lecture 4 & 5

Question 1

What do the EPICA and Vostock Antarctic Ice Core show?

Answer 1

That we had 5 interglacial periods in the last 450 000 years

Question 2

What is today’s interglacial period called?

Answer 2

The Holocene

Question 3

Which Marine Isotope Stage is the Holocene?

Answer 3

Marine Isotope Stage 1

Question 4

What are the two large-scale glaciations of the Holocene?

Answer 4

The Antarctic ice sheet and the Greenland ice sheet

Question 5

What is the total sea level equivalent of the Antarctic and the Greenland ice sheets?

Answer 5

65 meters

Question 6

What Marine Isotope Stage was the global Last Glacial Maximum (LGM)?

Answer 6

Marine Isotope Stage 2 (MIS2)

Question 7

When was the global Last Glacial Maximum?

Answer 7

26,5-18 ka (years ago)

Question 8

What were the large-scale glaciations of the Last Glacial Maximum in the Northern Hemisphere?

Answer 8

Ice sheets in North America and northern Europe.
The Greenland ice sheet was more extensive but thinner.
Large ice caps in Iceland and Kamchatka

Question 9

What ice sheets did the North American ice sheet complex during Last Glasial Maximum consist of?

Answer 9

Cordilleran, Laurentide and the Innutian ice sheets

Question 10

What ice sheets did the European ice sheet complex during Last Glacial Maximum consist of?

Answer 10

British-Irish, Fennoscandian, and Barents-Kara Sea ice sheets.

Question 11

What were the Last Glacial Maximum large-scale glaciations in the southern hemisphere?

Answer 11

Patagonian Ice Sheet, Antarcitc Ice Sheet, and an ice cap in New Zealand

Question 12

Where did we have growth of ice sheets during the Last Glacial Maximum?

Answer 12

In the Northern Hemisphere

Question 13

What temperatures did we have during the Last Glacial Maximum?

Answer 13

Only 4°C lower global temperature

Question 14

Where were the largest differences in temperatures during the Last Glacial Maximum?

Answer 14

In polar regions, especially formerly glaciated areas (8-30°C cooling).

Question 15

Why was the climate colder in formerly glaciated regions during the Last Glacial Maximum?

Question 16

Which was the largest ice sheet during Last Glacial Maximum?

Answer 16

The Laurentide ice sheet

Question 17

How thick was the Laurentide ice sheet during Last Glacial Maximum?

Answer 17

Up to 4.5 km thick

Question 18

Where is oxygen present and exchanged between?

Answer 18

Hydrosphere, atmosphere, cryosphere, lithosphere and biosphere

Question 19

What does an oxygen atom consist of?

Answer 19

8 protons and varying amounts of neutrons in its nucleus

Question 20

When it is considered light, how many neutrons does an oxygen atom consist of?

Answer 20

8 (atomic mass = 16 (8 protons + 8 neutrons))

Question 21

When it is considered heavy, how many neutrons does an oxygen atom consist of?

Answer 21

10 neutrons (atmic mass = 18 (8 protons + 10 neutrons)

Question 22

Is there a fixed amount of light and heavy oxygen isotopes in the world?

Answer 22

Yes

Question 23

Where do the heavy and light isotope ratios in oxygen differ?

Answer 23

In the air, oceans, and ice sheets

Question 24

What does the transfer of oxygen isotopes through the earth’s system depend on?

Answer 24

Mass and temperature

Question 25

What happens with oxygen isotopes when the ocean water evaporates?

Answer 25

H2O with the lighter oxygen isotope evaporates slightly more readily than H2O with the heavier oxygen isotope.

Question 26

What is fractionation?

Answer 26

The process of favoring the transfer of one isotope over another

Question 27

What does fractionation change?

Answer 27

The oxygen isotope ratio of the atmosphere and ocean.

Question 28

How does fractionation change the isotope ratio between the atmosphere and the ocean?

Answer 28

More O16 evaporates into the atmosphere, leaving more O18 in the ocean. When the light isotopes return via rivers, the system is in balance.

Question 29

What typically happens when the ocean is isotopically heavy (more 18O in the Ocean)?

Answer 29

Glaciers expand, forming a new reservoir of isotopically light water on the land. Sea level drops.

Question 30

Why is snow depleted in 18O?

Answer 30

Because the heavier oxygen isotopes rain out first

Question 31

What does human dispersal have to do with glaciers and climate?

Answer 31

Due to there being significantly more land than at present and land bridges between continents and islands. Humans could walk where there is ocean and water today.

Question 32

How many years of climate change can we measure from sediment cores and oxygen isotopes?

Answer 32

Five million years

Question 33

What is measured in ice cores?

Answer 33

The decrease in 18O and increase in 16O during cold periods, and the other way around in marine sediment cores.

Question 34

When and where could humans walk from the Asian continent to the American continent?

Answer 34

25 thousand years ago, over the Bering Land Bridge (during the Last Glacier Maximum)

Question 35

When and why did humans walk from North America toward the South?

Answer 35

When an ice-free corridor opened between the Cordilleran and the Laurentide ice sheet about 13 000 years ago

Question 36

When and why did humans walk from Asia toward Australia?

Answer 36

65 thousand years ago,

Question 37

When and why did humans arrive in Scandinavia?

Answer 37

12 000 years ago, when the Fennoscandian ice sheet melted.

Question 38

When was the last glacial period?

Answer 38

Between the end of the Eemian and start of the Holocene (115 000-11 700 years ago). The Ice Age.

Question 39

What was the global sea level during Last Glacier Maximum?

Answer 39

120-130 meters lower than today.

Question 40

What did humans find when they crossed Beringia?

Answer 40

Ice (The Laurentide and Cordilleran ice sheets)