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Question 1

Positive feedback in water cycle

Answer 1

Increased evaporation of water vapour from oceans due to rising global temperatures.
Water vapour is a greenhouse gas. Therefore more water vapour means higher temperatures and more global warming. This warming will further enhance evaporation, producing more water vapour and so the positive feedback loop continues

Question 2

Positive feedback in the carbon cycle

Answer 2

More CO2 in atmosphere. This results in events such as global warming. This warms the tundra and it emits CO2 and methane into atmosphere. This results in more greenhouse gasses and so the cycle continues.

Question 3

Positive feedback in the carbon cycle

Answer 3

More CO2 means global temperatures rise. This warms the oceans and so they are less able to dissolve CO2. This releases CO2 into the atmosphere and so there is more greenhouse gas so the cycle continues.

Question 4

Positive feedback in the water cycle

Answer 4

Ice reflects radiation from the sun so less heat is absorbed by the surface. The extent of arctic ice is shrinking, exposing more water and so less reflection and more absorption of heat from the sun. This warms the water and it further melts and reduces ice coverage.

Question 5

Positive feedback in the carbon cycle

Answer 5

Higher temps have started to melt the permafrost. Organic matter trapped in the frozen ground act as an important carbon store. On melting, the organic matter in the permafrost start to decompose as oxygen is introduced. The bacteria involved in decomposition produce CO2 and Meghan as a waste product. These cases bubble to the surface and escape the atmosphere.

Question 6

Negative feedback in the carbon cycle

Answer 6

Higher temps have increased growing season for plants. This has increased the absorption of carbon from the atmosphere.

Question 7

Negative feedback in water/carbon cycle

Answer 7

Increased phytoplankton populations associated with warmer temperatures and more sunshine. Marine phytoplankton release a chemical called DMS that may promote the formation of clouds over the oceans. Therefore, more phytoplankton could lead to increased cloudiness and global cooling. Because clouds reduce the amount of solar radiation reaching the earths surface. (Less sunshine could reduce the amount of phytoplankton and reduce this effect)