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Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2018-39
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
04 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Rapid increase in simulated North Atlantic dust deposition due to fast change of northwest African landscape during the Holocene
Sabine Egerer1,2, Martin Claussen1,3, and Christian Reick1 1Max Planck Institute for Meteorology, Bundesstraße 53, 20146 Hamburg, Germany
2International Max Planck Research School on Earth System Modelling, Bundesstraße 53, 20146 Hamburg, Germany
3Center for Earth System Research and Sustainability, Universität Hamburg, Bundesstraße 53, 20146 Hamburg, Germany
Abstract. Marine sediment records from a series of core sites along the northwest African margin show a sudden increase in North Atlantic dust deposition about 5 ka BP that has been associated with an abrupt end of the African Humid Period (AHP). To assess the causes of the abrupt shift in North Atlantic dust deposition, we explore changes in the Holocene dust cycle and in North African climate and landscape by performing several time slice simulations from 8 ka BP until the pre-industrial era. Therefore, we use the coupled aerosol-climate model ECHAM6-HAM2 including dynamic vegetation and interactive dust, whereas ocean conditions and lake surface area are prescribed for each time slice.

We find a rapid increase in simulated dust deposition between 6 and 4 ka BP that is fairly consistent with the abrupt change in marine sediment records at around 20° N. The rapid change in simulated dust deposition is caused by a rapid increase in simulated dust emission in the western Sahara, where the main dust sources for dust transport towards the North Atlantic are located. The sudden increase in dust emission in the western Sahara is according to our simulations a consequence of a fast decline of vegetation cover from 22° N to 18° N that might occur due to vegetation-climate feedbacks or due to the existence of a precipitation threshold on vegetation growth. Additionally, the prescribed gradual reduction of lake area enforces accelerated dust release as highly productive dust sources are uncovered. Changes in the Saharan landscape and dust emission south of 18° N and in the eastern Sahara as well as changes in atmospheric circulation play a minor role in driving the dynamics of North Atlantic dust deposition at the core sites. Our study identifies spatial and temporal heterogeneity in the transition of the North African landscape. As a consequence, implications from local data records on large scale climate have to be treated with caution.

Citation: Egerer, S., Claussen, M., and Reick, C.: Rapid increase in simulated North Atlantic dust deposition due to fast change of northwest African landscape during the Holocene, Clim. Past Discuss., https://doi.org/10.5194/cp-2018-39, in review, 2018.
Sabine Egerer et al.
Sabine Egerer et al.
Sabine Egerer et al.

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We find a rapid increase in simulated dust deposition between 6 and 4 ka BP that is fairly consistent with an abrupt change in dust deposition that was observed in marine sediment records at around 5 ka BP. This rapid change is caused by a rapid increase in simulated dust emission in the western Sahara due to a fast decline of vegetation cover and a locally strong reduction of lake area. Our study identifies spatial and temporal heterogeneity in the transition of North African landscape.
We find a rapid increase in simulated dust deposition between 6 and 4 ka BP that is fairly...
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