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