Alkenone and boron based Oligocene pCO2 records

• Main Authors: Seki, Osamu, Foster, Gavin L, Schmidt, Daniela N, Mackensen, Andreas, Kawamura, Kimitaka, Pancost, Richard D
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2010
• Subjects: 154-925E; 154-926A; 154-927B; 154-928A; 154-929A; 165-999A; 202-1241A; Caribbean Sea; DRILL; Drilling/drill rig; Joides Resolution; Leg154; Leg165; Leg202; North Atlantic Ocean; North Pacific Ocean; Ocean Drilling Program; ODP; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.732923; https://doi.org/10.1594/PANGAEA.732923

The Pliocene period is the most recent time when the Earth was globally significantly (~3°C) warmer than today. However, the existing pCO2 data for the Pliocene are sparse and there is little agreement between the various techniques used to reconstruct palaeo-pCO2. Moreover, the temporal resolution of the published records does not allow a robust assessment of the role of declining pCO2 in the intensification of the Northern Hemisphere Glaciation (INHG) and a direct comparison to other proxy records are lacking. For the first time, we use a combination of foraminiferal (delta11B) and organic biomarker (alkenone-derived carbon isotopes) proxies to determine the concentration of atmospheric CO2 over the past 5 Ma. Both proxy records show that during the warm Pliocene pCO2 was between 330 and 400 ppm, i.e. similar to today. The decrease to values similar to pre-industrial times (275-285 ppm) occurred between 3.2 Ma and 2.8 Ma - coincident with the INHG and affirming the link between global climate, the cryosphere and pCO2.