An Early Pleistocene atmospheric CO2 record based on pedogenic carbonate from the Chinese loess deposits

Da, Jiawei; Zhang, Yige; Wang, Hongtao; Balsam, William; Ji, Junfeng

doi:10.1016/j.epsl.2015.05.053

Cited by 18 publications

(13 citation statements)

References 45 publications

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“…If, on the other hand, the Pliocene T. sacculifer-based pCO 2 estimates are correct, Pliocene pCO 2 was less elevated relative to early Pleistocene pCO 2 values and the linear relationship between benthic δ 18 O and pCO 2 forcing extended into the Pliocene (Figure 9a). The T. sacculifer-based estimates, with pCO 2 likely <350-400 μatm, support the evidence for lower Pliocene pCO 2 from other proxies (Figure 8): alkenone δ 13 C, stomatal indices, and paleosols (e.g., Badger et al, 2013;Da et al, 2015;Wang et al, 2015) and implies that atmospheric pCO 2 was relatively similar between the late Pliocene and early Pleistocene, despite the descent into cooler polar temperatures. If correct, this record implies that Arctic temperatures declined at the Plio-Pleistocene transition due to factors other than direct radiative pCO 2 forcing, such as the thickening of northern hemisphere ice sheets or reduced poleward oceanic heat transport.…”

Section: Paleoceanography and Paleoclimatologysupporting

confidence: 70%

“…The text discusses potential offsets due to evolutionary changes in foraminiferal physiology and consequent species-differences between pH and pCO 2 reconstructions. Paleo-pCO 2 reconstructions from paleosols (Da et al, 2015), stomatal indices (Kürschner et al, 1996;Retallack, 2009;Stults et al, 2011;Wang et al, 2015), and alkenone δ 13 C (Badger et al, 2013;Seki et al, 2010;Zhang et al, 2013)…”

Section: Figurementioning

confidence: 99%

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Early Pleistocene Obliquity‐Scale pCO₂ Variability at ~1.5 Million Years Ago

Dyez

Hönisch

Schmidt

2018

Paleoceanog and Paleoclimatol

103

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In the early Pleistocene, global temperature cycles predominantly varied with ~41‐kyr (obliquity‐scale) periodicity. Atmospheric greenhouse gas concentrations likely played a role in these climate cycles; marine sediments provide an indirect geochemical means to estimate early Pleistocene CO2. Here we present a boron isotope‐based record of continuous high‐resolution surface ocean pH and inferred atmospheric CO2 changes. Our results show that, within a window of time in the early Pleistocene (1.38–1.54 Ma), pCO2 varied with obliquity, confirming that, analogous to late Pleistocene conditions, the carbon cycle and climate covaried at ~1.5 Ma. Pairing the reconstructed early Pleistocene pCO2 amplitude (92 ± 13 μatm) with a comparably smaller global surface temperature glacial/interglacial amplitude (3.0 ± 0.5 K) yields a surface temperature change to CO2 radiative forcing ratio of S[CO2]~0.75 (±0.5) °C−1·W−1·m−2, as compared to the late Pleistocene S[CO2] value of ~1.75 (±0.6) °C−1·W−1·m−2. This direct comparison of pCO2 and temperature implicitly incorporates the large ice sheet forcing as an internal feedback and is not directly applicable to future warming. We evaluate this result with a simple climate model and show that the presumably thinner, though extensive, northern hemisphere ice sheets would increase surface temperature sensitivity to radiative forcing. Thus, the mechanism to dampen actual temperature variability in the early Pleistocene more likely lies with Southern Ocean circulation dynamics or antiphase hemispheric forcing. We also compile this new carbon dioxide record with published Plio‐Pleistocene δ11B records using consistent boundary conditions and explore potential reasons for the discrepancy between Pliocene pCO2 based on different planktic foraminifera.

