Results from the fully and biogeochemically coupled simulations in which CO₂ increases at a rate of 1 % yr^−1 (1pctCO2) from its preindustrial value are analyzed to quantify the magnitude of carbon–concentration and carbon–climate feedback parameters which measure the response of ocean and terrestrial carbon pools to changes in atmospheric CO₂ concentration and the resulting change in global climate, respectively. The results are based on 11 comprehensive Earth system models from the most recent (sixth) Coupled Model Intercomparison Project (CMIP6) and compared with eight models from the fifth CMIP (CMIP5). The strength of the carbon–concentration feedback is of comparable magnitudes over land (mean ± standard deviation = 0.97 ± 0.40 PgC ppm^−1) and ocean (0.79 ± 0.07 PgC ppm^−1), while the carbon–climate feedback over land (−45.1 ± 50.6 PgC ^∘C^−1) is about 3 times larger than over ocean (−17.2 ± 5.0 PgC ^∘C^−1). The strength of both feedbacks is an order of magnitude more uncertain over land than over ocean as has been seen in existing studies. These values and their spread from 11 CMIP6 models have not changed significantly compared to CMIP5 models. The absolute values of feedback parameters are lower for land with models that include a representation of nitrogen cycle. The transient climate response to cumulative emissions (TCRE) from the 11 CMIP6 models considered here is 1.77 ± 0.37 ^∘C EgC^−1 and is similar to that found in CMIP5 models (1.63 ± 0.48 ^∘C EgC^−1) but with somewhat reduced model spread. The expressions for feedback parameters based on the fully and biogeochemically coupled configurations of the 1pctCO2 simulation are simplified when the small temperature change in the biogeochemically coupled simulation is ignored. Decomposition of the terms of these simplified expressions for the feedback parameters is used to gain insight into the reasons for differing responses among ocean and land carbon cycle models.

中文翻译：

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CMIP6模型中的碳浓度和碳气候反馈及其与CMIP5模型的比较

从完全和生物地球化学耦合的模拟结果进行了分析，以分析 CO ₂ 从其工业化前值的¹ yr％^？1（1pctCO2）的增长率，以量化碳的强度。浓度和碳的气候反馈参数，分别测量海洋和陆地碳库对大气CO ₂浓度变化和全球气候变化的响应 。结果基于最新（第六个）耦合模型比较项目（CMIP6）的11个综合地球系统模型，并与第五个CMIP（CMIP5）的八个模型进行了比较。Carbon浓度反馈的强度在陆地上具有可比的大小（平均值±``标准偏差'' = ?? 0.97 ???? ± â???? 0.40A ???? PGCA ???? ppm的^{â???? 1}）和海洋（0.79埃???? ± â???? 0.07A ???? PGCA？ ??? ppm的^{â???? 1}），而在陆地上（在卡伯纳????气候反馈â???? 45.1 â???? ± â????50.6â???? PGCA？ ??? ^â???? ç ^{â???? 1}）比在海洋（约大3倍â???? 17.2 â???? ± â???? 5.0A ???? PGCA ???? ^â???? ç ^{â???? 1}）。两种反馈的强度都高一个数量级现有研究表明，陆地上的不确定性超过海洋上的不确定性。与CMIP5模型相比，这些值及其在11个CMIP6模型中的传播没有太大变化。对于包含氮循环表示形式的模型，土地的反馈参数绝对值较低。这里考虑的11种CMIP6模型对累积排放（TCRE）的瞬态气候响应为1.77 ???? ± â????0.37â???? ^{一种？？？？}CA ???? EGC ^{â???? 1}和处于CMIP5模型类似于实测值（1.63â???? ± â????0.48â???? ^â???? CA ??? ？EGC ^{â???? 1}），但模型传播有所减少。当忽略了生物地球化学耦合模拟中的小温度变化时，将简化基于1pctCO2模拟的完全和生物地球化学耦合配置的反馈参数的表达式。通过对这些简化表达式的反馈参数进行分解，可以深入了解海洋和陆地碳循环模型之间响应不同的原因。