Speaker: Alexander Ruane (NASA/GISS)
Topic: Assessing regional changes in multiple climatic impact-drivers to inform regional adaptation and risk management -- IPCC AR6 WGI Chapter 12

The Intergovernmental Panel on Climate Change (IPCC) released its latest Working Group I Report on August 9th, 2021, providing an assessment of Physical Climate Science with inputs from 100s of international scientists and an open review process that incorporated more than 14000 review comments. In this talk I will summarize the main findings of the report relating to regional climate information that informs impact and risk planning, drawing largely from WGI Chapter 12 (for which I served as Coordinating Lead Author). A key element of this report is the introduction of a Climatic Impact-Driver (CID) framework that helps focus planning on climatic changes connected to responses in society and ecosystems, helping stakeholders identify which indices and thresholds are important and then evaluating changes across time, space, and scenario. Chapter 12 develops an inventory of 33 climatic impact-drivers, identifies important CIDs and related indices for each sector (e.g., agriculture, water resources, cities, ecosystems, health), assesses CID changes for a comprehensive set of 51 land regions, and evaluates the general response of each CID to global warming levels. The process of CID assessment is built around multiple lines of evidence connecting physical understanding, observed trends, attribution of human influence on changes, and projections for the future. Together, this information responds to the United Nations Framework Convention on Climate Change (UNFCCC) policymakers’ requests for more actionable climate information to inform adaptation, mitigation and risk planning. This focus on impact- and risk-relevant regional changes in mean and extreme conditions also sheds light on model uncertainty across CMIP6 (which includes GISS Model-E simulations) and downscaling efforts like CORDEX-CORE and ISIMIP.