Editing IPCC:AR6/WGI/Chapter-10 (section)

=== Distillation of Regional Climate Information ===

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'''The process of distilling regional climate information from multiple lines of evidence can vary substantially from one case to another.''' Although methodologies for distillation have been established, in practice the process is conditioned by the sources available, the actors involved and the context, which depend heavily on the regions considered, and is framed by the question being addressed. To make the most appropriate decisions and responses to changing climate, it is necessary to consider all physically plausible outcomes from multiple lines of evidence, especially in the case when they are contrasting. {10.5, 10.6, Cross-Chapter Box 10.1, Cross-Chapter Box 10.3}

'''confidence in the distilled regional climate information is enhanced when there is agreement across multiple lines of evidence.''' For example, the apparent contradiction between the observed decrease in Indian monsoon rainfall over the second half of the 20th century and the projected long-term increase is explained by attribution of the trends to different forcings, with aerosols dominating recently and greenhouse gases in the future ( ''high confidence'' ). For the Mediterranean region, the agreement between different lines of evidence, such as observations, projections by regional and global models, and understanding of the underlying mechanisms, provides ''high confidence'' in summer warming that exceeds the global average. {10.5.3, 10.6, 10.6.3, 10.6.4, Cross-Chapter Box 10.3}

'''The outcome of distilling regional climate information can be limited by inconsistent or contradictory information.''' Initial observational analyses of the Cape Town drying showed a strong, post-1979 association between increasing greenhouse gases, changes in a key mode of variability (the Southern Annular Mode) and drought in the Cape Town region. However, not all global models show this association, and subsequent analysis extending farther back in time, when human influence was weaker, showed no strong association in observations between the Southern Annular Mode and Cape Town drought. Thus, despite the consistency among global-model future projections, there is ''medium confidence'' in a projected future drier climate for Cape Town. Likewise, the distillation process results in ''low confidence'' in the influence of Arctic warming on mid-latitude climate because of contrasting lines of evidence. {10.5.3, 10.6.2, Cross-Chapter Box 10.1, Cross-Chapter Box 10.3}

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