Since the industrial revolution 30% of the anthropogenic CO has been absorbed by the oceans, resulting in ocean acidification, which is a threat to calcifying alga. As a result, there has been profound interest in these calcifying algae, boosted by their major role in the global carbon cycle. Globally, coccolithophores, particularly Emiliania huxleyi, are considered to be the most dominant calcifying algae, which blooms can even be seen from outer space. Calcifying algae create an exoskeleton from calcium carbonate platelets (coccoliths), providing ballast which enhances the organic and inorganic carbon flux to the deep sea. Organic carbon is formed by means of photosynthesis, where CO is fixed and converted into organic molecules, causing removal of CO from the seawater. Counterintuitively, the production of coccoliths leads to the release of CO in the seawater, due to removal of carbonate from the seawater, which reduces the alkalinity and causes acidification. Therefore, the ratio between particulate inorganic carbon (PIC) and particulate organic carbon (POC) is an important measure for the net release or uptake of CO. In short, the PIC:POC ratio is a key characteristic required to understand and predict the impact of climate change on the global ocean carbon cycle.