全球碳预算审计：探究2024-2025年版本变更

中文摘要 AI 辅助

全球碳预算（GCB）是碳循环领域的社区参考数据集，每年会重新发布。2025年版本对已发布序列进行了多项调整，我们将其与2017年起的先前版本进行了比较。在1959-2016年的共同样本中，2017-2024年各版本的GCB预算不平衡均值在±0.17 GtC/yr范围内，而2025年版本的该均值跃升至+0.61 GtC/yr，且是唯一的不平衡均值95%置信区间不包含零的版本。我们通过两种方式记录并探究这一变更：第一，开展无模型分析，将变更归因于一项新调整——该调整使已发布的陆地碳汇比其集合均值（基础模型的平均值）低0.40 GtC/yr，海洋碳汇则有一项方向相反的较小调整，且簿记集合中移除了一个模型；第二，考虑加入气候协变量的BHK2023动态统计GCB模型，对2017-2025年各GCB版本估计其参数，发现汇方程中大气浓度的系数在2025年版本中出现大幅反向偏移，与无模型分析结果一致，且预算方程在整个样本中存在持续漂移的不平衡。若2025年版本调整的预期效果是降低过去十年窗口内预算不平衡的均值，我们的结果表明，这是以整个样本的预算不平衡增加和数据记录不一致为代价的，我们认为，这些调整的成本超过了仅关注过去十年的收益，且不利于对完整GCB样本的统计分析。

英文摘要

The Global Carbon Budget (GCB), the community reference dataset for the carbon cycle, is reissued annually. The 2025 release introduces several adjustments to the published series that we compare with prior releases starting in 2017. On a common 1959-2016 sample, the mean of the GCB budget imbalance jumps from within +/-0.17 GtC/yr of zero for every vintage 2017-2024 to 0.61 GtC/yr in 2025, the only vintage whose 95% confidence interval for the imbalance mean excludes zero. The size of the imbalance changes much less: its mean absolute value rises from 0.61 to 0.76 GtC/yr. It is the mean, the quantity the budget identity constrains, that moves. We document and explore this shift in two ways. First, we conduct a model-free analysis, where we attribute the shift to a new adjustment that places the published land sink 0.40 GtC/yr below its ensemble mean (the average of the underlying models), a smaller adjustment in the ocean sink in the opposite direction, and a change in the composition of the bookkeeping ensemble. Second, we consider a dynamic statistical GCB model augmented with climate covariates. Its parameters are estimated for every GCB vintage 2017-2025. The coefficients of atmospheric concentrations in the sink equations shift in opposite directions on the 2025 issue, mirroring the model-free findings. A constant in the budget equation, statistically unnecessary in every vintage from 2017-2024, is required in 2025 and is estimated at -0.59 (0.09) GtC/yr. There is a persistent drifting imbalance across the entire sample in the budget equation. Each of the three adjustments is documented in the 2025 release and rests on evidence about the component it corrects. Their joint effect is a budget that closes over the last ten years and carries a mean imbalance of 0.61 GtC/yr over the full record. We argue that this cost to the full sample outweighs the gain on the last ten years.

发表机构

• Aarhus University（奥胡斯大学）
• Vrije Universiteit Amsterdam（阿姆斯特丹自由大学）

机构由 AI 辅助整理，请以论文原文为准。