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Question 1

How has the carbon cycle impacted permafrost?

Answer 1

• Covers 22% of land surface
• Store of carbon
• Thaws due to increased temperatures
• Organic material decaying released carbon into atmosphere
• Positive feedback loop as more carbon means more thawing

Question 2

What are the effects of melting sea ice?

Answer 2

• Last 35 years sea ice reduced by 40%
  Positive feedback mechanism:
• Ice melts
• Heat absorbed and water increases - amplifies ice melting
• Habitat loss to algae - knock on effect to polar bears up the food chain

Question 3

Wildfire positive feedback loop

Answer 3

Wildfires are more likely in hotter and drier climates created by global warming, which release large quantities of CO₂ into atmosphere, which in turn then increases the warming effect.

Question 4

Ice positive feedback loop

Answer 4

Ice reflects radiation from the sun, reducing surface warming. As sea temperatures rise and ice melts, the warming effect is amplified as there is less ice to reflect the radiation. Further melting occurs and the process continues.

Question 5

permafrost positive feedback loop

Answer 5

Higher temperatures are thawing the permafrost releasing CO₂ and methane (which has 20 times the warming effect of CO₂), causing warming on a local and global scale.
The higher temperatures cause more permafrost to melt, causing further gas releases and further warming.

Question 6

Photosynthesis Negative feedback loop

Answer 6

Increased photosynthesis by plants and rising global temperatures allows vegetation to grow in new areas, e.g. where permafrost has melted.
New vegetation absorbs CO₂ from the atmosphere, decreasing the warming effect

Question 7

Phytoplankton negative feedback loop

Answer 7

Higher CO₂ levels causes phytoplankton to grow (as they feed off CO₂). CO₂ is taken in through photosynthesis and levels decrease as a result, causing phytoplankton to decrease.

Question 8

Cloud cover negative feedback loop

Answer 8

Higher temperatures causes phytoplankton to grow and photosynthesise quicker. Phytoplankton release substances (Dimethyl sulphide) that lead to the formation of clouds, meaning cloud cover increases. Radiation from the sun is therefore less able to reach the oceans, reducing temperatures. This therefore causes phytoplankton to grow less quickly and photosynthesise slower, reducing cloud cover.

Question 9

What is a negative feedback loop?

Answer 9

If an impact is such that the initial event is weakened or reduced

Question 10

What is a positive feedback loop?

Answer 10

If an impact is such that the initial event is enhanced

Question 11

How do the water and carbon feedback loops link together?

Answer 11

• Phytoplankton primary producers and important stores of carbon
• Release chemical substances called Dimethyl sulphide - causes formation of clouds over oceans
• Increase in phytoplankton due to increased temps leads to increase cloudiness and global cooling as it reduces solar radiation reaching Earth’s surface