Adam Hasenfratz

Adam Hasenfratz
Universität Bern | UniBe · Oeschger Centre for Climate Change Research

PhD

About

10
Publications
2,103
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332
Citations
Citations since 2017
7 Research Items
327 Citations
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
Introduction
Skills and Expertise

Publications

Publications (10)
Article
Full-text available
Past changes in ocean ¹⁴C disequilibria have been suggested to reflect the Southern Ocean control on global exogenic carbon cycling. Yet, the volumetric extent of the glacial carbon pool and the deglacial mechanisms contributing to release remineralized carbon, particularly from regions with enhanced mixing today, remain insufficiently constrained....
Article
The shoaling of the Central American Seaway (CAS) around 4.6 Ma (million years ago) is thought to have enhanced the Gulf Stream, strengthening the Atlantic Meridional Overturning Circulation and potentially influencing the evolution of Pliocene climate. Paleoclimate records indicate a buildup of heat and salt in the Caribbean and changes in the for...
Article
Resetting the glacial timer The periodicity of glacial cycles changed from 100,000 to 41,000 years during the middle of the Pleistocene epoch. Why? Hasenfratz et al. measured the oxygen isotope composition and magnesium/calcium ratio in benthic and planktonic foraminifera from the Antarctic in order to reconstruct changes in the rate of transfer of...
Article
Full-text available
Significance Conflicting sets of hypotheses highlight either the role of ice sheets or atmospheric carbon dioxide (CO 2 ) in causing the increase in duration and severity of ice age cycles ∼1 Mya during the Mid-Pleistocene Transition (MPT). We document early MPT CO 2 cycles that were smaller than during recent ice age cycles. Using model simulation...
Article
An important tool for deep-sea temperature reconstruction is Mg/Ca paleothermometry applied to benthic foraminifera. Foraminifera of the genus Melonis appear to be promising candidates for temperature reconstructions due to their wide geographical and bathymetric distribution, and their infaunal habitat, which was suggested to reduce secondary effe...
Article
The occurrence of manganese-rich coatings on foraminifera can have a significant effect on their bulk Mg/Ca ratios thereby biasing seawater temperature reconstructions. The removal of this Mn phase requires a reductive cleaning step, but this has been suggested to preferentially dissolve Mg-rich biogenic carbonate, potentially introducing an analyt...
Article
Full-text available
During the last interglacial period, global temperatures were ~2°C warmer than at present and sea level was 6 to 8 meters higher. Southern Ocean sediments reveal a spike in authigenic uranium 127,000 years ago, within the last interglacial, reflecting decreased oxygenation of deep water by Antarctic Bottom Water (AABW). Unlike ice age reductions in...

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