paleoclimatology

Question 1

average global temperatures can be obtained from ___________________

Answer 1

ice cores and tree rings

Question 2

what are tree rings?

Answer 2

rings created as the tree grows; amount of growth is determined by amount of rain and the temperature

Question 3

what do wide tree rings indicate?

Answer 3

wet and cool weather

Question 4

what do narrow tree rings indicate?

Answer 4

dry and hot weather

Question 5

what do dark tree rings indicate?

Answer 5

growth during late summer

Question 6

what do light tree rings indicate?

Answer 6

growth during spring

Question 7

how do rings indicate one year?

Answer 7

a light ring + dark ring

Question 8

what do uneven width of tree rings indicate?

Answer 8

tree was leaning to one side

Question 9

what do scarred tree rings indicate?

Answer 9

insects, forest fires, etc

Question 10

why is it that the deeper the layer, the older the ice?

Answer 10

new layers of ice and snow are deposited every year

Question 11

ice cores trap _____ from the atmosphere and _______ from plants

Answer 11

gases / pollen

Question 12

what does the trapped material in ice indicate?

Answer 12

the temperature and concentration of greenhouse gases at that time

Question 13

name 4 pieces of evidence from ice cores

Answer 13

dissolved and particulate matter in the ice
physical characteristics in the ice
the composition of trapped air bubbles
composition of the ice itself

Question 14

what are the 3 naturally occuring oxygen isotopes and what are their characteristics?

Answer 14

oxygen-16: requires less energy to change state (evaporates easily); most common
oxygen-17
oxygen-18: heavier, condenses easily

Question 15

what happens to oxygen isotopes in warm periods?

Answer 15

more oxygen-16 in oceans; less in polar ice

less oxygen-18 in oceans; more in polar ice

Question 16

what happens to oxygen isotopes in cold periods?

Answer 16

less oxygen-16 in oceans; more in ice sheets

more oxygen-18 in oceans; less in ice sheets

Question 17

what does the ratio of oxygen-16 to oxygen-18 indicate?

Answer 17

the temperature of that period in time

Question 18

scientists can also use ____________ from sedimentary rock to create a picture of past climates

Answer 18

fossilized organisms

Question 19

what can fossils and oxygen isotopes indicate?

Answer 19

an idea of what plants were common at a certain time in the past / the temperature of the water aquatic organisms lived in

Question 20

what is a varve?

Answer 20

sedimentary layers formed in glacial lakes

Question 21

when are sedimentary layers thick and light coloured?

Answer 21

in the summer

Question 22

when are sedimentary layers thin and dark coloured?

Answer 22

in the winter

Question 23

if fossils of creatures that live in tropical areas are found in colder regions, ____________

Answer 23

the cold region used to be warmer

Question 24

can we tell whether climate changed suddenly or gradually?

Answer 24

no

Question 25

what does “suddenly” mean in comparison to “gradually”?

Answer 25

a few decades vs millions of years