Global circulation, climate change and the UK climate

• The poles get less heat than the Equator because the Sun's rays hit at a low angle and are spread over a larger area.
• Air circulates in three cells in each hemisphere: Hadley (0 to 30 degrees), Ferrel (30 to 60) and Polar (60 to 90). Air rises at the Equator (low pressure) and sinks at about 30 degrees (high pressure).
• Evidence for natural climate change includes ice cores, tree rings, pollen, historical records and temperature records. Natural causes include volcanic eruptions, changes in the Sun's output and Milankovitch cycles.
• Human causes of recent warming include burning fossil fuels (carbon dioxide), farming (methane from cattle and rice paddies) and deforestation. This strengthens the greenhouse effect.
• Effects include melting ice, rising sea levels and changing weather. The UK has a south-westerly prevailing wind that brings rain from the Atlantic.

Greenhouse effect

Gases in the atmosphere trap heat that would otherwise escape to space.

Milankovitch cycles

Changes in the Earth's orbit shape, tilt and wobble that affect climate over tens of thousands of years.

Ice core

A long tube of ice from an ice sheet. Air bubbles in it record the past atmosphere.

Prevailing wind

The most common wind direction in a place. In the UK it is from the south-west.

Carbon footprint

The amount of greenhouse gas that a person or group causes.

• Using 'temperatures are rising' as evidence of natural climate change. Evidence is a record such as an ice core, tree ring or pollen.
• Saying melting ice causes climate change. Melting ice is an effect, not a natural cause.
• Saying 'because of climate change' to explain an impact. Give the chain: warmer air melts ice, so sea level rises, so low land floods.

6 questions, 8 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.