OCR A Level ELSS - 8 OCR A Level ELSS 4.2 Arctic Tundra_North Slope CASE STUDY

Question 1

Where is the Arctic Tundra?

Answer 1

an area that extends from where the boreal forests end to the edge of the Arctic Ocean

Question 2

What are the main characteristics of the Arctic Tundra?

Answer 2

1. It is a vast, relatively flat, treeless and marshy region, usually with permanently frozen subsoil.​ 2. Low biodiversity with only a few dwarf species of plants.

Question 3

What temperatures does the Arctic Tundra experience?

Answer 3

Temperatures fluctuate from 4°C in summer to below -40°C in winter.

Question 4

Why does the Arctic Tundra experience such a cold climate?

Answer 4

For several weeks in winter, the sun remains below the horizon and temperatures can drop below -40oC.

Question 5

What is the growing season like in the Arctic Tundra?

Answer 5

It is very short But, there are long hours of daylight in the summer months

Question 6

What are the characteristics of Precipitation in the Arctic Tundra?

Answer 6

Low Annual precipitation of between 50-350mm. It mainly falls as rain in Summer But in Winter falls as snow.

Question 7

Why are there such low amounts of precipitation in the Arctic Tundra?

Answer 7

1. Atmosphere stores very small amounts of water vapour because low temperatures reduce absolute humidity (the amount of water the air can hold) 2. Low rates of transpiration as vegetation is parse 3. Low rates of evaporation, as most of suns energy is spent melting the ice.

Question 8

What are the characteristics of soil moisture in the Arctic Tundra?

Answer 8

Soil moisture is usually frozen but thaws in the summer months River flow is low as water remains frozen except in Summer, melting and thawing of permafrost in spring and summer increases river flow Active layer remains boggy as no water can penetrate the permafrost

Question 9

What are the characteristics of groundwater in the Arctic Tundra?

Answer 9

Groundwater remains frozen and permafrost acts as a barrier

Question 10

What are the characteristics of river flow in the Arctic Tundra?

Answer 10

River flow is low as water remains frozen except in Summer, melting and thawing of permafrost in spring and summer increases river flow

Question 11

What are the characteristics of the active layer in the Arctic Tundra?

Answer 11

Active layer is frozen in winter but during spring and summer the uppermost parts of the active layer melt and so remain very waterlogged and boggy as no water can penetrate the permafrost below. This leads to extensive wetlands and a sharp increase in river flow during the spring and summer months.

Question 12

What are the characteristics of evaporation in the Arctic Tundra?

Answer 12

Low rates of evaporation​ Most of the sun’s energy is expended (used) in melting snow so ground temperatures remain low​

Question 13

What are the characteristics of transpiration in the Arctic Tundra?

Answer 13

Limited transpiration because of the sparse vegetation and short growing season

Question 14

What effect does permafrost in the Arctic Tundra have on the water cycle in the ground and soil?

Answer 14

Permafrost is impermeable, therefore it acts as a barrier to infiltration, percolation, recharge and groundwater flow​ Consequently there is limited groundwater and soil moisture stores

Question 15

What are the Seasonal changes in stores and flows of water in the Arctic Tundra?

Answer 15

Average temperatures are below freezing for majority of year so water is stored as ground ice in permafrost layer During summer shall active layer thaws and liquid water flows on the surface, forming many pools of water and shallow lakes due to poor drainage water cannot infiltrate the permafrost

Question 16

What are the characteristics of Evapotranspiration in the Arctic Tundra?

Answer 16

In winter sub-zero temperatures prevent evapotranspiration from occurring In summer some evapotranspiration occurs from standing water in saturated soils and vegetation Low humidity throughout and precipitation is sparse

Question 17

What are the characteristics of ground and soil Permeability in the Arctic Tundra?

Answer 17

Permeability is low due to permafrost and crystalline rocks which dominate the the tundra in Sub-Canada and Arctic

Question 18

What is Drainage like in the Arctic Tundra?

Answer 18

Bad drainage due ti permafrost Minimal relief and glacial deposits impede drainage and mean soil waterlogs in summer months. This leads to extensive Wetlands in the Arctic Tundra.

Question 19

What effect do low temperatures in the Arctic Tundra have on the water cycle?

Answer 19

1. Because Temperatures are well below freezing for most of the year water is stored as ground ice in the permafrost layer​ 2. During the short summer, the shallow active layer (top 1m) thaws and liquid water flows on the surface.​ 3. Because permafrost is impermeable (water cannot infiltrate) drainage is poor.​ 4. In winter there is no evapotranspiration due to sub-zero temperatures​ 5. In summer some evapotranspiration occurs from standing water, saturated soils and vegetation.​ 6. Humidity is low all year round and precipitation is sparse

Question 20

What is the Relief like in the Arctic Tundra?

Answer 20

The landscape is relatively flat (gently undulating) as a result of hundreds of millions of years of erosion and weathering​. ​ The myriad (very many) and chaotic nature of glacial deposits impede drainage and contribute to water-logging during the summer

Question 21

How much carbon does Permafrost contain?

Answer 21

14% of worlds carbon

Question 22

Carbon Cycle in Tundra

Answer 22

Permafrost is a massive carbon sink 1600 gigaton per year. In summer majority of carbon is produced as active layer thaws plants grow rapidly in summer months together with long day light hours P.S is more effective, Carbon rich waste gets put into the soil by vegetation In Winter unfrozen soil and water in the permafrost act as carbon sources of methane and CO2, snow may also insulate dead organic matter allowing decomposition to occur at very slow rates

Question 23

What is the Net Primary Productivity in the Arctic Tundra?

