TIPMIP-BIO: Towards a unified simulation protocol to assess potential tipping behavior in the biosphere and associated feedbacks and processes

The terrestrial biosphere plays a crucial role in regulating biogeochemical cycles, storing carbon, and providing essential ecosystem services, yet the land carbon sink remains a large source of uncertainty in future climate projections. Under the combined pressures of climate change, land use, pests, and fire, major biomes such as the Amazon and boreal forests face widespread degradation and may exhibit tipping behavior. The Tipping Points Modelling Intercomparison Project (TIPMIP) brings together the modelling community to develop unified simulation protocols for Earth System Models and standalone models, including Dynamic Global Vegetation Models. In this context, TIPMIP-BIO aims at running idealized experiments of climate overshoot and stabilizations scenarios, in order to assess climatic and deforestation thresholds that could trigger nonlinear biosphere responses. The framework provides opportunities to examine key processes and feedbacks, including CO₂ fertilization and physiological responses, and to explore emerging questions such as plant trait variability and the impact of compound climate events.