1 Climate Change We have talked about global warming and an increased temperature… but should we also have to worry about another possible Ice Age?

2 What happens when we run out of fossil fuels and are no longer adding extensive greenhouse gases into our environment…? ?

3 Climate Change: ICE AGESIce Age, a time when ice sheets and alpine glaciers were EXTENSIVE, and advanced and receded repeatedly over LONG PERIODS of time.

4 Causes of the Ice Age (page 331)Planetary System and Earth’s position Orbit and distance from the sun (eccentricity, perihelion/aphelion) Tilt (precession) Plate Tectonics: shifting landmasses (Pangaea) Hydrosphere ocean currents and climate ocean level changes Atmosphere gases (greenhouse effect) Biosphere: population growth and extinction Contribution to/reduction of greenhouse gases Geosphere: Volcanic Eruptions, Mountains and Albedo Lead the students to these topics and assign them to do quick research. Put their findings on a white board for discussion later

5 Earth’s Orbit Eccentricity: elliptical orbit.the distance to the Sun at perihelion is only about 3% less than its distance at aphelion. We are farthest on _________ We are closest on __________ The eccentricity of the Earth's orbit (how elliptical it is) also changes over very long periods of time, about 100,000 years from almost zero (circular orbit) to about three times its current value.

6 Earth’s Motion Obliquity: tilt on it’s axisbetween ° Varies every 41,000 yrs The greater the tilt, the more extreme the seasons Precession: “wobbles” as it rotates Every 21,000 yrs. So… when the earth is at its extreme tilt and farthest from the sun it its orbit, then we experience extreme “cold spells”

7 Plate Tectonics: PangaeaDue to plate tectonics, land masses have moved. We were closer to the poles and farther from the equator at different times Pangaea, 250 mya Evidence: Coal beds in Antarctica Glacial features in Africa and India

8 Shifting land masses changed ocean currentsShifting land masses changed ocean currents. Circulation of warm and cold ocean currents is blocked

9 How do Ocean Level Change during Ice Ages?

10 CO2 (greenhouse gasses) levels in the atmosphere have fluctuated.Increase CO2 causes global warming Decrease CO2 causes global cooling

11 How do the following affect CO2?Population Increases Population Decreases

12 Geosphere Volcanoes add Atmospheric GasesMountains have snowy tops with Albedo: the amount of solar energy reflected by the Earth’s surface. White snow reflects (90%) of Sun’s energy = colder temperatures = more snow = even less energy absorbed etc. Volcanoes add Atmospheric Gases

13 Plate tectonics (convergent plates) create mountains that have high elevations producing snow and glaciers.

14 During the last Ice age, How much of the earth was covered with ice?About 1/3rd

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16 When have we had an Ice Age?There has been more than one “ice age”. As far back as 2 billion years ago (snowball earth) Most recent “Ice Age” began 2 million years ago and ended about 15,000 years ago. The last ice age, called the “Wisconsin” episode was during the Pleistocene epoch and about half of Illinois was covered

17 Evidence: moraines, erratics

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19 Effects: What happened to the Mississippi RiverEffects: What happened to the Mississippi River? Where did the Illinois River come from?

20 The Great Lakes

21 So WHAT is a Glacier? A thick mass of ice that forms over land from the compaction and recrystallization of SNOW (firn)

22 WHERE glaciers can form…North and south poles. (Continental) Cold climate year-round High elevations in mountains. (Valley) Exist on all continents except Australia. Earth’s Largest Glacier

23 Mt. Kilimanjaro, Africa Latitude: 3Mt. Kilimanjaro, Africa Latitude: 3.07 degrees South of Equator Elevation: 19,335 feet

24 Continental Glaciers Cover large landmasses like Antarctica and Greenland. Can be a mile thick in places. Mostly circular or oval in shape Spreads out in all directions Also called an ice sheet Some places the ice reaches the sea and can break off into icebergs. (Calving: when pieces break off of glaciers.)

25 Antarctica Earth’s largest continental glacier

26 Greenland ice sheet

27 + - The glacial budget $$ Figure 6.7 Figure 6.7

28 What is the Snowline (Equilibrium line)Definition: (page 318) The lowest elevation with permanent snow occuring in the summer

29 Elevation of the snowline on a mountain (glaciers formation) decreases as the latitude increases Can Illinois have Glaciers? Pg. 318

30 Concept check advance, recede, stationary1. If more snow accumulates in the winter than can melt in the summer, the glacier will __________ If summer melting exceeds snowfall then the glacier will ________________ 3. A glacier will remain stationary if …..

31 1. Is the glacier ADVANCING, RECEDING or STATIONARY. LABEL THE GRAPH 21. Is the glacier ADVANCING, RECEDING or STATIONARY? LABEL THE GRAPH 2. Compare glacier budget of accumulation vs melting 3. Describe the climate during the winter, summer White board Activity

32 How do we escape an Ice Age?Are we on the path for another Ice Age?

33 Causes of the Ice Age The Earth is a dynamic planet – it is constantly changing. In what ways? The Earth System is part of a larger system (solar system) Earths has 4 spheres (hydrosphere, geosphere, atmosphere, biosphere). How have each of them contributed to the Ice Age? What processes warm the Earth and prevent us from being in a continuous Ice Age? What factors could trigger the onset of an Ice Age?

34 Ice Ages: groups white boardsBrainstorm and list several possible factors that may have caused the ice ages: Combine ideas onto board. Write a questions for each possible cause Divide the questions within your group. Research and answer the questions on the boards

35 Mass Extinctions

36 On a sheet of paper: True or False?_____ 1. Glaciers are only at the north and south poles. _____ 2. A glacier is solid ice. _____3. Antarctica is covered by a glacier. _____4. There could never be a glacier at the equator. _____5. All glaciers move. _____6. Glaciers flatten the land. _____7. When glaciers melt they back up. _____8. Glaciers can carve out valleys. _____9. The Great Lakes were formed by glaciers _____ 10. There has been one Ice Age .

37 Glacier Quiz!

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40 Research List many, many, many things that you see that relate to glaciers, and ice age Write questions that you have. Question “bad science” List “good science” Select ONE to research. Write a research QUESTION One page (with pictures) One source