New constraints on atmospheric CO2 concentration for the Phanerozoic
New constraints on atmospheric CO2 concentration for the Phanerozoic
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DOI：
10.1002/2014gl060457
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发表时间：
2014-07-16
影响因子：
5.2
通讯作者：
Berry, Joseph A.
中科院分区：
文献类型：
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作者：
Franks, Peter J.;Royer, Dana L.;Berry, Joseph A.
利用代用指标和地球化学碳循环模型估算了中生代地球大气CO2浓度c（a）。大多数估计都带有很大的，有时是无限的不确定性。在这里，我们计算严格约束的估计c（a）使用叶气体交换的通用方程，直接从化石叶的碳同位素组成和气孔解剖获得的关键变量。我们的新估计，验证对冰芯和直接测量的c（a），是小于1000 ppm的大多数中生代，从泥盆纪到现在，与森林的外观和全球扩散相一致。从蒙特卡罗模拟中获得的Underweight通常小于从其他方法获得的c（a）估计。这些结果为新出现的观点提供了关键的新的经验支持，即c（a）的大幅度（类似于2000-3000 ppm），长期波动并不表征后泥盆纪，地球对c（a）的长期气候敏感性比最初认为的要大。
Earth's atmospheric CO2 concentration (c(a)) for the Phanerozoic Eon is estimated from proxies and geochemical carbon cycle models. Most estimates come with large, sometimes unbounded uncertainty. Here, we calculate tightly constrained estimates of c(a) using a universal equation for leaf gas exchange, with key variables obtained directly from the carbon isotope composition and stomatal anatomy of fossil leaves. Our new estimates, validated against ice cores and direct measurements of c(a), are less than 1000 ppm for most of the Phanerozoic, from the Devonian to the present, coincident with the appearance and global proliferation of forests. Uncertainties, obtained from Monte Carlo simulations, are typically less than for c(a) estimates from other approaches. These results provide critical new empirical support for the emerging view that large (similar to 2000-3000 ppm), long-term swings in c(a) do not characterize the post-Devonian and that Earth's long-term climate sensitivity to c(a) is greater than originally thought.