Vegetation related climate uncertainty during the mid-Pleistocene warm period

Climate and vegetation are inherently intertwined through feedbacks that are still not fully understood. Reconstructing past climate-vegetation interactions is challenging because plants have undergone evolutionary, physiological, and ecological changes that cannot be inferred from the present day vegetation. Here we investigate a range of potential vegetation/climate states that could have existed 3 million years ago with the use of the BIOME4 vegetation model, pollen data, and iCESM1.3 mid-Pleistocene model simulations,. The BIOME4 model is widely used to reconstruct paleo vegetation although the plant phenology parameterization is based on modern day vegetation types. We explore the sensitivity of the model to the plant phenology parameterization and the space of possible vegetation distributions to find best fits to pollen data. With the use of iCESM1.3 we estimate the range of vegetation related climate uncertainties showing that this can cause local to global changes impacting e.g. arctic amplification and global circulations.