1.2.3 Natural Causes Of Climate Change

Question 1

Asteroid collisions

Answer 1

• When asteroids collide with the Earth, huge amounts of dust particles get thrown up into the atmosphere.
• These dust particles reduce the amount of sunlight reaching the Earth’s surface. This causes global temperatures to fall.
• This is unlikely to explain recent changes in the Earth’s climate.

Question 2

Orbital changes

Answer 2

-The Earth’s orbit around the Sun changes from circular to elliptical and back to circular over a period of 96,000 years. This is known as Milankovitch cycles.
-When the Earth is closer to the sun, more of the sun’s radiation will reach the Earth, warming it.
-Orbital cycles could explain the interglacial eras.
-The Earth’s tilt changes over a cycle of 41,000 years.
-The Earth’s axis wobbles on on a cycle of 22,000 years.
—> These cycles affect the amount of solar radiation the Earth receives - the more solar radiation it’s exposed to, the warmer it gets.

Question 3

Solar output variation

Answer 3

The Sun’s energy output changes in cycles. It is possible that a period of high output could increase the Earth’s temperature, however, the scientific consensus is that solar output variation cannot explain recent global warming.

Question 4

Volcanic activity

Answer 4

-Very large volcanic eruptions can change the atmosphere.
—> Particles can reflect the Sun’s radiation away from Earth, cooling it down. This can be described as a volcanic winter.
—> Volcanic eruptions also release Carbon Dioxide, which is a greenhouse gas.
-However, volcanic winters only last for a few years and would cool the earth down.
-Volcanoes don’t produce enough CO2 to explain global warming over 150 years.