Modeling past present and future climate induced vegetation changes in East Africa East Africa is a natural laboratory: Studying its unique geological and biological history can help us better inform our theories and models. Studying its present and future can help us protect its globally important biodiversity and ecosystem services. East African vegetation plays a central role in all these aspects and this dissertation aims to quantify its dynamics through computer simulations. Computer models help us recreate past settings forecast into the future or conduct simulation experiments that we cannot otherwise perform in the field. But before all that one needs to test their performance. The outputs that the model produced using the present day inputs agreed well with present day observations of East African vegetation. Next I simulated past vegetation for which we have fossil pollen data to compare. With computer models we can fill the gaps of knowledge between sites where we have fossil pollen data from and create a more complete picture of the past. Good level of agreement between model and pollen data ...