EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Orbital CO2 cycles and the Mid-Pleistocene Transition

Thomas Chalk1, Mathis Hain2, Gavin Foster1, Sophie Nuber3,4, Eelco Rohling1,5, Stephen Barker3, Soraya Cherry1, and Paul Wilson1
Thomas Chalk et al.
  • 1Ocean and Earth Science, University of Southampton, Southampton, SO14 3ZH, United Kingdom.
  • 2Earth & Planetary Sciences Department, 1156 High Street, Earth and Planetary Sciences Santa Cruz CA 95064, United States of America
  • 3School of Earth and Ocean Sciences, 2.28, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
  • 4School of Geography & Geosciences, Irvine Building, University of St Andrews, North Street, St Andrews, KY16 9AL, UK
  • 5Research School of Earth Sciences, The Australian National University, Canberra 2601, Australia.

Over the past 1.5 million years, Earth’s climate has shifted from a predominantly 41 thousand year (kyr) dominated climate cycle to one dominated by longer and larger glacial-interglacial cycles, known as the Mid-Pleistocene Transition (MPT). The MPT occurs over a period of several hundreds of thousands of years, with little change to Earth’s external orbital forcing, thus implicating internal climate feedbacks. Here we interrogate the current capacity, and future potential, of boron isotope records to provide high quality carbon cycle information for the Pleistocene. We also present a compilation of boron isotope-derived pH-CO2 records from low-latitude ocean drill cores which closely follow the evolution of atmospheric CO2 over the ice core interval but extend it to 1.5 million years ago with a resolution of up to ~1 sample per 3 kyr. This new, near continuous δ11B-derived CO2 record is compared against other independent CO2 data from blue-ice cores and records of ocean and climate change., This confirms there is a decline in mean CO2 across the MPT which manifests as a lengthening and deepening of glacial CO2, and highlights the distinct difference in the nature of CO2 cycles in the 41-kyr world.


How to cite: Chalk, T., Hain, M., Foster, G., Nuber, S., Rohling, E., Barker, S., Cherry, S., and Wilson, P.: Orbital CO2 cycles and the Mid-Pleistocene Transition, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11682,, 2020