Climate Bathtub Model

The Climate Bathtub Model is a great way of showing the different kinds of scenarios that we have and could experience related to global warming. In this analogy by John D. Sterman and Linda Booth Sweeney, the bathtub itself acts as the Earth’s atmosphere. The water flowing into the tub from the faucet, represents the carbon dioxide that is being added to the atmosphere, while the water leaving the drain represents the carbon dioxide leaving our atmosphere. Therefore the water left in the tub is the carbon dioxide that remains in our atmosphere. Through the different models you can see how increasing the inflow causes the amount of water in the tub, or carbon dioxide in our atmosphere, to increase quite fast. On the contrary, increasing the outflow would cause a rapid decrease in the carbon dioxide in our atmosphere.

By using this kind of model we can make predictions about the future by experimenting with the inflow and outflow speed, size, etc. Our goal would be to have the carbon dioxide that is being emitted into our atmosphere (from nature as well as human influence) equal the amount of carbon dioxide leaving the atmosphere: equilibrium. This model is able to show us that, as previously stated, an increase in the water going into the tub, carbon dioxide emitted into the atmosphere, that the tub will fill and eventually overflow.