Dr. Lennart de Nooijer’s research at NIOZ focuses on the underlying mechanisms of shell formation in foraminifera. These unicellular organisms produce a shell consisting of calcium carbonate for which they take up ions from the surrounding seawater. This process and the resulting chemical composition of their shells is influenced by the conditions (temperature, pH, etc.) in which these organisms live. Quantifying these relationships (for example Mg-incorporation as a function of seawater temperature) and application to fossil foraminifera allows reconstructing past changes in seawater conditions and thereby, past climates. Lennart collects and cultures foraminifera under a range of pCO2’s, salinities, etc to develop new tools to reconstruct the history of our earth. At the same time, he use these specimens to look at their biological controls on calcification. This will help to predict their response to current changes in ocean chemistry (like ongoing acidification and warming) and their ability to calcify in the near future.