Climate Change and Ocean Acidification

Two problems, one solution

R.D.Schuiling, Institute of Geosciences, Utrecht

Abstract.

Two major problems, both caused by rising CO₂ levels in the atmosphere threaten human society, namely climate change and ocean acidification. Whereas the first is widely known and internationally discussed, the second is hardly known outside a small group of experts, although its effect may in the end overshadow the effects of climate change.

In geological history the CO₂ level of the atmosphere was controlled mainly by the weathering of basic silicates, turning the greenhouse gas CO₂ into the bicarbonate ion in solution. These bicarbonate solutions were then carried by rivers to the sea where they formed limestones and dolomites, the ultimate stable storage for CO₂. At the same time these weathering solutions added alkalinity to the sea. Marine life in all its forms has adapted to the imposed levels of pH and CO₂ pressure. There is disturbing evidence that the rapid rise of CO₂ levels, and the related drop in pH of the oceans are already negatively affecting many marine life forms, either directly or by the disturbance of their food web. It is proposed here to enhance the weathering process on a global scale, in order to remove CO₂ from the atmosphere and the oceans, and restore the optimal pH in the oceans for marine organisms.