Evidence For Climate Change

Question 1

What are historical records and why may they be unreliable

Answer 1

Long sequence of temperature records however may have been collected with equipment not as accurate as that used today/human errors/slight changes in temp may not have been measured

Question 2

How can peat bogs provide evidence and why may be unreliable

Answer 2

Study plant and insect remains preserved in peat (accumulation of partially decayed organic matter), anaerobic and often acidic conditions mean decay rate slow
-lots of pollen adapted to move with wind so may not be trapped, only mature trees produce pollen so no data on small, immature trees

Question 3

Why is pollen from peat particularly useful for reconstructing past climates

Answer 3

-plants produce a lot of pollen throughout spring and summer
-tough outer layer that is resistant to decay
-each species has a distinctive type of pollen so can identify the species it came from
-peat forms in layers, carbon-14 dating allows the age of layer to be established
-each species has particular set of conditions it grows best in, if find pollen from species favouring warmer conditions can infer peat was laid down when climate warmer

Question 4

What is dendrochronology and how can it give info on climate and why may it not be reliable

Answer 4

Each year trees produce new layer of xylem vessels, diameter varies according to the climate, wider if conditions better for tree growth (warmer and wetter) however growth also depends on light and CO2

Question 5

How can ice cores be used

Answer 5

Each year a new layer of ice is laid down and air is trapped within the ice, ratio of dif oxygen isotopes in trapped air measured which gives estimate of average air temp eg 18O precipitates readily suggesting colder if more of and CO2 concen can be determined