Following the trenchant criticism of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report concerning the lack of transparency in integrated assessment models (IAMs), much attention has been given to addressing this issue in the preparation of the Sixth Assessment Report (AR6). The issue of IAM transparency has been an ongoing concern for approximately two decades regarding the cloaking of value‐laden assumptions and output uncertainties. Due to the opaque nature of IAMs, the credibility of modeling results and the associated policy recommendations are patently limited, with policymakers inevitably having reservations as to the robustness of modeling outcomes given the deficit of information regarding the underlying assumptions. In an attempt to address the issue of a lack of transparency concerning IAM usage by the IPCC, a database containing the climate mitigation scenario ensemble which underpinned the Special Report on Global Warming of 1.5°C was made publicly available, the IAMC 1.5°C Scenario Explorer database. Despite this database, the omission of critical model input data and accompanying supporting documentation from its content fails to fulfill its raison d'être, that is to say, to ensure reproducibility and transparency. If the issue of IAM transparency is not fully addressed in the upcoming AR6 with respect to the provision of IAM input data, accompanied by supporting documentation, then the IPCC will have failed to meet its own declared commitment for this assessment cycle.

中文翻译：

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透明，信任和综合评估模型：政府间气候变化专门委员会的道德考量

在政府间气候变化专门委员会（IPCC）第五次评估报告中对综合评估模型（IAM）缺乏透明度提出了强烈批评之后，在编写第六次评估报告（AR6）时，已经非常重视解决这一问题。 。IAM透明性问题一直困扰着近二十年来有关隐含高价值假设和产出不确定性的问题。由于IAM的不透明性，建模结果和相关政策建议的可信度受到专利限制，鉴于有关基础假设的信息不足，决策者不可避免地对建模结果的健壮性有所保留。为了解决IPCC使用IAM缺乏透明度的问题，IAMC 1.5°C方案浏览器数据库已公开发布，该数据库包含支持1.5°C的全球变暖特别报告的气候缓解方案集合。尽管有此数据库，但从其内容中忽略了关键模型输入数据和随附的支持文档仍无法实现raison d'être，即确保可重复性和透明性。如果在即将发布的AR6中，关于IAM输入数据的提供并没有附带支持文档，IAM透明度问题没有得到完全解决，那么IPCC将无法履行其对本评估周期的声明承诺。