TY - JOUR
T1 - A Holocene temperature (brGDGT) record from Garba Guracha, a high-altitude lake in Ethiopia
AU - Bittner, Lucas
AU - De Jonge, Cindy
AU - Gil-Romera, Graciela
AU - Lamb, Henry F.
AU - Russell, James M.
AU - Zech, Michael
N1 - Funding Information:
This research has been supported by the Deutsche Forschungsgemeinschaft (grant no. ZE 844/10–1).This open access publication was financed by the Saxon State and University Library Dresden (SLUB Dresden).
Funding Information:
This research was funded by the German Research Council (DFG, ZE 844/10–1) in the framework of the joint Ethio-European DFG Research Unit 2358 “The Mountain Exile Hypothesis: How humans benefited from and re-shaped African high altitude ecosystems during Quaternary climate changes”. We are grateful to the project coordination; the Philipps University of Marburg; Addis Ababa University; the Frankfurt Zoological Society; the Ethiopian Wolf Project; the Bale Mountains National Park; and the related staff members, especially Katinka Thielsen and Mekbib Fekadu, for their logistic assistance during our fieldwork. We thank the Ethiopian Wildlife Conservation Authority for permitting our research in the Bale Mountains National Park.
Publisher Copyright:
© Copyright:
PY - 2022/11/30
Y1 - 2022/11/30
N2 - Eastern Africa has experienced strong climatic changes since the last deglaciation (15g000 years ago). The driving mechanisms and teleconnections of these spatially complex climate variations are yet not fully understood. Although previous studies on lake systems have enhanced our knowledge of Holocene precipitation variation in eastern Africa, relatively few studies have reconstructed the terrestrial temperature history of eastern Africa from lake archives. Here, we present (i) a new branched glycerol dialkyl glycerol tetraether (brGDGT) temperature calibration that includes Bale Mountains surface sediments and (ii) a quantitative record of mean annual air temperature (MAT) over the past 12gkagcalgBP using brGDGTs in a sediment core collected from Garba Guracha (3950gmga.s.l.) in the Bale Mountains. After adding Bale Mountains surface sediment (nCombining double low line11) data (Baxter et al., 2019) to the existing East African lake dataset, additional variation in 6-methyl brGDGTs was observed, which necessitated modifying the MBT5ME′ calibration (MBT denotes methylation of branched tetraethers) by adding 6-methyl brGDGT IIIa′ (resulting in the MBT Bale Mountains index, r2Combining double low line0.93, p<0.05). Comparing the MBT5ME′ and the new MBT Bale Mountains index, our high-altitude Garba Guracha temperature record shows that warming occurred shortly after the Holocene onset when the temperature increased by more than 3.0gg-C in less than 600 years. The highest temperatures prevailed between 9 and 6gkacalBP, followed by a temperature decrease until 1.4gkacalBP. The reconstructed temperature history is linked to supraregional climatic changes associated with insolation forcing and the African Humid Period (AHP), as well as with local anomalies associated with catchment deglaciation and hydrology.
AB - Eastern Africa has experienced strong climatic changes since the last deglaciation (15g000 years ago). The driving mechanisms and teleconnections of these spatially complex climate variations are yet not fully understood. Although previous studies on lake systems have enhanced our knowledge of Holocene precipitation variation in eastern Africa, relatively few studies have reconstructed the terrestrial temperature history of eastern Africa from lake archives. Here, we present (i) a new branched glycerol dialkyl glycerol tetraether (brGDGT) temperature calibration that includes Bale Mountains surface sediments and (ii) a quantitative record of mean annual air temperature (MAT) over the past 12gkagcalgBP using brGDGTs in a sediment core collected from Garba Guracha (3950gmga.s.l.) in the Bale Mountains. After adding Bale Mountains surface sediment (nCombining double low line11) data (Baxter et al., 2019) to the existing East African lake dataset, additional variation in 6-methyl brGDGTs was observed, which necessitated modifying the MBT5ME′ calibration (MBT denotes methylation of branched tetraethers) by adding 6-methyl brGDGT IIIa′ (resulting in the MBT Bale Mountains index, r2Combining double low line0.93, p<0.05). Comparing the MBT5ME′ and the new MBT Bale Mountains index, our high-altitude Garba Guracha temperature record shows that warming occurred shortly after the Holocene onset when the temperature increased by more than 3.0gg-C in less than 600 years. The highest temperatures prevailed between 9 and 6gkacalBP, followed by a temperature decrease until 1.4gkacalBP. The reconstructed temperature history is linked to supraregional climatic changes associated with insolation forcing and the African Humid Period (AHP), as well as with local anomalies associated with catchment deglaciation and hydrology.
UR - http://www.scopus.com/inward/record.url?scp=85144445321&partnerID=8YFLogxK
U2 - 10.5194/bg-19-5357-2022
DO - 10.5194/bg-19-5357-2022
M3 - Article
AN - SCOPUS:85144445321
SN - 1726-4170
VL - 19
SP - 5357
EP - 5374
JO - Biogeosciences
JF - Biogeosciences
IS - 23
ER -
