Climate Change - The Evidence (AQA GCSE Geography): Revision Notes

1.4.1 Climate Change - The Evidence

Ice Cores

1. Ice sheets are made up of layers of ice - a layer is formed each year.
2. Scientists drill into ice sheets to get long cores of ice.
3. By analysing all the gases trapped in the layers of ice, they can tell what the temperature was each year.
4. One ice core from Antarctica showed us how the temperature has changed over the last 400,000 years.

Temperature Records

1. Since the 1850s, global temperatures have been measured accurately using thermometers. This gives a reliable but short-term record of temperature.

Temperature Records - checking ice cores

Pollen Analysis

1. Pollen from plants gets preserved in sediment, 📝at the bottom of lakes.
2. Scientists can identify and date the preserved pollen to show which species were living at that time.
3. Scientists know the conditions that plants live in now, so preserved pollen from similar plants shows that climate conditions were similar.

Tree Rings

1. As a tree grows, it forms a new ring each year - the tree rings are thicker in warm, wet conditions.
2. Scientists take cores and count the rings to find the age of a tree. The thickness of each ring shows what the climate was like.
3. Tree rings are a reliable source of evidence of climate change for the past 10,000 years.

The Earth is Getting Warmer

Earth is Getting Warmer

• Climate change is any significant change in the Earth's climate over a long period. The climate is constantly changing and always has.
• However, recently, the Earth is seeing a rapid increase in global temperatures.
• This is called global warming. This sharp rise in global temperatures over the last century is a human-induced climate change.