[A-CG64] Projection and detection of global environmental change

2:45 PM - 3:00 PM JST(5:45 AM - 6:00 AM UTC)

[ACG64-05] Emergent constraint on the future global temperature and remaining carbon budget

*Irina Melnikova^1,2, Tokuta Yokohata¹, Hideo Shiogama¹ (1.National Institute for Environmental Studies, 2.Tsukuba University)

Keywords:

carbon budget,climate change,TCRE,CMIP

Reducing uncertainty in future temperature projections is crucial for understanding climate impacts of anthropogenic CO₂ emissions and for guiding effective climate policy. This remains a complex challenge, as uncertainty in temperature projections arises from both climate and carbon cycle feedbacks. Here, we introduce an observational constraint that integrates these feedbacks into emissions-driven simulations, reducing uncertainties in projected global temperature and effective Transient Climate Response to Cumulative CO₂ Emissions (eTCRE). Our approach lowers the projected mid-21st century eTCRE from 2.2 [1.3–3.1] to 1.9 [1.3–2.5] °C per 1000 GtC. It also reduces projected end-of-century global temperature from 4.6 [2.8–6.4] °C to 4.2 [2.9–5.4] °C and refines estimates of the remaining carbon budget since 2020 for limiting warming to 2 °C from 352.2 [2.1–702.3] to 458.9 [251.4–666.3] GtC under high-emission RCP8.5 / SSP5-8.5 scenarios. These refined projections provide critical insights for policymakers, enabling more effective mitigation strategies.