Climate Change

Question 1

Name three pieces of evidence for global warming

Answer 1

Temperature records

Dendrochronology (tree rings)

Pollen in peat bogs

Question 2

How does dendrochronology work?

Answer 2

• Most trees produce one ring per year
• The thickness of the ring depends on the climate when the ring was formed; warmer climates form thicker rings as the conditions for growth are better
• Scientists take cores through the tree trunk and date each ring by counting them back from when the core was taken
• The thickness of the ring indicates how the climate was in that year
• Rings from the last few decades have gotten much thicker, hence evidence of a warmer climate

Question 3

How do peat bogs provide evidence for global warming?

Answer 3

• Pollen is often preserved in them
• Forms as layers so pollen is preserved over time
• Scientists take cores from the bogs and extract pollen grains from the different layers
• Only fully grown plants produce pollen so samples only give evidence for these plants during that time
• Previous climates where the plants lived, indicated by the pollen, is compared with the climate in which the species of plant lives today
• Plant species vary as climate changes so preserved pollen will vary as climate changes over time
• A gradual increase in pollen from a plant species that’s more successful in warmer climates shows a rise in temperature

Question 4

Define global warming

Answer 4

The recent rise in global temperatures