Pliocene switch in orbital-scale carbon cycle/climate dynamics
Pliocene switch in orbital-scale carbon cycle/climate dynamics
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DOI：
10.1002/2014pa002651
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发表时间：
2014-12
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影响因子：
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通讯作者：
S. Turner
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文献类型：
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作者：
S. Turner
碳和氧同位素在底栖有孔虫的高频率（周期约105年）之间的关系，这两个代理最广泛地用于重建地球的碳循环和气候过去的变化，显示了两个不同的模式在新生代。第一种是“冰川式”模式，将δ 13 C的负偏移与δ 18 O的正偏移相关联，表明温度相对较低，冰量较大。第二种是“高温型”模式，它将δ 13 C的负偏移与δ 18 O的负偏移联系起来，表明变暖。在这里，我评估的连贯性和相位的这些高频率，轨道尺度的周期（特别是，~100 kyr偏心周期）在δ 13 C和δ 18 O从多个高分辨率底栖有孔虫记录跨越过去的地球历史的65万年，以确定这些模式是最持久的整个新生代，当这些模式之间的切换发生。我发现，冰川风格的δ 13 C-δ 18 O模式是一个功能，仅限于上新世-更新世，表明与北方冰川的开始，在碳循环和气候之间的相互作用的根本变化。尽管气候发生了显著的长期变化，但在新生代的大部分时间里，δ 13 C和δ 18 O之间高频关系的相对稳定性仍然存在，这可能表明陆地碳循环动力学对轨道强迫的二分法响应，在过去的500万年里发生了一次转换。
The high-frequency (periods of ~105 years) relationship between carbon and oxygen isotopes in benthic foraminifera—the two proxies most extensively used to reconstruct past changes in Earth's carbon cycle and climate—shows two distinct patterns across the Cenozoic. The first, “glacial-style,” pattern associates negative excursions in δ13C with positive excursions in δ18O indicative of relatively cold temperatures and greater ice volume. The second, “hyperthermal-style,” pattern associates negative excursions in δ13C with negative excursions in δ18O indicative of warming. Here I assess the coherence and phasing of these high-frequency, orbital-scale cycles (in particular, the ~100 kyr eccentricity period) in δ13C and δ18O from multiple high-resolution benthic foraminiferal records spanning the last ~65 million years of Earth history in order to identify which of these patterns is most persistent across the Cenozoic and when the switch between these patterns occurred. I find that the glacial-style δ13C-δ18O pattern is a feature restricted to the Plio-Pleistocene, suggesting a fundamental change in the interplay between the carbon cycle and climate associated with the onset of Northern Hemisphere glaciation. This relative stability of the high-frequency relationship between δ13C and δ18O across most of the Cenozoic persists despite significant secular changes in climate and may suggest a dichotomous response of terrestrial carbon cycle dynamics to orbital forcing with a switch occurring in the last ~5 Myr.