Vegetation response to varying CO2 conditions during the Mid-Pliocene Warm Period.

The Mid-Pliocene Warm Period (mPWP) provides a valuable analog for near-future climate warming with an estimated global mean temperature  2.5–4°C higher than today and atmospheric CO₂ concentrations ranging from 360 to 420 ppm. Vegetation changes during the mPWP were significant, playing a crucial role in the climate through feedback mechanisms. Studying the climate-vegetation interactions provides insights into their strength, temporal dynamics, and their role in extreme events. We plan to investigate these interactions by examining vegetation changes under various climate scenarios, including distinct vegetation configurations. As a first step in this research, we will develop a set of vegetation scenarios from exploratory model runs which will then be used as boundary conditions in future runs—in combination with other varying conditions such as varying GHG levels, paleogeography, orbital configurations, and aerosol emissions— to incorporate vegetation dynamics in the mPWP experiments.

Here, we present preliminary results regarding the changes in spatial coverage of different vegetation during mPWP scenario runs and our proposed vegetation scenarios. The vegetation scenarios are developed from mPWP simulations with varying atmospheric CO₂ concentrations of 350 ppm, 400 ppm, and 490 ppm. These simulations were performed with the Community Earth System Model version 1.2, a fully coupled climate model, and Biome4, an offline equilibrium vegetation model. We will show the responses of paleo vegetation to climates under different CO₂ levels and quantify the stability of vegetation around the globe within the different scenarios. Based on these results, we will propose a set of vegetation scenarios for use in future studies.