Global Warming: Anthropogenic Effects

Systems and Loops

• A system: a group of independent parts working together as a whole (e.g. human body)

• Positive Feedback Loop: Part of a systems output is fed back to input and increases effects of interacting parts

Negative Feedback Loops

• Decrease the effects of interacting parts to maintain equilibrium. To prevent, slow or reverse changes. Keep Homeostatic levels.

Energy Transfer• Conduction

– Transfer of thermal energy between 2 objects– E.g. metal pot on stove transfers heat from element to water in pot

• Convection– Transfer of thermal energy by highly energized molecules moving

from one place to another. Fluid create currents– E.g. ocean currents, wind currents

• Radiation– Transfer of thermal energy from the sun to the earth.

Electromagnetic radiation can travel through the vacuum of space heating up our planet

Energy Transfer In Oceans

• Warmer surface water– Heated by radiation– Less dense because warmer water so stays at surface

until current takes it N then the air cools it and it sinks (convection)

– Moves quickly at surface• Cold dense deep water

– Moves slowly at bottom of ocean– Pushes warm water our of the way as it sinks– More salty and dense

Ocean currents: Conveyor belts of energy

Cycles of weather

• El Nino– Heavy rains– Warmer than normal– Warm air brought by

Jet streams across the Pacific

• La Nina– Dry, drought– Cooler than normal– Warm air & cool

moisture pushed away from North America

Periodic warming & cooling of a huge mass of sea water. Impacts weather in N. America.

El Nino & La Nina

Green House Gases

• 90% of atmosphere made of N2 and O2. They don’t absorb infrared radiation

• Water 1-4%• CO2 0.036%• Water Vapour

– Most abundant greenhouse gas– Not increasing in amount. Humans don’t

release more of it

CO2 and Methane• Carbon Dioxide

– Main source: Animal respiration– Main human sourcecombustion of fossil fuels and fires– Main sink is plants and photosynthesis– **Deforestation** removes sink factors

• Methane– Main source bacteria that breakdown waste matter– Main source bogs and swamp lands- increase in

decomposing matter– Sink can be collected & used as a fuel– Sinkstart eating Kangaroo instead of cow.

Anthropogenic Effects

• Anthropogenic Greenhouse Effect– Since 1750 humans have increase CO2 levels

mostly from burning fossil fuels– Deforestation & Agriculture– Industrial activities– Methane has increase 1045 ppb– CO2 has increase 104 ppb