Screener: The Carbon Budget

Part 1: Modeling Matter Conservation

A student claims that since carbon is “cycled,” the total amount of carbon in the atmosphere should never change.

Evaluate the Claim: Using the concept of reservoirs and fluxes, explain why the student is incorrect.
State your reasoning: (Space for student response)

Part 2: Interactions of Earth’s Spheres

Use the table below to identify the Source Sphere and the Sink Sphere for each carbon flux.

Flux Name	Source Sphere	Sink Sphere
Photosynthesis	Atmosphere	______
Shell Formation	Hydrosphere	______
Fossil Fuel Extraction	______	Atmosphere
Volcanic Outgassing	Geosphere	______

Part 3: Quantitative Reasoning

In a computer model of the carbon cycle:

Initial Atmosphere: 800 GtC
Flux IN (Volcanoes): 0.1 GtC/yr
Flux IN (Human Activity): 9.0 GtC/yr
Flux OUT (Oceans): 2.5 GtC/yr
Flux OUT (Biosphere): 3.0 GtC/yr

Calculate the Net Flux: show your work.
Predict: What will be the size of the Atmospheric Carbon reservoir after 10 years?

Part 4: Design Solution Evaluation

You are testing a “Deep Sea Carbon Injection” technology. It captures CO2 from the air and pumps it into the deep ocean geosphere.

Identify one Potential Feedback Loop: If the ocean becomes too acidic because of this injection, how might that affect the biosphere’s ability to act as a carbon sink in the future?

(Space for student response)