EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Intense mid-Holocene warming on highland Sumatra: insights from biomarker proxies

Petter Hällberg1, Antonio Martínez Cortizas2, Anggi Hapsari3, Hamidi Rifai4, Steffen Eisele5, Caroline Bouvet de Maisonneuve5, Malin Kylander1, Frederik Schenk1, and Rienk Smittenberg1
Petter Hällberg et al.
  • 1Stockholm University, Sweden
  • 2Universidade de Santiago de Compostela
  • 3University of Goettingen, Germany
  • 4Universitas Negeri Padang, Indonesia
  • 5Nanyang Technological University, Singapore

Despite immense progress in the last decades, the Holocene climate evolution is still poorly resolved, in particular in the tropics, and especially from a terrestrial perspective. Here we reconstruct 11 000 years of paleo-climate and environment in the western Indo-Pacific Warm Pool – “the heat and steam engine of the world” – by analysing biomarker and geochemical proxies in peat sediments from Sumatra.

We discuss the composition of archaeal and bacterial membrane lipids (branched and isoprenoid glycerol dialkyl glycerol tetraethers; GDGTs) and their relationship with temperature and other environmental conditions. By analysing the hydrogen isotopes of leaf waxes (dDwax) we reconstruct past rainfall amounts.

X-Ray Fluorescence (XRF) derived geochemical composition reveals changes in erosional regimes. Additionally, we use long-chain n-alkane distributions, carbon and nitrogen analysis, and attenuated reflectance Fourier-Transform Infrared analysis (FTIR-ATR) to investigate changes in vegetation on the peatland.

Three main climate-environmental phases emerge in our record: 1) Relatively cold, dry and unstable conditions during the Early Holocene which is marked by high detrital input into the peatland. 2) Warm, wet and stable conditions coincided with the mid-Holocene period, 8.2 – 3.2 ka BP. Using a global peat-specific temperature calibration based on branched GDGTs (Naafs et al., 2017), we derive mean annual air temperatures peaking at 4.8 ka BP that are ~3 °C warmer compared to core-top and modern local weather station data. The warmest period is also the wettest according to dDwax, which is further supported by GDGT and alkane distributions, and d13C values indicating aquatic biomass production. 3) At 3.2 ka BP, the climate abruptly deteriorated into colder and drier conditions and re-intensified erosion.

Surprisingly, slope wash events resulting in input of coarse detrital material into the core were most frequent during the dry periods. We suggest that this is related to a more variable hydroclimate with droughts and episodic heavy rains, likely associated with ENSO variability, causing increased erosion during the Early and Late Holocene.


How to cite: Hällberg, P., Martínez Cortizas, A., Hapsari, A., Rifai, H., Eisele, S., Bouvet de Maisonneuve, C., Kylander, M., Schenk, F., and Smittenberg, R.: Intense mid-Holocene warming on highland Sumatra: insights from biomarker proxies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13242,, 2022.


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