Physical Environment of the Boreal-Arctic Region

Question 1

t/f
northern areas vary vastly in elevation

Answer 1

true

northern conditions are exacerbated at higher elevations

Question 2

The ___ ridge divides the Arctic ocean into 2 major basins, and influences
- ____ circulation
- marine ___
- ___ movement

Answer 2

Lomonosov ridge

water circulation
marine life
ice movement

Question 3

Why does the geology of the north matter? Give 2 reasons

Answer 3

• we need to know how the rocks/ soils work in order to know how the plants and animals work
• also, territorial claims (diamond extraction is changing the north)

Question 4

The ___ Expedition in 1845 was trying to find the northwest passage and never returned

Answer 4

Franklin

Question 5

t/f
Canada is the largest producer of diamonds in the world, and it’s harming our northern ecosystems

Answer 5

false

2nd largest after Russia
but it IS harming our north!

Question 6

what’s a main problem with pipelines in the north?

Answer 6

They have to be above ground because the ground is frozen
This disturbs the habitat even more
(natural gas & oil)

Question 7

How old are 75% of the rocks in the north?

Answer 7

Precambrian- Archean and Proterozoic

543 million yrs to 4.5 billion years old

Question 8

The Canadian Shield is about __% of Canada’s land, and is very old rock

Answer 8

50%

Question 9

What are the 3 basic classes of rock? (with a brief explanation of each)

Answer 9

1. Igneous: formed by cooling & solidification of molten earth material (mostly silicate minerals)
2. Sedimentary: formed at or near earth’s surface- accumulation and lithification of sediment or precipitation from solution
3. Metamorphic: formed by altering preexisting rocks (by changing conditions like temp/ pressure)

Question 10

t/f
millions of years ago there were forests in the arctic with huge biomasses

Answer 10

true

we know because preservation is so good in these conditions: mummification of stumps & litter etc

Question 11

Where is Axel heiberg island? What used to be there?

Answer 11

an uninhabited island in nunavut

~45million years ago there were forests there (similar to temperate old-growth forests): represented max productivity achievable near the poles

• also Champsosaurs (like a crocodile) lived there with fish and turtles ~86 million years ago
  = climate in the north was much warmer than it is today

Question 12

Why is the arctic warming so much faster than other areas?
Give 5 explanations

Answer 12

1. As snow and ice melt, darker land & ocean surfaces absorb more solar energy
2. more of the extra trapped energy goes directly into warming rather than into evaporation
3. the arctic atmosphere layer that’s warming is thinner that at lower latitudes (atmosphere thicker at equator and thinner at poles)
4. with sea ice retreat, solar heat absorbed is easily transferred to the atmosphere
5. alterations in atmospheric and oceanic circulation

Question 13

current atmospheric CO2 concentration is ___ ppm

Answer 13

419

Question 14

List 5 of the most influential greenhouse gases

Answer 14

1. CO2 (very abundant but doesn’t persist long)
2. Methane
3. Nitrous oxide N2O
4. SF6 Sulfur hexafluoride
5. Water vapour

Question 15

How does the production of CH4 create positive feedback?

Answer 15

CH4 in atmosphere causes warming because it’s a GHG

warmer= more decomposition occurs

more decomp= more CH4 released

Question 16

What are the 3 components of the Milankovitch cycles? What do they do?

Answer 16

1. Eccentricity= shape of earth’s orbit around the sun
2. Axial tilt (23.5 degrees today)
3. Precession= wobble of earth on its axis

these drive our seasonal variation

Question 17

What would less axial tilt result in?

Answer 17

= solar radiation more evenly distributed between summer and winter (cooler summers, warmer winters)

less axial tilt would promote glaciation!

Question 18

What’s the periodicity of each of the Milankovich cycles?

Answer 18

Eccentricity: 100,000 yrs

Axial Tilt: 41,000 yrs

Precession: 23,000 yrs

Question 19

How do Milankovich cycles start/ end ice ages?

Answer 19

The amount of summer sunshine on northern continents is crucial
- if it drops below a critial value, snow from the past winter doesn’t melt in the summer –> an ice sheet starts to grow as more snow accumulates

• more ice = more ice positive feedback b/c of higher albedo

Question 20

t/f
Milanovich cycles have a significant effect on the decade- century timescale

Answer 20

false
good for explaining long-term changes in climate

Question 21

Clouds and Earth’s surface reflect some ___ solar radiation back out to ___. Some is absorbed by the ___ and the rest is absorbed by earth’s ___

Answer 21

incoming
space
atmosphere
surface

Question 22

What happens to the solar energy absorbed by Earth’s surface?

Answer 22

it’s emitted as weaker radiation with longer wavelength (infrared)

• some of this passes through atmosphere unimpeded, but most is absorbed by GHGs and reemitted in all directions, including back to earth’s surface