Bathtub Analogy for CO2 Stock and Flow

Misconception: Reduced Emissions Rate vs. Atmospheric Stock

Causal Link Between CO2 Stock and Global Warming

A country successfully implements a policy that reduces its annual carbon dioxide (CO2) emissions from 10 billion tons to 5 billion tons. Assuming the planet's natural systems can absorb less than 5 billion tons of CO2 annually, what is the immediate effect of this policy on the total amount of CO2 in the atmosphere?

Atmospheric Gas Dynamics on a Fictional Planet

If humanity successfully reduces the annual rate of global carbon dioxide (CO2) emissions by 50%, but this new rate still exceeds the amount of CO2 that oceans and forests can absorb each year, the total amount of CO2 accumulated in the atmosphere will begin to decrease.

Analyzing the Impact of Emission Reductions

A simplified model of the global carbon cycle shows the following data for a three-year period:

• Year 1: Human-caused emissions = 40 gigatons; Natural absorption = 20 gigatons.
• Year 2: Human-caused emissions = 35 gigatons; Natural absorption = 20 gigatons.
• Year 3: Human-caused emissions = 30 gigatons; Natural absorption = 20 gigatons.

Based on this data, which statement accurately describes the change in the total stock of carbon dioxide in the atmosphere over this period?

Evaluating Climate Policy Statements

Consider the total amount of carbon dioxide in the atmosphere as being like the amount of water in a bathtub. Match each component of this system to its correct real-world equivalent.

Imagine the total amount of CO2 in the atmosphere is like the balance in a bank account. Annual human-caused emissions are like a yearly deposit, and the amount absorbed by natural systems is like a yearly withdrawal. If a new global policy successfully reduces the yearly deposit (emissions), but this new, smaller deposit is still larger than the yearly withdrawal (absorption), what will happen to the account balance (total atmospheric CO2) during that year?

A global initiative successfully reduces the yearly rate of carbon dioxide (CO2) emissions. However, this new, lower rate of emissions still exceeds the rate at which natural systems can remove the gas. Which of the following statements correctly describes the consequence of this change on the total amount of CO2 in the atmosphere?

An economic model tracks a planet's atmospheric gas levels. The table below shows the annual rate of a specific gas emitted by industrial activity and the annual rate of the same gas absorbed by the planet's natural systems over a 5-year period.

Based on this data, in which year did the total accumulated amount (stock) of this gas in the atmosphere first begin to decrease?