Ocean Acidification: The Newest Threat to the Global Environment

Abstract

Ocean acidification is the newest global environmental threat confronting the earth. It is the consequence of the same anthropogenic excess that is responsible for global warming—release of much more CO₂ at much faster rates, minute after minute, than the earth's capability to assimilate. Considering that oceans cover almost 70% of the earth's surface, any upset in the balance of forces in the oceans due to anthropogenic CO₂ emissions has, potentially, much more massive consequences than the impacts scientists are witnessing on the rest 30% of the earth. Ocean acidification is the name given to the lowering of ocean pH that is beginning to occur because the oceans are being forced to absorb CO₂ at a much faster rate during the last few decades than it has been over the previous thousands of years. The term does not imply that the oceans have actually become acidic, or will become acidic in the near future; it signifies a shift of ocean pH toward less alkaline levels. This shift has already threatened coral reefs and calcifying organisms. The latest forecast based on the most sophisticated models and the most authentic field data indicate that the adverse impact may become precipitous in the much more immediate future than was forecast previously. Ocean acidification has also come to be called the other CO₂ problem. Oceans are also absorbing large quantities of two more acid-forming gases being released at unprecedented rates into atmosphere—SO_x and NO_x. Thus far, on a global scale, their impact has been relatively minor; less than 3% of the impact of CO₂, but is expected to grow in magnitude as the emissions continue to increase. Moreover, the impact is likely to be much stronger in coastal regions, with serious portents for humankind.

KEY WORDS:

• aragonite saturation
• calcification
• corals
• climate change, ocean acidification

ACKNOWLEDGMENTS

The authors thank the Ministry of Water Resources, Government of India, New Delhi for supporting an R&D project.