How does carbon dioxide affect PH?

Carbon dioxide (CO2) significantly influences the pH levels in both the ocean and human bodies through its role in the creation and maintenance of carbonic acid. Here's how it impacts pH in different environments:

In the Ocean

CO2 dissolves in ocean water forming carbonic acid, which slightly lowers the pH of the ocean, making it less alkaline. Without CO2, the ocean's pH would be around 11.3, similar to that of a drain cleaner like Drano, which is highly alkaline and hazardous to most forms of life. The presence of CO2 buffers the ocean's pH to about 8, which is conducive for marine life, supporting the existence of organisms like phytoplankton and coccolithophores which form the base of the marine food chain 1.

In the Human Body

In human physiology, CO2 is crucial for maintaining the acid-base balance within the body. It works primarily through the respiratory system, where an increase in CO2 levels leads to a decrease in blood pH (making it more acidic), and a decrease in CO2 makes the blood more alkaline. This balance is tightly regulated because significant deviations can affect enzyme function and the overall metabolic processes in the body. For example, in the context of exercise, excess hydrogen ions (a byproduct of anaerobic metabolism) are buffered by substances like bicarbonate, which are regulated in part by CO2 concentrations in the blood 2.

Additionally, changes in CO2 levels can influence how oxygen is transported and released in the body. Increased CO2 levels help in releasing oxygen from hemoglobin, which delivers oxygen to the tissues that need it. This interaction is crucial for cellular metabolism and maintaining energy levels in the body 3.

Overall, CO2 is essential for life, not only as a carbon source for photosynthesis in plants but also for regulating pH levels that are critical for sustaining various biological processes in the ocean and human health.