1.2 Natural Causes Of Climate Change

Question 1

What are the four different natural factors that have caused world climates to change over the last 400,000 years?

Answer 1

Orbital changes
Volcanic activity
Asteroid collisions
Solar output variations (sunspots)

Question 2

Orbit, Tilt and Wobble – what are these and why do they cause variations?

Answer 2

Orbit
- changes from circular (warmer) to elliptical (colder and when glaciation periods occur) - every 100,000 years
Tilt
- angle of tilt of the Earth shifts from 22.1° to 24.5° causing different climates than previously x every 40,000 years
Wobble (precession)
- Earth’s rotation on the axis is not perfect and creates slight variations in seasons - every 24,000 years

Question 3

Why is the emission of dust important in volcanic eruptions and asteroid strikes for causing a cooler climate?

Answer 3

Asteroids
- lots of dust is flung into the atmosphere and partially block out the sun, cooling he surface below
Volcanic activity
- large volumes of ash and sulphur dioxide gas is emitted into the stratosphere blocking the sun’s rays, cooling the surface below

Question 4

Is a sun spot hot or cold? How often does this vary?

Answer 4

Hot

A variation every 11 years

Question 5

How does ice cores in Antarctica tell us about previous temperatures in the most recent quaternary (2.5million years)?

Answer 5

• sections of ice deep inside glaciers
• air bubbles are found inside from when the ice was formed (very long ago)
• analysing the air bubbles gives very accurate results to what the climate was like
• tested with the chemical composition of oxygen

Question 6

Give three pieces of evidence which show the earth’s climate was:

• Warmer
• Colder

Answer 6

Warmer

• Roman warm period (grape vines in Britain)
• Medical warm period (historical evidence)
• large scale volcanic eruptions

Colder

• The Ice Age (ice cores and historical evidence)
• The Dark Ages (historical evidence)
• The Little Ice Age (historical evidence)