SG4: How do the water & carbon cycles operate in contrasting locations? The Arctic Tundra

Question 1

What is tundra?

Answer 1

Tree less or barren landscape

Question 2

What are the characteristics of the Arctic tundra?

Answer 2

• Average temp wee below freezing throughout the year -12 degrees
• Short, cool summer/ long dark winters
• Permafrost occurs
• Periglacial area
• very low precipitation
• Found in the Northern hemisphere

Question 3

What is the normal climate in the Arctic Tundra?

Answer 3

• Climatic conditions are severe and become extreme with latitude
• 8-9 moths has a negative heat balance with average monthly temperatures below freezing.
• Warmer summer temps allows top soil (active layer) to thaw
• Long hours of daylight during the summer allows for short growing season
• Mean annual temp is low
• low mean precipitation of 20-350mm

Question 4

What are the characteristics of the AT soil?

Answer 4

• Active layer
• Permafrost
• Talik

Question 5

What is the active layer?

Answer 5

Ground that is seasonally frozen (is thicker in summer due to thawing of permafrost & thinner in winter when the ground refreezes.

Question 6

What is the permafrost?

Answer 6

The layer of soil that is permanently frozen all year round.

Question 7

What is the talik?

Answer 7

The unfrozen ground that lies below the permafrost and between the active layer and permafrost.

Question 8

What is low in the water cycle in the AT?

Answer 8

• transpiration
• evaporation
• groundwater store
• stores of moisture in the atmosphere

Question 9

Why is transpiration low?

Answer 9

The spareness of vegetation cover & short growing season means less transpiration can occur.

Question 10

Why is evaporation low?

Answer 10

This is because most of sun’s energy goes into the melting the snow so ground temp remain low & inhibit convection; also surface water & soil water are frozen for most of the year.

Question 11

Why is groundwater store low?

Answer 11

Permafrost is impermeable so acts as a barrier for infiltration, percolation, recharge & groundwater flow, therefore water cannot reach the soil below the surface.

Question 12

Why is the stores of moisture in the atmosphere low?

Answer 12

Due to low temp which reduces absolute humidity.

Question 13

Why is river discharge high during the Summer?

Answer 13

Due to high levels of melting & higher temperatures

Question 14

Why is river discharge low during the Winter?

Answer 14

Due to lots of freezing and lower temperatures.

Question 15

Why is surface discharge high in the summer?

Answer 15

Extensive wetlands, ponds and lakes provide a temporary storage of water due to the thawing of the active layer & permafrost.

Question 16

Why s surface discharge low in the winter?

Answer 16

The active layer freezes so any water on the ground is stores in solid ice.

Question 17

Why is the AT a carbon sink?

Answer 17

The permafrost acts a carbon sink because carbon is stored in the permafrost.

Question 18

Why is there a slow release of carbon?

Answer 18

Due to extreme cold temperatures, so little decomposition by bacteria and fungi.

Question 19

How could the permafrost act as a carbon source?

Answer 19

As permafrost thaws due to global warming, the frozen organic matter inside it thaws out, too, and begins to decay. Microbes in the soil eat the matter and produces large amount of co2 which bubbles up through the soil and making it way out to the atmosphere.

Question 20

What are the flows in the carbon cycle?

Answer 20

• Photosynthesis
• Plant respiration
• Decomposition
• Soil respiration

Question 21

Why is photosynthesis low?

Answer 21

Low temp results in sparse vegetation cover. The flux is also concentrated to the short summer when the plants grow rapidly in the long daylight hours.

Question 22

Why is plant respiration low?

Answer 22

The flux is concentrated in the summer when temperatures are warmer & tundra plants are growing so release co2 by respiration.

Question 23

Why is decomposition and soil respiration low?

Answer 23

The fluxes are higher in the summer when temp are warmer & tundra plant input litter to the soil but decomposition is slow due to still considerably low temperature.

Question 24

What are the stores in the carbon cycle?

Answer 24

• Biomass
• Atmosphere
• Soil

Question 25

Why is the biomass small?

Answer 25

Vegetation cover is sparse so there isn’t aren’t as many places to store the carbon.

