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14.3 – CLIMATIC CHANGES
Ice Age
Periods of extensive glacial coverage Lots of ice sheets
Average global temperature decreased by about 5°C
Most recent ice age ended about 10,000 years ago Right now we are
experiencing a warm period Interglacial intervals
Short-Term Climatic Changes
Seasons = short-term periods of climatic change caused by regular variations in daylight, temperature and weather patterns Result from changes in the amount of
solar radiation received When the North pole points
towards the sun, the Northern Hemisphere experiences summer When it points away, it is winter
El Niño
Band of warm ocean temperatures that develops off the coast of South America
High-pressure system and weak trade winds allow warm water to move towards South America
Causes warmer and wetter conditions
Natural causes for climatic changes
Solar Activity E.W. Maunder discovered
that changes in Earth’s climate coincided with cycles of low sunspot activity Little Ice Ages Europe experienced bitterly cold winters and below-normal temperatures all year long
Natural causes for climatic changes
Earth’s orbit = Elliptical orbit When Earth is closer to sun, temperatures are warmer than normal
When orbit is farther away from sun, temperatures are below normal
Natural causes for climatic changes
Earth’s tilt = the angle of the tilt of Earth’s axis is 23.5°
Change in tilt affects differences in seasons
Scientists hypothesize that changes in the angle can cause ice sheets to form near the poles
Earth’s wobble
Every 26,000 years or so, the Earth wobbles as it spins on its axis
Currently axis points towards the North Star
Determines seasons In about 13,000 years,
scientists believe the axis will point towards Vega and our seasons will flip-flop
Volcanic activity
Particles released during volcanic eruptions trigger climate changes
Dust and ash clog the atmosphere and block solar radiation
High volcanic activity = cool climatic periods
In-Class Assignment/Homework 14.3 WKT
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