Abstract

Land-based carbon removal strategies, such as re/afforestation and bioenergy with carbon capture and storage (BECCS), are increasingly recognized in future Shared Socioeconomic Pathways, which aim to limit global warming to below 2 °C by the end of the 21st century. Accurate assessments are needed of the climate and carbon outcomes of large-scale projected initiatives to expand bioenergy crops, as well as comparisons of their impacts with other land-based mitigation strategies, such as reforestation and afforestation. However, most of the current assessments have focused on relatively small domains or have ignored crucial carbon-water-nitrogen interactions. In addition, existing assessments of re/afforestation and BECCS either focus on the effectiveness of carbon removal or biophysically-driven climate change impacts. Given that carbon and climate outcomes can diverge, a consensus accounting of the two effects is needed. By using an integrated multisector and multiscale human-Earth system modeling framework, I evaluate the biogeochemical and biogeophysical implications of two alternative land-based mitigation scenarios that aim to achieve the same end-of-the-century radiative forcing. The findings highlight the need for strategic land use planning to identify suitable regions for bioenergy expansion and re/afforestation, thereby improving the likelihood of achieving intended climate mitigation outcomes. Accurate representation of tropical ecosystem processes is crucial for enhancing our understanding and prediction of their impacts on Earth system dynamics in the context of climate change. The performance of land surface models in tropical regions has been significantly improved, which has important implications for understanding key physical processes that regulate future Earth system dynamics. These advances are also critical for the development of next-generation weather and climate models for tropical regions.