SB62 IPCC Side Event - Informing Climate Action: Overshoot
- 1. S E V E N T H A S S E S S M E N T C Y C L E Overshoot Robert Vautard (WGI) & Oliver Geden (WGIII), with support from Bart van den Hurk (WGII)
- 2. • Overshoot in AR6 mainly a mitigation pathways story: exceeding a warming level and returning • AR6 SYR: exceedance of 1.5°C in 2030s, return by 2100 • Return to 1.5°C requires net- negative CO2 emissions + significant cuts in non-CO2 • Drastic emissions cuts 2019- 2030 (GHG: 43%, CO2: 48%) doesn‘t avoid >1.5°C but helps to limit overshoot (to 0.1°C) • In AR6, not so much attention on Earth System responses to overshoot trajectories, (ir)reversibility of impacts under overshoot or feasibility challenges of achieving net- negative CO2 emissions I P C C A R 6 S Y R , F I G U R E 3 . 5
- 3. S E V E N T H A S S E S S M E N T C Y C L E WGI Chapter 9 Scoping Meeting Background Info Chapter 9 assesses the Earth system response to pathways towards temperature stabilization, including overshoot pathways. Its objective is to provide policy-relevant information on global and regional Earth system responses to global net-zero and net-negative emissions, including the long term implications. It addresses constraints to stabilization and overshoot pathways through Earth system feedbacks, potential biophysical limits for large scale carbon dioxide removal, and responses to solar radiation modification. Due to its cross-cutting character, Chapter 9 is expected to be developed in close cooperation with WGII and WGIII. WGI Chapter 9: Earth system responses under pathways towards temperature stabilization, including overshoot pathways Executive Summary Frequently Asked Questions 1. Global and regional Earth system responses to pathways towards temperature stabilization, including to global net-zero, negative and net- negative emissions, and long-term implications 2. Pathway dependency of responses including in the context of overshoot and irreversible aspects 3. Bio-geophysical capacity and limits of carbon dioxide removal (CDR) methods 4. Global and regional Earth system responses to removals of carbon dioxide, methane or nitrous oxide 5. Global and regional Earth system responses to different global and regional solar radiation modification (SRM) methods, including consequences and uncertainties
- 4. S E V E N T H A S S E S S M E N T C Y C L E WGIII Outline Chapter 3 (Projected Futures) • Relationship between global temperature goals and mitigation action, including overshoot, relationship between gross emissions reductions, residual emissions, and negative emissions. Chapter 6 (Policies, Governance, Int. Cooperation) • Long-term policy, governance and international cooperation for climate action and net zero emissions and beyond. Chapter 15 (Carbon Dioxide Removal) • Effectiveness of CDR at different warming levels and timescales • The role of CDR strategies in net-zero and net-negative emissions futures, including levels of residual emissions achievable WGII Scoping Meeting Background Info mentions ‘overshoot’ 21 times (but OS not explicitly included in WGII outline) • Chapter 1 (Framing and Key Concepts) includes overshoot and what’s at stake for people and ecosystems • Chapter 2 (Vulnerabilities, Impacts and Risks) includes feedbacks, ir/reversibility of impacts under different adaptation/mitigation pathways (incl. overshoot) and risks of response measures like Carbon Dioxide Removal and Solar Radiation Modification • Chapter 4 (Adaptation) & Regional Chapters (7-13) includes feasibility of adaptation for a range of future scenarios (incl. risk of insufficient adaptation in case of overshoot)