Question 26

Why is the atmosphere store of carbon small?

Answer 26

Small fluxes of carbon e.g. low rates of plant respiration plus slow decomposition & slow soil respiration. Permafrost os a vast carbon sink.

Question 27

Why is the store of carbon in soil large?

Answer 27

Organic carbon becomes frozen in the permafrost and is locked away for 10s or 10,000 of years.

Question 28

What are the temperatures like in the Tundra?

Answer 28

• cold temperatures or most of the ear

- Precipitation levels are low between 50-350mm per year.

Question 29

What is permeability of the rock like in the AT?

Answer 29

Low because the permafrost acts as a barrier for infiltration and percolation and so there are fewer gaps for water/ fluids to seep through.

Question 30

What is the relief like in the AT?

Answer 30

Erosion and weathering over hundreds and millions of years has led to the flattening out of the land. Mainly this has been due to former ice sheets covering the area during the last ice age and eroding most of the land. Most of the land is flat.

Question 31

What are the winter changes in the AT?

Answer 31

There is minimal chance of photosynthesis and plant growth. Water is also frozen which is required for growth.

Question 32

What are the summer changes in the AT?

Answer 32

Highest levels of co2 removal from the atmosphere into vegetation of the AT around mid summer. Also, some carbon is lost to the atmosphere because the veg is dying back and decomposition.

Question 33

What are the challenges of exploiting gas and oil in the north slope of Alaska?

Answer 33

• 24hr darkness in winter
• Oil spillages
• Possible causing the cult go Alaska to flood (tsunami)
• Permafrost is hard to build on
• In an earthquake zone
• Temperatures could drop to as low as -40 degrees.

Question 34

How does human activity in the AT affect the water cycle?

Answer 34

• Thaws the permafrost = more run-off and river discharge
• More surface stores = more evaporation
• Mining for sand and gravel = artificial lakes created
• Natural drainage disrupted by infrastructure e.g. buildings and roads
• wATER EXTRACTION FOR INDUSTRIAL USE

Question 35

How does human activity affect the carbon cycle in the AT?

Answer 35

• Thaws the permafrost, increasingly the microbial activity allows more decomposition so more co2 and CH4 emissions
• Gas flaring & oil spillage releases co2
• Less veg means less photosynthesis and a smaller biomass store.

Question 36

What are the management strategies used to moderate the impacts of the oil and gas industry?

Answer 36

• Roads and buildings on gravel pads
• Building elevated on piles
• TAPS on elevated & refrigerated piles

Question 37

Roads and buildings on gravel pads?

Answer 37

Larger structures built on aggregate pads. These are layers of coarse and gravel 1-2m deep.
Reduces heat transfer from house to the ground.

Question 38

Buildings elevated on piles?

Answer 38

Building houses on stilts or adjusting;e legs. Lengthten the legs as the active layer thaws in summer or if the ground expands. Building on stilts means that buildings are raised so heat from the building cannot melt the permafrost. E.g. BP Operations Centre in Prudhoe Bay Alaska.

Question 39

TAPS on elevated & refrigerated piles

Answer 39

Oil is pumped through the pipeline at 80 degrees to keep it flowing. To prevent the permafrost from thawing, TAPs is built on stilts so it is above ground has an insulated coating which is 10cm thick surrounding the pipe.

Question 40

What is the impact of long term global climate change on the AT?

Answer 40

Global temperatures are increasing and the effect of climate change on the carbon cycle in the AT is currently unknown. it could lead to loss of carbon from the permafrost if the Tundra thawed, which would make the landscape a carbon source.

Question 41

What is the evidence we are not at the tipping point?

Answer 41

Research from arctic long term ecological research project looked at Toolik Lake, Alaska’s North Slope 20 year survey started in 1989 and greenhouses were placed over small areas of permafrost to see whether climate change will lead to more carbon being released from the permafrost as it thaws. It didn’t.

Question 42

What is the evidence we are at the tipping point?

Answer 42

He says if the temperatures rise 1.5 degrees above pre industrial evils then we would see more permafrost thaw. global temperatures have increased by 0.8 degrees since the late 1800s, so he says we would soo. reach the ‘tipping point’.