Lecture 31

Question 1

What is causing the increase in atmospheric CO₂?

Answer 1

Primarily fossil fuel combustion

Question 2

What is the current CO₂ level in the atmosphere?

Answer 2

About 420 ppm

Question 3

How do we know CO₂ is from fossil fuels?

Answer 3

Decreasing 13C/12C ratio – fossil fuels are depleted in 13C

Question 4

What is the greenhouse effect?

Answer 4

GHGs like CO₂ and CH₄ trap heat and increase Earth’s temperature

Question 5

How does increased CO₂ affect plants?

Answer 5

Increases photosynthesis & nitrogen use efficiency, but may lower protein content

Question 6

What is ocean acidification?

Answer 6

CO₂ dissolves in water, forms carbonic acid, lowers pH

Question 7

Direct effects of ocean acidification?

Answer 7

Weakens calcium carbonate shells (e.g., oysters, corals, pteropods)

Question 8

Indirect effects of ocean acidification?

Answer 8

Alters food webs and feeding patterns across marine species

Question 9

One ocean-based solution to acidification?

Answer 9

Kelp farming – absorbs CO₂, raises local seawater pH

Question 10

What is FACE?

Answer 10

Free-Air CO₂ Enrichment – field studies testing CO₂ impacts on plants