Lesson 12- What are the feedback loops within the water and carbon cycle?

Question 1

How does photosynthesis cause negative feedback?

Answer 1

Carbon Fertilisation:

1) More carbon in the atmosphere
2) Higher temperatures
3) More photosynthesis
4) Plants grow more and faster
5) Plants take in carbon from the atmosphere
6) Less carbon in the atmosphere which means that photosynthesis then reduces

Question 2

Will plants always photosynthesise more as atmospheric carbon increases?

Answer 2

• Scientists are researching whether carbon fertilisation is affected by other factors and peaks at a certain atmospheric CO₂ level.
• If true, then there will be a limit to how much CO₂ plants can continue to sequester
• It is suggested that carbon fertilisation is limited by water and nitrogen levels.
• If rainfall decreases as a result of climate change, then carbon fertilisation may decrease as a result, as water is required for photosynthesis.

Question 3

How do wildfires cause positive feedback?

Answer 3

1) More carbon in the atmosphere
2) Temperatures increase
3) More wildfires occur
4) Wildfires increase carbon in the atmosphere
5) Temperatures increase further
6) More wildfires again

Question 4

How does ice cause positive feedback?

Answer 4

1) Increased carbon in the atmosphere
2) Increased temperatures
3) Ice melt in the arctic
4) Less white surfaces more darker surfaces
5) Darker absorbs more heat
6) Increased temperatures
7) More ice melts

Question 5

How might ice cause negative feedback?

Answer 5

1) Increased carbon in the atmosphere
2) Increased temperatures
3) Ice melt in the arctic
4) More dark surfaces
5) Warmer temperatures
6) More evaporation
7) Increased cloud cover
8) Decreased temperatures

Question 6

How does permafrost melting cause negative feedback?

Answer 6

1) Increased carbon in the atmosphere
2) Temperatures increase
3) Permafrost melts
4) Decomposition of organic material occurs
5) Methane (CH4) released into the atmosphere (20x more powerful than CO2)
6) Increased carbon in the atmosphere
7) Temperatures increase again
8) More permafrost melts

Question 7

How big is the impact of permafrost melting?

Answer 7

• Currently, there are approximately 5 gigatons of methane in the atmosphere
• It is estimated that the Arctic permafrost holds hundreds of gigatons of methane
• Some of this extra carbon from methane can be absorbed and transferred by the oceans (33% of extra carbon has been absorbed by the oceans so far)
• As ice sheets melt, carbon storage increases, although this process cannot continue indefinitely, as eventually, the pH levels of the oceans will drop creating higher levels of ocean acidification

Question 8

How does phytoplankton cause negative feedback?

Answer 8

As temperatures warm at first there will be more phytoplankton as they like it warm this will lead to…..

Cloud cover and Phytoplankton:

1) Increased carbon in the atmosphere
2) Increased temperatures
3) Increased phytoplankton populations
4) Phytoplankton release substances that lead to the formation of clouds
5) More phytoplankton means cloud cover increases.
6) Clouds block sunlight
7) Less sunlight reaches oceans
8) Temperatures reduce
9) Phytoplankton populations reduce

Question 9

How does phytoplankton cause positive feedback?

Answer 9

Once temperatures get too hot phytoplankton don’t like it and cant survive, this will lead to…..

Phytoplankton and Ocean Stored Carbon

1) Increased carbon in the atmosphere
2) Increased temperatures
3) Temperatures get too hot for phytoplankton
4) Phytoplankton in oceans reduce
5) Less photosynthesis occurs
6) Carbon stored in oceans reduced
7) More carbon into the atmosphere
8) Temperatures increase further