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Section: Paleoceanography and Paleoclimatologysupporting

confidence: 70%

Section: Figurementioning

confidence: 99%

Early Pleistocene Obliquity‐Scale pCO₂ Variability at ~1.5 Million Years Ago

Dyez

Hönisch

Schmidt

2018

Paleoceanog and Paleoclimatol

103

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“…Not only are dolomite and calcite totally dissolved in these paleosols and no secondary carbonates present, but also, the dolomite in the top portions of the underlying loess is lost to leaching. The carbonates usually reprecipitate to form thick calcium nodule layers in the loess [ Liu , ; Wang and Zheng , ] below the zone where dolomite is leached; for example, nodules of S1 were found in the underlying L2 unit at LT and BJ sections [ Da et al ., ]. This dissolution phase is seen in S1 paleosols in the southeastern LC, LT, and BJ sections, which show a leaching loss of dolomite in the top of the L2 layer (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Dolomite abundance in Chinese loess deposits: A new proxy of monsoon precipitation intensity

Meng

Liu

Balsam

et al. 2015

Geophysical Research Letters

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Dolomite of detrital origin in carbonate‐rich soil can help indicate the intensity of carbonate dissolution and leaching processes. Using Fourier transform infrared spectroscopy, we generated a high‐resolution record of dolomite and calcite contents from eight sections on the Chinese Loess Plateau spanning the last 130 kyr. Based on the relative abundance of calcite and dolomite, four dissolution phases of carbonate minerals related to summer monsoon (SM) variations are identified as follows: (1) coexistence of dolomite and calcite indicating a very weak SM with a mean annual precipitation (MAP) < 610 mm; (2) calcite without dolomite indicating a weak SM, 610 < MAP < 690 mm; (3) both dolomite and calcite are absent, but there is no downward leaching indicating a strong SM, 690 < MAP < 725 mm; and (4) both dolomite and calcite are absent, and downward leaching of the underlying loess layer suggesting a very strong SM with MAP > 725 mm.

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“…(c) 87 Sr/ 86 Sr ratios in marine sediments from the Indian Ocean 57 ; these values are much lower than those in materials from the Tibetan Plateau 58 , but they begin to increase after the Pliocene–Pleistocene boundary. (d) Atmospheric CO 2 levels estimated from marine sediments, shown in purple 60 ; CO 2 levels estimated from terrestrial soil carbonate indices, shown in orange 61 . Atmospheric CO 2 levels show a large decrease after 2.6 Ma. …”

Section: Discussionmentioning

confidence: 99%

A seven-million-year hornblende mineral record from the central Chinese Loess Plateau

Liu

Chen

et al. 2017

Sci Rep

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Previous studies of the late Cenozoic erosion rate have yielded different views—long-term stable rates or a significant increase at climate transitions—leading to uncertainty concerning the hypothesized global erosion rate controlled by either tectonic uplift or climatic changes. Here, we present a seven-million-year hornblende mineral record along the Lingtai section of the Chinese Loess Plateau. By examining the spatial distribution of hornblende minerals in seven desert basins, which are potential loess source areas, we constructed a ratio of hornblende versus total heavy minerals to reflect past changes in physical/chemical weathering strength. Our results demonstrate that the ratio has generally increased since 7 Ma, with three significant shifts recorded at 2.6 Ma, 1.4 Ma and 0.5 Ma linked to the onset, continuation and expansion of the Northern Hemisphere glaciation, respectively. Given that chemical weathering during the diagenetic history produces a trend of smoothly increasing hornblende migrating upwards, the three shifts at these boundaries can be interpreted as changes in the bedrock erosion rate on the northern Tibetan Plateau, which may be related to tectonic uplift events and incision of the Yellow River. Evidence presented here supports the idea of coupling between climate change, tectonic uplift and regional erosion.

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An Early Pleistocene atmospheric CO2 record based on pedogenic carbonate from the Chinese loess deposits

Cited by 18 publications

References 45 publications

Early Pleistocene Obliquity‐Scale pCO₂ Variability at ~1.5 Million Years Ago

Early Pleistocene Obliquity‐Scale pCO₂ Variability at ~1.5 Million Years Ago

Dolomite abundance in Chinese loess deposits: A new proxy of monsoon precipitation intensity

A seven-million-year hornblende mineral record from the central Chinese Loess Plateau

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An Early Pleistocene atmospheric CO2 record based on pedogenic carbonate from the Chinese loess deposits

Cited by 18 publications

References 45 publications

Early Pleistocene Obliquity‐Scale pCO2 Variability at ~1.5 Million Years Ago

Early Pleistocene Obliquity‐Scale pCO2 Variability at ~1.5 Million Years Ago

Dolomite abundance in Chinese loess deposits: A new proxy of monsoon precipitation intensity

A seven-million-year hornblende mineral record from the central Chinese Loess Plateau

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Early Pleistocene Obliquity‐Scale pCO₂ Variability at ~1.5 Million Years Ago

Early Pleistocene Obliquity‐Scale pCO₂ Variability at ~1.5 Million Years Ago