Future climate forcing potentially without precedent in the last 420 million years.
Future climate forcing potentially without precedent in the last 420 million years.
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DOI：
10.1038/ncomms14845
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发表时间：
2017-04-04
影响因子：
16.6
通讯作者：
Lunt DJ
中科院分区：
文献类型：
--
作者：
Foster GL;Royer DL;Lunt DJ
地球气候在地质时间尺度上的演变在很大程度上是由太阳总辐照度（TSI）的变化和大气中温室气体含量的变化驱动的。在这里，我们表明，在过去的2.42亿年中，TSI缓慢增加了2.50 Wm−2（辐射强迫增加了2.99 Wm−2），这几乎完全被大气CO2的长期下降所抵消。这可能是由于硅酸盐风化的负反馈和陆地植物的扩张，共同确保了地球的长期可居住性。如果人类对化石燃料的使用不减，到二十一世纪中叶，二氧化碳排放量可能会达到始新世早期（5000万年前）以来的最高水平。如果二氧化碳继续上升到23世纪，那么与之相关的辐射强迫的大幅增加，以及地球系统将如何应对，在过去的5亿年中可能没有地质先例。尽管太阳输出增加，地球的气候显然在地质时期保持相对稳定。在这里，作者汇编了过去4.2亿年的大气二氧化碳数据，并表明这种气候反应是由于这种强大的温室气体的长期下降。
The evolution of Earth's climate on geological timescales is largely driven by variations in the magnitude of total solar irradiance (TSI) and changes in the greenhouse gas content of the atmosphere. Here we show that the slow ∼50 Wm−2 increase in TSI over the last ∼420 million years (an increase of ∼9 Wm−2 of radiative forcing) was almost completely negated by a long-term decline in atmospheric CO2. This was likely due to the silicate weathering-negative feedback and the expansion of land plants that together ensured Earth's long-term habitability. Humanity's fossil-fuel use, if unabated, risks taking us, by the middle of the twenty-first century, to values of CO2 not seen since the early Eocene (50 million years ago). If CO2 continues to rise further into the twenty-third century, then the associated large increase in radiative forcing, and how the Earth system would respond, would likely be without geological precedent in the last half a billion years. Despite an increase in solar output, the Earth's climate has apparently remained relatively stable over geological time. Here, the authors compile atmospheric CO2 data for the past 420 million years and show that this climatic response is due to the long-term decline in this powerful greenhouse gas.