Integrated assessment models (IAMs) connect trends in future socioeconomic and technological development with impacts on the environment, such as global climate change. They occupy a critical position at the global science-policy interface. IAMs and associated scenarios have come under intense scrutiny, with critiques addressing both methodological and substantive issues, such as land use, carbon dioxide removal and technology performance. Criticisms have also addressed the transparency of IAM methods and assumptions as well as the transparency of the Intergovernmental Panel on Climate Change (IPCC) assessment of IAMs. This paper, authored by the co-chairs of IPCC Working Group III and members of the Technical Support Unit, documents activities aiming to enhance the transparency of IAMs and their assessment. It includes a history of IPCC's approach to scenarios covering the formation of the Integrated Assessment Modeling Consortium (IAMC) in 2007 and the emergence of the approach by which IPCC facilitates the development of scenarios, but does not produce them itself. An IPCC Expert Meeting at the start of the current assessment cycle made transparency recommendations targeted at both the research community and IPCC. The community has taken steps to “open the black box” by moving toward open-source and web-publishing IAM documentation. IPCC has included an Annex to its next report focusing on scenarios and modeling methodologies. An open call for scenario data linked to the current IPCC report includes an expanded set of input and output variables. This paper ends with suggested criteria for measuring the success of these efforts to improve transparency.

中文翻译：

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政府间气候变化专门委员会：透明度和综合评估建模

综合评估模型 (IAM) 将未来社会经济和技术发展的趋势与对环境的影响（例如全球气候变化）联系起来。它们在全球科学政策界面中占据关键位置。IAM 和相关情景受到严格审查，批评涉及方法论和实质性问题，例如土地利用、二氧化碳去除和技术性能。批评还涉及 IAM 方法和假设的透明度以及政府间气候变化专门委员会 (IPCC) 对 IAM 评估的透明度。这份文件由 IPCC 第三工作组的联合主席和技术支持小组的成员撰写，记录了旨在提高 IAM 及其评估透明度的活动。它包括 IPCC 的历史' 情景方法涵盖了 2007 年综合评估建模联盟 (IAMC) 的成立以及 IPCC 促进情景开发但不自行生成情景的方法的出现。当前评估周期开始时的 IPCC 专家会议提出了针对研究界和 IPCC 的透明度建议。社区已采取措施通过转向开源和网络发布 IAM 文档来“打开黑匣子”。IPCC 在其下一份报告中包含了一个附件，重点是情景和建模方法。对链接到当前 IPCC 报告的情景数据的公开征集包括一组扩展的输入和输出变量。本文最后提出了衡量这些提高透明度的努力是否成功的建议标准。