Physical Causes of Climate Change

Question 1

Explain tilt

Answer 1

Every 41,000 years, there is a change in the tilt of the Earth’s axis.
A greater tilt means more/less sunlight in polar regions depending on the time of year

Question 2

Explain wobble

Answer 2

The axis currently points to the Polaris star so the Northern hemisphere has winter in December (further from the sun) Summer in July (closer to the sun).
Every 13,000 years the “wobble” will shift towards the Vega star so the Northern Hemisphere will have winter in July (further from the sun), Summer in December (closer to the sun).

Question 3

Explain stretch

Answer 3

Over a 97,000-year cycle, the Earth’s orbit stretches.
The temperatures drop when the Earth is further from the sun

Question 4

Sunspots

Answer 4

Sunspots are dark spots which appear on the sun which follow an 11 year pattern
If sun spot activity is higher then subsequently global temperatures will increase.
E.g. The Little Ice Age (1450-1700) has been linked to very low sunspot activity.

Question 5

Volcanic eruptions

Answer 5

Millions of tonnes of ash, dust and droplets of sulphur are put into the atmosphere.
This lowers global temperatures as in increases reflection meaning less insolation reaches the Earth’s surface.
E.g. The Mount Pinatubo eruption in 1991. This resulted in average temperatures falling by 0.5 Degrees Celsius.

Question 6

Ocean currents

Answer 6

Retreating ice caps release additional fresh water leading to changes in oceanic circulation.
These changes affect the climate of the land that they flow past.
E.g. the last ice age was caused by the North Atlantic Drift altering its course.

Question 7

Melting permafrost

Answer 7

As places within the Arctic Circle are exposed to warmer temperatures, the permafrost found in these regions is slowly melting.
Melting permafrost releasing large quantities of the greenhouse gas methane.
This contributes to the enhanced greenhouse effect and raises temperatures.