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Concept of risk and visualization of its changes in the reports of the Intergovernmental Panel on Climate Change.
Decision making in the field of limiting anthropogenic impacts on the climate system, including climate itself, requires the estimates of consequences. The assessment of the confidence of estimates is important for the reliable justification of the decisions, in particular, for the risk analysis. Such an approach was developed in the scientific reports of the Intergovernmental Panel on Climate Change (IPCC), in contributions of its Working Group II ‘Impacts, adaptation and vulnerability’. The paper presents the evolution of the risk concept in the IPCC scientific reports and current understanding of risk in the latest special reports of 2018-2019. This understanding is based on the fact that risk arises from the interaction of three factors: the presence of a climate related hazard, the exposure of an affected object to the hazard and object vulnerability. The construction of ‘burning ember diagrams’, BE-diagrams, is used in the IPCC reports as the main approach for the aggregation and visualization of information on climate related changes in risk levels for natural and socio-economic systems, as well as for human health. However, the BE-diagrams presented in publications demonstrate some imperfections, and the procedure for constructing BE-diagrams in the IPCC reports is not sufficiently formalized. BE-diagrams are based on analyzing and summarizing data and information of two kinds: (a) field observations’ results, experimental and modelling data available from the scientific literature; (b) IPCC expert judgements. However, the IPCC published no clear procedure that would include the sequence of steps, starting from (a) and (b), required to assess risks and to build corresponding BE-diagrams. The paper provides an example of such a procedure, i.e. an algorithm for the construction of a visual image summarizing the assessment of adverse effects of climate warming on an agricultural crop, specifically, spring wheat. The demonstrated approach to the construction of BE-diagrams can be generalized and used in the development of BE-diagrams for the other elements of natural or socio-economic systems affected by climate change. To ensure the transparency of assessments of climate change impacts performed with BE-diagrams and to allow users to repeat the assessments, a special IPCC Guidance note on this issue is needed.