The Mid-Pliocene Warm Period (ca. 3.264 to 3.025 Ma) provides a suitable test bed for sensitivity studies with enhanced CO2 concentration of 400 ppmv. With the Earth being a complex system, especially model data allows analyses of the interaction of different subsystems of the Earth’s climate, as done by the PlioMIP2. In this case the influence of temperature and precipitation on the growth of different plant types with adaptations in CO2 concentration as well as orography and ice sheets is analysed, and correlation is tested with the coefficient of determination. In difference to the pre-industrial configuration with 280 ppmv, the mid-Pliocene experiment of 400 ppmv gives a global warming of 3.20 °C with a shift of minima and maxima from -77 to - 67 °C and 43 to 49 °C. This, in addition to regional changes in precipitation, leads to a northward shift of treeline in Asia, North Africa and North America of up to 2200 km accompanied by a decrease of grass cover. Those, however, expand in regions like the Amazonian rainforest and Europe. Local analyses of Siberia and the Sahel Zone reveal mostly significant correlation of changes in plants and temperature, but not of changes in vegetation and precipitation.