Natural Causes of Climate Change

Geography: Edexcel IGCSE, topic 3.1.1

Natural Factors and Climate Change

Below are some natural factors that are potential causes of climate change:

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 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.

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.

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.

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.