Climate change the evidence

Question 1

How long ago was the Quaternary period, which is our most geological time period?

Answer 1

It spanned from about 2.6 million years ago to the present day.

Question 2

In the period before the Quaternary, was the Earth’s climate warmer or colder?

Answer 2

Was warmer and more stable

Question 3

During the Quaternary, did global temperatures shift?

Answer 3

Global temperatures shifted between cold glacial periods that lasted for around 100,000 years, and warmer inter glacial periods lasted for around 10,000 years.

Question 4

How long ago did the last glacial period end?

Answer 4

Around 15,000 years ago since the climate has been warming.

Question 5

Global warming is the term to describe what?

Answer 5

Sharp rise in global temperatures over the last century. It’s a type of climate change.

Question 6

Ice and sediment cores

Answer 6

1) Ice sheets are made up of layers of ice- one layer is formed each year.
2) Scientists drill into ice sheets to get long cores of ice.
3) By analysing the gases trapped in the layers of ice, they can tell what the temperature was each year.
4) The remains of organisms found in cores taken from ocean sediments can be analysed.

Question 7

Temperature records

Answer 7

1) Since the 1850s, global temperatures have been measured accurately using thermometers. This gives a reliable but short-term record of temperature change.
2) Historical records, like harvest dates or newspaper weather reports can extend the record of climate change further back.

Question 8

Pollen analysis

Answer 8

1) Pollen from plants gets preserved in sediment, e.g. at the bottom of lakes or in peat bogs.
2) Scientists can identify and date 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.

Question 9

Tree rings

Answer 9

1) As the 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