Carbon Cycling & Earth-System Feedbacks — Drills · Grade 9 Science

Chapter: Oceans, Carbon & Climate

What these drills covers

By the end of Carbon Cycling & Earth-System Feedbacks you should be able to:

8 questions, written answer, numeric and multiple choice, each with a worked explanation.

Vocabulary used: reservoir, flux, feedback.

Problem 1

Describe the ice–albedo feedback.
Answer and explanation

Warming melts reflective ice, exposing darker surfaces that absorb more sunlight and can increase warming.

Problem 2

A reservoir begins at 100 units and gains net 2 units/year for 5 years. Find final storage.
Answer and explanation

110 units

100 + 2 × 5 = 110.

Problem 3

A positive feedback in a system
  1. always improves it
  2. amplifies the original change
  3. opposes the original change
  4. has no effect
Answer and explanation

amplifies the original change

Positive means reinforcing, not beneficial.

Problem 4

Melting sea ice exposing darker ocean is an example of
  1. negative feedback
  2. positive feedback
  3. no feedback
  4. a carbon sink
Answer and explanation

positive feedback

Darker water absorbs more energy, causing more melting — the change reinforces itself.

Problem 5

The ocean acts as a carbon sink because it
  1. releases carbon dioxide only
  2. absorbs more carbon dioxide than it releases
  3. has no carbon
  4. is salty
Answer and explanation

absorbs more carbon dioxide than it releases

It takes up a substantial share of emitted carbon dioxide, which also acidifies it.

Problem 6

Of 10 units of carbon emitted, 3 are taken up by the ocean and 2 by land plants. How many units remain in the atmosphere?
Answer and explanation

5 units

10 − 3 − 2 = 5 units stay airborne.

Problem 7

Explain why ocean uptake of carbon dioxide is not a solution without a cost.
Answer and explanation

Dissolved carbon dioxide forms a weak acid, lowering ocean pH. That makes it harder for corals, shellfish and some plankton to build calcium carbonate structures, affecting food webs. The uptake slows atmospheric warming while transferring the problem to ocean chemistry, so it reduces one harm by creating another rather than removing the cause.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Distinguish a carbon source from a carbon sink, and give one example that can be either.
Answer and explanation

A source releases more carbon than it absorbs; a sink absorbs more than it releases. A forest can be either: a growing forest takes up carbon and acts as a sink, while a burning or decaying one releases it and acts as a source. Which it is depends on the balance of the fluxes at that time, not on the kind of thing it is.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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