Climate Bathtub - Ocean and Plant Absorption

Climate Bathtub - Ocean and Plant Absorption

Part of our web series "Climate Bathtub Model of Earth's Carbon Cycle"

In the "Climate Bathtub" model, increased carbon dioxide emissions from fossil fuel burning and other human activities can be represented as an increased flow into the tub from the faucet. As the amount of carbon dioxide in Earth's atmosphere has risen, some natural systems have begun to absorb some of the excess CO2, partially offsetting the human emissions. Specifically, the oceans and plants on land are absorbing some of the excess carbon dioxide in the atmosphere. In the "Climate Bathtub" model, the extra CO2 emissions from human activities are portrayed as a faster flow from the faucet. The ocean and plant absorption is portrayed as an increase in the flow out of the tub via the drain. It is important to note that the inflow from the faucet is still greater than the outflow via the drain; so the water level in the tub continues to rise, just a bit more slowly than would be the case if plants and the oceans were not absorbing some of the excess.

Compare the two animations below to see how the larger inflow from the faucet (left, representing increased human CO2 emissions) compares with an increased inflow and increased flow out of the drain (right, representing increased emissions and increased plant and ocean absorption). Notice how the water level still rises in the tub on the right, though somewhat more slowly.

As shown on another web page, increased emissions of CO2 to the atmosphere can be portrayed in the bathtub model as either a greater rate of inflow from a single faucet or as flow into the tub from multiple faucets. Likewise, more absorption by the oceans and plants can be shown either as a stronger flow out a single drain or as if some extra holes had been drilled into the tub, causing outflow from those leaks as well as from the drain.