Vegetation pattern and terrestrial carbon variation in past warm and cold climates

Understanding the transition of biosphere‐atmosphere carbon exchange between glacial and interglacial climates can constrain uncertainties in its future projections. Using an individual‐based dynamic vegetation model, we simulate vegetation distribution and terrestrial carbon cycling in past cold and warm climates and elucidate the forcing effects of temperature, precipitation, atmospheric CO2 concentration (pCO2), and landmass. Results are consistent with proxy reconstructions and reveal that the vegetation extent is mainly determined by temperature anomalies, especially in a cold climate, while precipitation forcing effects on global‐scale vegetation patterns are marginal. The pCO2 change controls the global carbon balance with the fertilization effect of higher pCO2 linking to higher vegetation coverage, an enhanced terrestrial carbon sink, and increased terrestrial carbon storage. Our results indicate carbon transfer from ocean and permafrost/peat to the biosphere and atmosphere and highlight the importance of forest expansion as a driver of terrestrial ecosystem carbon stock from cold to warm climates.