Middle Miocene long-term continental temperature change in and out of pace with marine climate records

Katharina Methner,Andreas Mulch,Jens Fiebig,Marion Campani,Niklas Löffler,Oliver Kempf

doi:10.1038/s41598-020-64743-5

Abstract

Reconstructing long-term continental temperature change provides the required counterpart to age equivalent marine records and can reveal how terrestrial and marine temperatures were related during times of extreme climate change such as the Miocene Climatic Optimum (MCO) and the following Middle Miocene Climatic Transition (MMCT). Carbonate clumped isotope temperatures (T(Δ47)) from 17.5 to 14.0 Ma Central European paleosols (Molasse Basin, Switzerland) display a temperature pattern during the MCO that is similar to coeval marine temperature records. Maximum temperatures in the long-term soil T(Δ47) record (at 16.5 and 14.9 Ma) lag maximum ocean bottom water temperatures, lead global ice volume, and mark the initiation of minimum global ice volume phases. The suggested onset of the MMCT, deduced by a marked and rapid decline in Molasse Basin soil temperatures is coeval with cooling reported in high-latitudinal marine records. This is best explained by a change in the seasonal timing of soil carbonate formation that was likely driven by a modification of rainfall seasonality and thus by a major reorganization of mid-latitude atmospheric circulation across Central Europe. In particular, our data suggest a strong climate coupling between the North Atlantic and Central Europe already in the middle Miocene.

Highlights

Reconstructing long-term continental temperature change provides the required counterpart to age equivalent marine records and can reveal how terrestrial and marine temperatures were related during times of extreme climate change such as the Miocene Climatic Optimum (MCO) and the following Middle Miocene Climatic Transition (MMCT)
As the T(Δ47) values presented here are consistent with Central European paleobotanical-based warm month mean temperatures (WMMT) during the MCO and correspond to mean annual temperatures (MAT) during the MMCT14,17,19,20,50 as well as modelled MATs59–65 (Figs. 2A and 3C), we propose that MCO Δ47 temperatures from the Swiss North Alpine Foreland Basin (NAFB) reflect summer temperatures exclusively and that a change in rainfall seasonality and soil carbonate formation seasonality played an important role in determining T(Δ47) values during the MMCT
The NAFB paleosol T(Δ47) shows two warming peaks (>30 °C) that are bracketing the MCO with warm season temperatures typically >24 °C

Summary

Introduction

Reconstructing long-term continental temperature change provides the required counterpart to age equivalent marine records and can reveal how terrestrial and marine temperatures were related during times of extreme climate change such as the Miocene Climatic Optimum (MCO) and the following Middle Miocene Climatic Transition (MMCT). The suggested onset of the MMCT, deduced by a marked and rapid decline in Molasse Basin soil temperatures is coeval with cooling reported in high-latitudinal marine records. This is best explained by a change in the seasonal timing of soil carbonate formation that was likely driven by a modification of rainfall seasonality and by a major reorganization of mid-latitude atmospheric circulation across Central Europe. 17 to 15 Ma warm period of the Miocene Climatic Optimum (MCO) interrupted long-term Cenozoic cooling, declining pCO2 levels and Antarctic ice sheet build-up[1,2] and contrasts the subsequent middle Miocene Climate Transition (MMCT) that was marked by cooling of high and low latitudes, stabilization of Antarctic ice sheets, major sea level fall and marine biota overturn[3,4,5,6]. Napf alluvial fan 30 km Sample MC 946 MC 956B MC 965B MC 961B MC 975A MC 981B MC 1011B MC 1003A MC 1001 MC 991B MC 987B

Methods

Results

Discussion

Conclusion