Answer 23

less than 200 grams/m2/yr

Question 24

What is the rate of biomass in the Arctic Tundra?

Answer 24

Between 4-29 tonnes/ha

Question 25

Which stores more carbon in the Arctic Tundra, soils or above-ground biomass?

Answer 25

Tundra soils store 5x more carbon than the amount of carbon stored in the above-ground biomass.

Question 26

Is the Arctic Tundra a carbon a source or store?

Answer 26

The Arctic Tundra is currently a Carbon Store. This is because not much CO2 is produced into atmosphere. However as global warming increases and global temperatures rise, large Ice caps and permafrost melt, these contain large quantities of methane and once melted release huge masses of methane into the atmosphere leading to a negative feedback loop. However, this needs to be balanced with the fact that a warmer climate results in more vegetation, resulting in a higher uptake of atmospheric CO2 as a result of photosynthesis, which may reducing the impact.

Question 27

What is Carbon mainly stored as in the Arctic Tundra?

Answer 27

Mainly stored as partly decomposed plant remains in the permafrost. Most of this Carbon has been locked up for the past 500,000 years

Question 28

What are the Physical Factors affecting the stores and flows of Carbon in the Arctic Tundra?

Answer 28

1. Low temperature and unavailability of liquid water means there is limited plant growth and thus the total carbon store of biomass is small 2. Photosynthesis is low as vegetation is low as growing seasons only last a couple of months 3. Low temperatures and waterlogged grounds mean slow rates of decomposition and respiration meaning low rates of CO2 into atmosphere 4. Impermeability of permafrost, rocks and porosity means they have little influence on the water and carbon cycle

Question 29

What is the impact of Oil and Gas exploration and production in Alaska on the Carbon cycle in the Arctic Tundra?

Answer 29

Oil and Gas exploration and production has had significant impacts on the Carbon cycle in the Arctic Tundra. 1. Permafrost melting release CO2 and Methane, On North Slope estimated CO2 losses vary from 7-40 million tonnes a year with methane losses at 24,000-114,000 tonnes a year 2. Gas Flaring and Oil spillage input CO2 into atmosphere 3. Destruction of vegetation for infrastructure reduces amount of Photosynthesis occurring and therefore uptake of CO2 decreases, and vegetation grows too slowly to recover 4. Thawing of Soil increases rates of decomposition and emissions of CO2

Question 30

Where is there significant oil and gas exploration in Alaska?

Answer 30

An area called ‘North Slope’ which is between Brooks Range in the South and the Arctic Ocean in the North.

Question 31

What are the 3 main ways that oil and gas infrastructure cause localised melting of permafrost in the Arctic Tundra?

Answer 31

1. Infrastructure diffuses heat directly to the environment​ 2. Dust deposition along roadsides creates darker road surfaces, increasing the absorption of sunlight.​ 3. Removal of vegetation cover, which naturally insulates the permafrost.

Question 32

How does localised melting of the permafrost impact the water cycle in the Arctic Tundra?

Answer 32

The increased melting increases the amount of run-off and river discharge making flooding more likely.​ As a result of this increased surface water there is an increase in evaporation during the summer months.

Question 33

What is the Impact of Oil Exploration and Production on the Water cycle in the Arctic Tundra?

Answer 33

Oil and Gas exploration and production has had significant impacts on the Water cycle in the Arctic Tundra.

1. Melting of permafrost and snow increases surface run-off and river discharge increasing chance of flooding
2. In Summer, water stores such as lakes become more extensive increasing rates of evaporation
3. Strip mining of sand and gravel aggregates for construction creates artificial lakes which disrupt drainage and expose permafrost to further melting
4. Drainage networks are disrupted by road construction and oil operations
5. Water from creeks and river used for the industry and for construction of ice road reduce run off

Question 34

What is the impact of oil and gas exploration and production in North Slope on the permafrost in the Arctic Tundra?

Answer 34

It is estimated that between 7-40 million tonnes/year of CO2 is released from permafrost melting​ and between 24-114 thousand tonnes/year of CH4 from permafrost melting

Question 35

What is the impact of oil and gas exploration and production in North Slope on the vegetation and photosynthesis in the Arctic Tundra?

Answer 35

Destruction or degrading of tundra vegetation through building of oil and gas infrastructure reduces photosynthesis and the uptake of CO2. This issue is exacerbated (made worse) by the slow-growing nature of tundra vegetation which means that regeneration and recovery is very slow.

Question 36

What Strategies have been put in place to reduce the impact of oil and gas exploration in Alaska on the water and carbon cycles in the Arctic Tundra?

Answer 36

1. Insulated Ice and gravel pads. This helps to reduce permafrost from melting.
2. Building pipelines on elevated stilts. This provides insulation from heat-generating buildings and so reduces permafrost from melting.
3. Drilling laterally beyond drilling platforms. This means fewer drilling rigs need to be constructed. Consequently there is less construction (access roads, production facilities etc.) and so vegetation and permafrost is impacted less.
4. Better Technology through Remote Sensing. These help to detect oil and gas sites more accurately before drilling and so fewer exploration wells are needed. This reduces the impact on vegetation and permafrost.
5. Refrigerated Supports. These are used on the Trans-Alaskan Pipeline (TAP), which help to stabilise the temperature of the permafrost.