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