Caldeira Lab Research:Ocean acidification and ocean carbon cycle

Carbon emissions and acidification

Richard E. Zeebe, James C. Zachos, Ken Caldeira

Although the public generally thinks of rising temperatures as the sole effect of increased CO2 concentration, it can also have an acidifying effect on the ocean. Uptake of CO2 by oceans slows the rise of atmospheric concentration, but it could eventually lower the water's pH levels by amounts that are highly dangerous to marine life.

Zeebe, RE; Zachos, JC; Caldeira, K; Tyrrell, T. Oceans - Carbon emissions and acidification, Science 321 (5885):51-52, DOI: 10.1126/science.1159124.

Carbon emissions and their effect on pH: Maximum pH changes predicted by the model graphed against pH and time. A decrease in pH of 0.75 corresponds to a drop in acidity that could be very dangerous for marine life.


Much of the scientific and public focus on anthropogenic carbon dioxide (CO2) emissions has been on climate impacts. Emission targets have been suggested based primarily on arguments for preventing climate from shifting significantly from its preindustrial state. However, recent studies underline a second major impact of carbon emissions: ocean acidification. Over the past 200 years, the oceans have taken up ~40% of the anthropogenic CO2 emissions. This uptake slows the rise in atmospheric CO2 considerably, thus alleviating climate change caused by anthropogenic greenhouse gas emissions. But it also alters ocean chemistry, with potentially serious consequences for marine life (1).