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The Paleocene-Eocene Thermal Maximum: A Geologic Analogue for Future Climate Change
9 February 2018
Thamer Alnasser, MSc Geoscience student reports on practical exercises in Palaeoceanography course.
Palaeoceanography offers valuable insights into past climates through extensive records documenting marine sedimentation processes for over than 100 million years before present time. The Integrated Ocean Drilling Program (IODP) has allowed access to this enormous archive, helping scientists to dive in deep through the geologic record and finding past geologic analogues that can provide invaluable evidence to the likely future climate response.
Approximately 56 million years ago, across the Paleocene-Eocene Thermal Maximum (PETM), A depletion in 13C approximately 4 – 5‰ was observed (Gehler et al., 2016). It has been simulated that carbon emissions required to cause such depletion range between 0.3 to 1.7 peta grams (1015) of carbon every year (Cui et al., 2011), which is much slower than modern day emission rates. During the PETM, global environmental shifts led to profound biologic consequences.
At UCL students get the opportunity to study the PETM, investigating a replica of an ocean floor sediment core retrieved from Walvis Ridge, ODP Leg 208, Site 1262 in the Southeastern Atlantic Ocean (photo). The aim of this practical exercise is to have a simulation of real-time work challenges, evaluating content from multiple modules and applying interdisciplinary knowledge to interpret observations scientifically.
An abrupt change in colour from pale brown carbonate to red clay is observed, the underlying carbonates were dominantly composed of calcareous nannofossils, these nannofossils completely disappear with the deposition of the red clay. Students get to utilise their newly acquired knowledge to understand the mechanisms leading to such abrupt change at the PETM and build up on concepts from other modules to explain the recovery process.
Further Reading:
- Cui et al., (2011). Slow Release of Fossil Carbon During the Palaeocene–Eocene Thermal Maximum. Nature Geoscience 4: 481–485.
- Gehler et al., (2016). Temperature and Atmospheric CO2 Concentration Estimates Through the PETM Using Triple Oxygen Isotope Analysis of Mammalian Bioapatite. Proc. Natl. Acad. Sci. USA. 113(28): 7739–7744.