Approaches and challenges in attributing climate change impacts

Addressing climate change requires knowledge of its impacts on both nature and people. This Review depicts current approaches to the attribution of climate change impacts and potential uses for this information. The discussion covers how impact attribution identifies the drivers of observed changes and events that form links in the causal chain from anthropogenic greenhouse gas emissions and other human-induced climate forcing factors to effects on natural and human systems mediated by changes in climate and weather. Various approaches are presented that use observations and/or model simulations to estimate how a world without climate change could have evolved. In addition, different societal uses of impact attribution results are discussed and how different study designs might support them. This Review also identifies persistent knowledge gaps that call for input from policy experts globally. For example, future tailored designs might enable the attribution of additional impacts and improve quantification of the role of climate change against other drivers, whereas increased transdisciplinary collaboration and organization might provide standardization that benefits data comparability and synthesis. Addressing the remaining challenges is expected to help the impact attribution community to produce targeted answers for well-framed questions that inform development, implementation and operationalization of climate policies.