Max-Planck-Institute for Meteorology, Bundesstrasse 53, 20146, Hamburg, Germany.
International Max-Planck Research School for Earth System Modeling, Bundesstrasse 53, 20146, Hamburg, Germany.
Nat Commun. 2019 Feb 21;10(1):885. doi: 10.1038/s41467-019-08633-z.
Most Earth system models agree that land will continue to store carbon due to the physiological effects of rising CO concentration and climatic changes favoring plant growth in temperature-limited regions. But they largely disagree on the amount of carbon uptake. The historical CO increase has resulted in enhanced photosynthetic carbon fixation (Gross Primary Production, GPP), as can be evidenced from atmospheric CO concentration and satellite leaf area index measurements. Here, we use leaf area sensitivity to ambient CO from the past 36 years of satellite measurements to obtain an Emergent Constraint (EC) estimate of GPP enhancement in the northern high latitudes at two-times the pre-industrial CO concentration (3.4 ± 0.2 Pg C yr). We derive three independent comparable estimates from CO measurements and atmospheric inversions. Our EC estimate is 60% larger than the conventionally used multi-model average (44% higher at the global scale). This suggests that most models largely underestimate photosynthetic carbon fixation and therefore likely overestimate future atmospheric CO abundance and ensuing climate change, though not proportionately.
大多数地球系统模型都认为，由于 CO 浓度升高的生理效应以及气候的变化有利于温度限制地区的植物生长，陆地将继续储存碳。但它们在碳吸收的数量上存在很大分歧。历史上 CO 的增加导致了增强的光合作用碳固定（总初级生产力，GPP），这可以从大气 CO 浓度和卫星叶面积指数测量中得到证明。在这里，我们利用过去 36 年卫星测量中对环境 CO 的叶面积敏感性，获得了在两倍于工业化前 CO 浓度（3.4±0.2PgCyr）的情况下，北方高纬度地区 GPP 增强的紧急约束（EC）估计值（3.4±0.2PgCyr）。我们从 CO 测量和大气反演中得出了三个独立的可比估计值。我们的 EC 估计值比传统上使用的多模型平均值高出 60%（在全球范围内高出 44%）。这表明，大多数模型在很大程度上低估了光合作用碳固定，因此可能高估了未来大气 CO 的丰度和随之而来的气候变化，尽管不是成比例的。
