Publication Date:
2023-08-17
Description:
Earth's climate cooled markedly during the Late Miocene from 12 to 5 million years ago, with far-reaching consequences for global ecosystems. However, the driving forces of these changes remain controversial. A major obstacle to progress is the uncertainty over the role played by greenhouse gas radiative forcing. Here we present boron isotope compositions for planktonic foraminifera, which record carbon dioxide change for the interval of most rapid cooling, the Late Miocene Cooling event between 7 and 5 Ma. Our record suggests that CO₂ declined by some 100 ppm over this two-million year-long interval to a minimum at approximately 5.9 Ma. Having accounted non-CO₂ greenhouse gasses and slow climate feedbacks, we estimate global mean surface temperature change for a doubling of CO₂ - Equilibrium Climate Sensitivity - to be 3.9˚C (1.8–6.7 ˚C at 95% confidence) based on comparison of our record of radiative forcing from CO₂ with a record of global mean surface temperature change. We conclude that changes in CO₂ and climate were closely coupled during the latest Miocene and that Equilibrium Climate Sensitivity was within range of estimates for the late Pleistocene, other intervals of the Cenozoic, and the 21st century as presented by the Intergovernmental Panel on Climate Change.
Keywords:
154-926A; 154-926B; 154-926C; AGE; Boron, seawater, logarithmic base dissociation constant; Boron, total, seawater; boron isotopes; Calculated, see reference(s); Calculated according to Hain et al. (2018); Calculated according to Lear et al. (2015); Calculated from δ¹¹B, see reference; Calculated with seacarb package in R; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, uncertainty; Carbon dioxide, partial pressure; Carbonic acid, dissociation constant; Cibicides wuellerstorfi, δ13C; Cibicides wuellerstorfi, δ18O; Climate forcing from carbon dioxide; CO2; Comment; Date/Time of event; Depth, composite; DEPTH, sediment/rock; DRILL; Drilling/drill rig; Event label; Fractionation from Klochko et al. (2006); Globigerinoides ruber, Aluminium/Calcium ratio; Globigerinoides ruber, Boron/Calcium ratio; Globigerinoides ruber, Magnesium/Calcium ratio; Globigerinoides ruber, δ11B; Globigerinoides ruber, δ11B, uncertainty; Henry's law constant; Inductively coupled plasma - mass spectrometry (ICP-MS); Ion product of water; Joides Resolution; Late Miocene; Latitude of event; Leg154; Longitude of event; Multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS); pH; Reconstructed; Relative change in pH; Salinity; Salinity, uncertainty; Sample code/label; Sea surface temperature; Sea surface temperature, uncertainty; Smoothed ΔFCO₂; South Atlantic Ocean; Trilobatus sacculifer; δ11B, aqueous; δ11B, seawater, reconstructed; δ11B, seawater, reconstructed, uncertainty
Type:
Dataset
Format:
text/tab-separated-values, 3532 data points
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