Evidence For Climate Change

Question 1

What is a glacial period?

Answer 1

A colder period of time, where about 33% of the Earth is covered in ice.

Question 2

What is an interglacial period?

Answer 2

A warmer period of time, where about 10% of the Earth is covered in ice.

Question 3

What evidence is there for long-term climate change?

Answer 3

Ice Cores :
- Layers of ice contain a ‘chemical signature’ of past atmospheric conditions in air bubbles.
- Air bubbles contain atmospheric gases ( such as CO2 ), from which the past chemical composition of the atmosphere can be measured.
- By analysing the composition of water molecules within the ice, scientists can calculate a gradual temperature change over thousands of years.

Sediment Cores :
- Micro-fossils ( foraminifera ) are layered in chronological order over millions of years.
- Distribution of different species can be analysed to determine certain environmental conditions.

Proxy Data ( Nature ) :
- Mega fauna fossils are found in landscape features such as canyons.
- Provide an insight into how organisms adapted to certain changing environmental conditions.

Question 4

What evidence is there for medium-term climate change?

Answer 4

Glacial Retreat :
- Glaciers and ice sheets are melting, providing evidence for a warming climate.
- Photographic evidence is compared between different years to analyse the extent of retreat.

Dendrochronology :
- Tree rings are used to approximate the climate up to 10,000 years ago.
- Thicker rings - warmer and wetter climate.
- Thinner rings - colder and drier climate.

Anecdotal Evidence :
- Ship logs, diaries and paintings suggest what the environmental conditions were like hundreds of years ago.
- Not as reliable as proxy data.