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Lecture 9

Lecture 9

Earth Sciences
Course Code
Christine Burton

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GLG205 t 9
Climate is influenced by 5 components:
Potential causes of climatic change over the geologic past
- Shape and location of continents and oceans
How has the atmosphere changed over time?
- Oxygen as a waste product of Cyanobacteria
- Inhibit convection because of magnetic activity
- Sunspots have an (approximate 11 year cycle
Orbital parameters
- Perihelion t when earth closest to sun
- Aphelion t when earth furthest from sun
o Northern hemisphere summer
o Result in not all the ice melting during summer
- Axial tilt t how much the earth is tilted
Orbital fluctuations
- v]]ÇZZ[
- Æ]o]o~}o]µ]ÇZ}oo[
- d]u}(]Zo]}v~]}vZÁ}o[
- 30 percent greater than
- More tilt means more severe seasons
- If a hemisphere is pointed towards the sun at perihelion, that hemisphere will be pointing aay at
aphelion, and the difference in seasons will be more extreme
Ice sheets can build up if a supercontinent is at a pole
- Pangea was at the south pole so even Africa was once glaciated
The last 5 million years
- Ice ages, when north America and moth Europe host large ice sheets, alternate with brief warm
- Ice sheets cut modern landscapes of Canada from the mountains of the west to deep coastal
inlets of the great lakes
Deep ocean
- Dumping enormous volumes of ice and fresh water into the north atlantic
What paleoenvironmental sinal
- Ice sheets pick up a lot of dirt and sediment as they move and deposits these large sediments
into the ocean
- Aerosols that came from the volcano reflected solar radiation back to space
Factors influencing climate
- Troposphere
Ice cores
- When ice freezes, it traps gas bubbles in it that preserves gas during time it froze
sea sediment
- Dead organisms equalize with oxygen ratio to tell us how much oxygen at the time
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