1. Dynamics of Climate Change

2. Energy Transfer in the Climate System
Earth’s climate is a complex system.
A system is a group of independent parts that work together to form a single, functioning whole.
An open system is a system in which energy and matter cross the system’s boundary. (your body)
A closed system allows energy but not matter to cross the boundary of the system. (The Earth’s climate system)
As a closed system, Earth must constantly cycle the matter and energy within it’s boundary.

3. Interactions among different forms of matter and energy in Earth’s climate system create feedback loops.
A Feedback loop is a process in which part of a system’s output is returned to the input.
In the Earth’s climate system, many feedback loops affect the conditions of the atmosphere, ocean and land.

4. A positive feedback loop acts to increase the effects of the interacting parts.
Example: effect of melting ice, decreases albedo (reflected light of surface), which increases warming, which increases the amount of melting ice, and so on.
The small initial change in climate can lead to larger and larger changes.

5. Negative feedback loops decreases the interacting parts and help maintain the system’s equilibrium.
Checks and balances to prevent, slow or reverse change in a system.
Example: global warming increases rate of evaporation, increased water in atmosphere creates clouds, clouds create more albedo, which produces a cooling effect.

6. Types of Energy Transfer
Radiation: transfer of energy as electromagnetic radiation.
E.G. Sun to Earth, heat from fire, etc.
Conduction: transfer of energy between 2 objects in direct contact. Moves from an area of high heat to lower heat.
E.G. hot plate on stove to frying pan to egg.
Convection: transfer of thermal energy by highly energized molecules.
E.G. lava lamp

7. Energy Transfer in Atmosphere
Land and water gain thermal energy by absorbing the Sun’s short-wave radiation.
As Earth warms, it emits long-wave radiation to the atmosphere, which heats the air and contributes to greenhouse effect.
Conduction heats the air through collisions between molecules in the ground and in the air.
Convection moves warm air from close to the ground upward and cool air from higher in the atmosphere downward.

8. Convection, Conduction and Radiation transfer heat in Earth’s Atmosphere

9. Energy Transfer in the Oceans
Uneven heating on Earth creates winds.
Winds create currents of water that redistribute thermal energy at the ocean surface.
Deeper, colder currents also move slowly along the ocean floor
Like air masses, large masses of water can move vertically and horizontally.
Cold water = dense and sinks, pushing warm water out of the way
Salt water = dense and sinks.

10. Temperature, salinity, density of water create continuous, twisting ocean current that mixes ocean waters.
Sometimes called the “Great Conveyor Belt”
This pattern is known as thermohaline circulation.
Creates a global system of thermal energy distribution

11. Global Warming and Thermohaline Circulation
Scientists are worried that global warming will affect the current pattern of circulation.
Higher temps  increased ice melting increases fresh water decreases salt content in northern water
Higher temps  increased evaporation increased salt levels in tropics
Changes in ocean circulation patterns could have a negative effect on living things (manta ray) in the ocean by changing patterns of upwelling.
Upwelling brings nutrients from sea floor to surface currents.

12. Energy Transfer
The importance of winds and ocean currents to global climate is seen best when there is a disruption to the system.
Every few years in the tropics, there are events called El Nino and La Nina.

13. El Nino Winds blowing west weaken and might reverse
Warm waters in the western Pacific move eastward, preventing cold water from upwelling
Can trigger changes in precipitation and temperature across North America.
Heavy rains in California can lead to landslides

14. La Nina
Stronger than normal winds push warm Pacific waters farther west, towards Asia.
Cold, deep-sea waters well up strongly in the Eastern Pacific
Colder temperatures to northwestern North America.
Moisture pushed away from N.America, parched lands.

15. Earth’s Energy Budget
Nearly a third of solar energy reaching Earth is reflected back.
The 70% that is absorbed warms the ground, water, and air.
The energy budget is a description of the total energy exchange within a system; how much energy enters from the Sun and how much leaves the Earth system.

16. Percentage of Absorbed and Reflected Energy

17. Greenhouse Gases
The concentration of carbon dioxide in Earth’s atmosphere increased from 315 parts per million (ppm) to 370ppm.
99% of the atmosphere is made up of nitrogen gas and oxygen gas.
Neither absorbs infrared radiation or contributes to greenhouse gases.
Carbon dioxide and water are the 2 most abundant greenhouse gases in our atmosphere.

18. Water Vapour? Responsible for 65-85% of greenhouse effect
Water is not added or removed to the atmosphere in significant amounts by humans.
Temperature does control the amount of water in the atmosphere.
Higher temperature = more evaporation

19. CO2 Sources and Sinks
A sink is a process that removes greenhouse gases from the atmosphere.
Plants are sinks
Burning of fossil fuels and animal respiration are the major sources
Phytoplankton (microorganisms) can absorb a lot of carbon dioxide as well.

20. Methane: greenhouse gas
Produced in wetlands (bogs and swamps), rice paddies, termites and cattle naturally.
Landfills, processing coal and natural gas and manure also emit methane.
Suggestions? Make cows wear backpacks to capture the methane and use it as a fuel, feed cows clover and alfalfa to reduce methane, stop eating beef.

21. Methane backpack!

22. Ozone
Ozone (O3) occurs naturally in the atmosphere and blocks UV radiation from the Sun.
Since 1970, there has been a slow decline in the total ozone and a “hole” appeared over Antarctic.
Not actually a hole, just an area where the ozone is thinning more than other areas around it.
Cause: human-made gases that contain chlorine

23. Ground-Level Ozone Smog-forming pollutant
Produced when sunlight reacts with chemicals and vehicle exhaust (hydrocarbons and nitrogen oxides)
Can contribute to global warming.

24. Halocarbons
Formed when carbon is mixed with a halogen (iodine, fluorine, chlorine)
Human-made
Chlorofluorocarbons (CFCs) are best known in solvents, cleaners and coolants in fridges and air conditioners.
Absorb infrared radiation so they are greenhouse gases and also break apart ozone molecules
Remain in atmosphere for so long and continue to do damage
Banned in 1987.