Introduction

This Technical Summary complements and expands the key findings of the Working Group II (WGII) contribution to the Sixth Assessment Report (AR6) presented in the Summary for Policymakers and covers literature accepted for publication by 1 September 2021. It provides technical understanding and is developed from the key findings of chapters and cross-chapter papers as presented in their Executive Summaries and integrates across them. The report builds on the WGII contribution to the Fifth Assessment Report (AR5) of the IPCC and the three Special Reports of the AR6 cycle providing new knowledge and updates. The three Special Reports are Global Warming of 1.5°C, an IPCC Special Report on the impacts of1.5°C above pre-industrial levels and related global greenhouse has emission pathways, in the content of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty; Climate Change and Land, an IPCC Special Report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems; and The Ocean and Cryosphere in a Changing Climate, Special Report of the Intergovernmental Panel on Climate Change. The WGII assessment integrates with the WGI (the Physical Science Basis) and WGIII (Mitigation of climate change) contributions as well as contributing to the Synthesis report.