A symmetrical CO2 peak and asymmetrical climate change during the middle Miocene

Ji, Shunchuan; Nie, Junsheng; Lechler, Alex R.; Huntington, Katharine W.; Heitmann, Emma O.; Breecker, Daniel O.

doi:10.1016/j.epsl.2018.07.011

Cited by 49 publications

(45 citation statements)

References 54 publications

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“…2c) is independent of calibration error, based on universal gas-exchange mechanisms, and represents plant vegetative organs of multiple plant species that directly interacted with the available pool of atmospheric carbon dioxide. Previous Ca estimates from the Oligocene/Miocene boundary based on boron isotopes and paleosol carbonates are generally lower than our estimates (Ji et al, 2018;Greenop et al, 2019) (Fig. 4b), whereas Ca estimates based on stomatal index and recent alkenone-based Ca estimates are more similar to our results (Kürschner et al, 2008;Super et al, 2018).…”

Section: Earliest Miocene Co2supporting

confidence: 74%

“…Reconstructions of globally elevated temperatures of 5-6 °C in the early Miocene (Hansen et al, 2013) with a Ca of ~300 ppm (Ji et al, 2018;Greenop et al, 2019) upsets the expected ESS to Ca during this period (Henrot et al, 2010). Geochemical Ca proxy estimates consistently produce Ca estimates that are too low to satisfy ESS to Ca prior to the Pliocene (Royer, 2016) (Fig.…”

Section: Earliest Miocene Co2mentioning

confidence: 92%

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Elevated CO<sub>2</sub>, increased leaf-level productivity and water-use efficiency during the early Miocene

Reichgelt¹,

D'Andrea²,

Valdivia-McCarthy³

et al. 2020

Preprint

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Abstract. Rising atmospheric CO2 is expected to increase global temperatures, plant water-use efficiency, and carbon storage in the terrestrial biosphere. A CO2 fertilization effect on terrestrial vegetation is predicted to cause global greening as the potential ecospace for forests expands. However, leaf-level fertilization effects, such as increased productivity and water-use efficiency, have not been documented from fossil leaves in periods of heightened atmospheric CO2. Leaf gas-exchange rates reconstructed from early Miocene fossils which grew at southern temperate and tropical latitudes, when global average temperatures were 5–6 °C higher than today reveal that atmospheric CO2 was ~ 450–550 ppm. Early Miocene CO2 is similar to projected values for 2040AD, and consistent with Earth System Sensitivity of 3–7 °C to a doubling of CO2. While early Miocene leaves had photosynthetic rates similar to modern plants, southern temperate leaves were more productive than modern due to a longer growing season. This higher productivity was likely mirrored at northern temperate latitudes as well, where a greater availability of landmass would have led to increased carbon storage in forest biomass relative to today. Intrinsic water-use efficiency of both temperate and tropical forest trees was high, toward the upper limit of the range for modern trees, which likely expanded the habitable range in regions that could not support forests with high moisture demands under lower atmospheric CO2. Overall, early Miocene elevated atmospheric CO2 sustained globally higher temperatures and our results reveal the first empirical evidence of concomitant enhanced intrinsic water-use efficiency, indicating a forest fertilization effect.

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Section: Earliest Miocene Co2supporting

confidence: 74%

Section: Earliest Miocene Co2mentioning

confidence: 92%

Elevated CO<sub>2</sub>, increased leaf-level productivity and water-use efficiency during the early Miocene

Reichgelt¹,

D'Andrea²,

Valdivia-McCarthy³

et al. 2020

Preprint

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“…; Miao et al, 2011; Fig. 3E), whereas it is negatively correlated (r = -0.86) to the comprehensive pCO 2 record (Kürschner et al, 2008;Tripati et al, 2009;Foster et al, 2012;Greenop et al, 2014;Ji et al, 2018; Fig. 3F).…”

Section: Methods and Resultsmentioning

confidence: 86%

Miocene fire intensification linked to continuous aridification on the Tibetan Plateau

