Why the world's climate changed since the last ice age.

External factors:

Solar output: This is energy that comes from the sun. The energy that comes from the Sun changes over time. Measurements made in the 1980s showed that the total amount of solar energy reaching the Earth has decreased by 0.1 %. Although this is not much, if the trend continued fpr 100 years it could influence global climate. It has been predicted that a 1% change in solar output could make the temperature rise or fall by between 0.5 and 1.0 degrees celcuis. It is thought that the activity or sunspots on the Sun's surface affects solar output.

Orbital geogmetry: Orbital characteristics that are responsible for past and possible future climatic changes include:

• The  shape of the Earth's orbit around the Sun varies from nearly circular to elliptical and back to circular again every 95,000.
• The tilt of the Earth's…