matter) power Releases GHGs into atmosphere CO2 increased 35% Concentrations of GHGs naturally low  prevents too much warming CO2 emissions: Human transport, deforestation, heating homes, high meat diet, purchasing high mileage goods Methane emissions: Cattle Nitrous oxide emissions: catalytic converters in cars, fertilizers, industrial processes

Threats to Coral Reefs Death of coral = bleaching Sensitive to: Water temperature Water acidity Depth of water

Challenges from Critics Distinguish between politically controversial and scientifically controversial