Miao

Warny

et al. 2019

Geology

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Although fire is considered an important factor in global vegetation evolution and climate change, few high-resolution Miocene fire records have been obtained worldwide. Here, two independent micro-charcoal-based fire records from the northern Tibetan Plateau were analyzed; both show similar trends in microcharcoal concentrations through time, with low abundances in the warmer Middle Miocene Climate Optimum (18-14 Ma) followed by a continuous increase throughout the late Miocene (14-5 Ma) cooling. Our detailed statistical analyses show that the micro-charcoal concentration trend is highly positively correlated to the trend in oxygen isotopes (δ 18 O, r = 0.94) and xerophytic species (% Xero , r = 0.95). We propose that the intensified fire frequency on the Tibetan Plateau mainly originated from the forest-steppe ecotone as a result of the continuous aridification in winter driven by the global cooling and decreased atmospheric pCO 2 that occurred during 18-5 Ma, with a secondary control by the tectonic activity of the northern Tibetan Plateau.

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“…CO 2 levels in this period exhibited some small volatility (Beerling & Royer, ; Ji et al, ), with an enigmatic decoupling between the climate, which was much warmer than todays (Pound et al, ; Zachos et al, ), and low atmospheric CO 2 concentrations (Pagani et al, ; Pearson & Palmer, ; Ruddiman, ). Recently, based on research using coccolithophorids and pennate diatoms, reconstructions have indicated a dramatic decrease in CO 2 concentrations during the Late Miocene, providing new evidence for the aforementioned enigma (Bolton et al, ; Bolton & Stoll, ; Mejía et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…However, the relative roles of concurrent regional tectonic activity and a decline in atmospheric CO 2 concentrations in driving the transitions evident in continental climate patterns and ecosystems remain debatable (Bradshaw et al, 2012;Herbert et al, 2016;Ruddiman, 2010). CO 2 levels in this period exhibited some small volatility (Beerling & Royer, 2011;Ji et al, 2018), with an enigmatic decoupling between the climate, which was much warmer than todays Zachos et al, 2001), and low atmospheric CO 2 concentrations (Pagani et al, 1999;Pearson & Palmer, 2000;Ruddiman, 2010). Recently, based on research using coccolithophorids and pennate diatoms, reconstructions have indicated a dramatic decrease in CO 2 concentrations during the Late Miocene, providing new evidence for the aforementioned enigma (Bolton et al, 2016;Bolton & Stoll, 2013;Mejía et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A Late Miocene Terrestrial Temperature History for the Northeastern Tibetan Plateau's Period of Tectonic Expansion

Chen

Bai

Fang

et al. 2019

Geophysical Research Letters

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Key Points The uplift event (~10.5–8 Ma) revealed by glycerol dialkyl glycerol tetraethers temperature records from the Xining Basin is synchronous with regional drying The cooling amplitude over land is less than that over the ocean during the CO2‐dominated Late Miocene cooling event (~7–5.4 Ma) Tectonic forcing, rather than pCO2, dominated regional continental climate patterns and ecosystem transitions during the Late Miocene

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A symmetrical CO2 peak and asymmetrical climate change during the middle Miocene

Cited by 49 publications

References 54 publications

Elevated CO<sub>2</sub>, increased leaf-level productivity and water-use efficiency during the early Miocene

Elevated CO<sub>2</sub>, increased leaf-level productivity and water-use efficiency during the early Miocene

Miocene fire intensification linked to continuous aridification on the Tibetan Plateau

A Late Miocene Terrestrial Temperature History for the Northeastern Tibetan Plateau's Period of Tectonic Expansion

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A symmetrical CO2 peak and asymmetrical climate change during the middle Miocene

Cited by 49 publications

References 54 publications

Elevated CO&lt;sub&gt;2&lt;/sub&gt;, increased leaf-level productivity and water-use efficiency during the early Miocene

Elevated CO&lt;sub&gt;2&lt;/sub&gt;, increased leaf-level productivity and water-use efficiency during the early Miocene

Miocene fire intensification linked to continuous aridification on the Tibetan Plateau

A Late Miocene Terrestrial Temperature History for the Northeastern Tibetan Plateau's Period of Tectonic Expansion

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Elevated CO<sub>2</sub>, increased leaf-level productivity and water-use efficiency during the early Miocene

Elevated CO<sub>2</sub>, increased leaf-level productivity and water-use efficiency during the early Miocene