As a result of global climate change marine phytoplankton has to cope with many changes in their environment. The most obvious is an increasing temperature of the oceans. As a result of the increased temperature the stratification in certain regions will increase leading to a shallowing of the euphotic zone. Therefore, the phytoplankton will be exposed to a higher light intensity. Furthermore, the increased stratification would inhibit the mixing of surface and deep water, which supplies new nutrients to the surface water that are available for phytoplanktonic growth. This in turn would lead to reduced primary production and export, and a change in the phytoplankton community structure. Coccolithophores are an abundant group of marine phytoplankton and important in the oceanic carbon cycle. They are calcifying organisms, which constitute the carbonate counter pump – part of the oceanic carbon cycle besides the biological and the physical carbon pump. Furthermore, their coccospheres contribute to increasing the sinking velocity of organic particles. Therefore it is important to know to what level coccolithophores will be affected by global climate change. Until this point research has focused on the most abundant coccolithophore Emiliania huxleyi. However this species plays only a minor role in the processes mentioned above as it has a small cell size. In my project I examine the growth of various coccolithophores under different light-, temperature- and nutrient conditions and will use these results to simulate the effect of climate change on coccolithophores in the global ocean biogeochemical model PlankTOM10.