Long Term and Short Term Changes in Climate; The Albedo Effect

1. Long Term and Short Term Changes in Climate; The Albedo Effect

2. Long Term Climate Change The Cause and Effects

3. Climate Change What and How? • Long term climate change occurs over million of years. • There are many causes to L.T.C. changes, such as changes in earth’s orbit, shifting of continents, and cycle of climate change

4. Climate Change Continental Drift • The movement of continents. • A long time ago, there was a single continent. • Over millions of years, the continent “broke apart” to form present day Earth.

5. Climate Change Continental Drift • Movement of land affects the climate in different ways. • Changes in ocean currents, wind patterns and land mass. • The result: heat transfer is affected.

6. Continental Drift. The Animation.

7. Cycles • Not every type of climate change is permanent. • Some occur in cycles. • Changes in Earths orbit also causes changes in climate and it occurs in cycles.

8. Causes of long term climate change Changes in Orbit • Specific term: Eccentricity • The Earth’s orbit around the sun changes shape. • It changes after around 100 000 years. • The reason: Jupiter and Saturn’s gravitational pull.

9. Causes of long term climate change Changes in Orbit • When the orbit changes, Earths distance from the sun is either consistent or varied. • When the distance is consistent, the seasons are mild. • When The distance is varied, the climate tends to be more “extreme”.

10. Causes of long term climate change Changes in Orbit • Change in orbit is a slow transition from almost circular to elliptical. • The change is very slow! • Right now earths orbit is elliptical.

11. Causes of long term climate change Tilt • The earth slowly tilts back and forth on its axis. • The earth tilts around 22.1º to 24.5º. • Happens over 41000 years. • Currently, earth is tilted 23.5º. • This angle is decreasing.

12. Climate Change Tilt • As the tilt increases, the so does the difference in temperature of seasons. • The Earth also “wobbles” around its axis.

13. Short Term Climate Change

14. Short Term Factors • Volcanic eruptions • Changes in the Sun’s radiation • Changes in air currents • Changes in ocean currents

15. Volcanic Eruptions • Rocks, dust and gases are released into the atmosphere • The sulfur dioxide particles which are released reflect the Sun’s energy back to space • Since there is less energy, the Earth cools down temporarily

16. Volcanic Eruptions • Example on pg. 351 (Fig. 7)

17. Air and Ocean Currents • Changes in thermohaline circulation can cause changes in climate • Thermohaline circulation is the flow of water around the world’s oceans driven by differences in temperature and salinity • There are some changes which occur regularly, an example is El Nino

18. Ocean Currents

19. (cont.) • Ocean currents affect climate • Example: The air above warm ocean currents is heated. The land is warmed and rain is produced when this warm, moist air reaches land. • This is why air and ocean currents can affect climate

20. El Nino • Occurs every 3 to 7 years • Prevailing winds temporarily change direction • Ocean currents change • Warm water is pushed towards S. America • Because of this, the west coast of S. America gets warm, wet weather

21. El Nino • On pg. 353 (Fig. 8) in textbook

22. The Sun’s Radiation • The amount of radiation the earth receives affects climate • Small changes can affect the climate of the earth • When the amount of radiation is lower, there is less energy, the climate cools • If radiation increases, there is more energy, the climate warms

23. The Albedo Effect

24. Feedback Loops • Small changes can have large effects • This is because the small changes can be made bigger because of feedback loops • A positive feedback loop increases the original cause • A negative feedback loop decreases the original cause

25. Water Vapour and Feedback Loops • An example of positive feedback loops is the water vapour in the atmosphere • More water vapour forms since if the climate warms. Water vapour is a greenhouse gas and traps radiation. This further warms up the earth. • It is the same when the climate cools. Less water vapour is formed and the climate cools even more

26. Albedo • This is the radiation which is reflected by a surface • Different surfaces have different albedos, an example would be ice which reflects much of the sun’s radiation • The albedo of a planet is a measure of how much radiation is reflected back when the sun shines on it • Earth has an albedo of 0.30-0.40

27. Albedo Diagram

28. Albedo Effect • This is an important feedback loop in Earth’s climate • It is a positive feedback loop • Relationship between ice on surface of the Earth and the avg. temperature • If the temperature increases, ice melts and less radiation is reflected which further increases the temperature • If it decreases, ice forms and more radiation is reflected

29. The Albedo Effect

30. Questions • What are the long term changes affecting the earth? • What is continental drift? • What can the movement of large land masses cause? • Does the orbit of the earth change? How? • What are the short term changes which can affect climate? • How do volcanic eruptions cause changes in climate?

31. Questions (cont.) • What is albedo? • What is the albedo effect? • What happens if the temperature of the planet increases? • What happens if the teperature of the planet decreases?