Abstract:

Although climate change is a global phenomenon, its manifestations and consequences are different in different regions, and therefore climate information on spatial scales ranging from sub-continental to local is important for the impact and risk assessments of climate change. To respond to this, the WGI report of IPCC AR6 Chapter 10 assess how to link the global to regional climate change. Regional climate change is the result of the interplay between regional responses to both natural forcings and human influence, responses to large-scale climate phenomena characterizing internal variability, and processes and feedbacks of a regional nature. This chapter emphasized how to distill regional climate information from multiple observational datasets, ensembles of different model types, process understanding, expert judgement and indigenous knowledge. The distillation attribute multi-decadal regional trends to the interplay between external forcing and internal variability. Human influence has been a major driver of regional mean temperature change since 1950 in many sub-continental regions of the world. The choice of the reference period and signal-to-noise threshold is important to robustly assess the future emergence of anthropogenic signals, as well as past emergence results. Human influence has contributed to multi-decadal mean precipitation changes in several regions, internal variability can delay emergence of the anthropogenic signal in long-term precipitation changes in many land regions. Distilling regional climate information from multiple lines of evidence will increase the fitness usefulness and relevance for decision-making.

Key words: Regional-scale information, Climate change, Distillation