This section synthesises the observed impacts of changes in climate- related systems  on different natural, human and managed systems  and regions . To stay as specific as possible given the required level of aggregation, we decided in favour of a summary along specific prominent indicators such as 'crop yields' or 'areas burned by wildfires' instead of an assessment across broad categories such as 'food production' which could include a broad range of measures ranging from climate-induced changes in growing seasons to impacts on livestock and fisheries, etc., or 'wildfires' which could also cover impacts on the frequency, intensity, timing, or emissions and health impacts of wildfires. This decision for specificity certainly implies a decision against comprehensiveness. In addition, the level of specificity has to be adjusted given the literature basis which is quite broad regarding crop yields but still limited and less harmonised regarding indicators when it comes to, for example, conflicts. A broader discussion can be found in the sectoral or regional chapters that all cover 'observed impacts' individually. Section 16.2.1 provides key definitions, followed by recent advances in available methods and data for climate impact attribution , and the assessment of observed impacts of changes in climate related systems . It is important to note that the assessment is primarily based on peer-reviewed literature, that is, it is limited to the regions and phenomena for which such studies are available. So 'no assessment' in a certain region does not imply that the considered type of impact did not occur in this region.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report