The Mediterranean Sea turned repeatedly into an oxygen-deprived basin during the geological past, as evidenced by distinct sediment layers called sapropels. We use here records of the last sapropel S1 retrieved in front of the Nile River to explore the relationships between riverine input and seawater oxygenation. We decipher the seasonal cycle of fluvial input and seawater chemistry as well as the decisive influence of primary productivity on deoxygenation at millennial timescales.

Annually laminated lake sediments (varves) record past climate change at seasonal resolution. The VARved sediments DAtabase (VARDA) is created to utilize the full potential of varves for climate reconstructions. VARDA offers free access to a compilation and synchronization of standardized climate-proxy data, with applications ranging from reconstructing regional patterns of past climate change to validating simulations of climate models. VARDA is freely accessible at https://varve.gfz-potsdam.de

Due to chronology uncertainties within paleoclimate archives, it is unclear how climate oscillations from different records relate to one another. By using radionuclides to synchronize Greenland ice cores and a German lake record over 11 000 years, we show that two oscillations observed in these records were not synchronous but terminated and began with the onset of a grand solar minimum. Both this and changes in ocean circulation could have played a role in the two climate oscillations.

Our study presents the first seasonally laminated (varved) sediment record covering almost the entire Holocene in high mountainous arid Central Asia. The established floating varve chronology is confirmed by two terrestrial radiocarbon dates, whereby aquatic radiocarbon dates reveal decreasing reservoir ages up core. Changes in seasonal deposition characteristics are attributed to changes in runoff and precipitation and/or to evaporative summer conditions.

Abundances of plant biomarkers are compared with pollen data in a 3000-year climate archive covering the Late Glacial to Holocene transition in northern Poland. Both parameters synchronously show the rapid onset (12680–12600 yr BP) and termination (11580–11490 yr BP) of the Younger Dryas cold interval in the study area. This demonstrates the suitability of such proxies to record pronounced changes in vegetation cover without significant delay.

Our results provide a proof of concept for facilitating ¹⁰Be in varved lake sediments as a novel synchronization tool required for investigating leads and lags of proxy responses to climate variability. They also point to some limitations of ¹⁰Be in these archives mainly connected to in-lake sediment resuspension processes.

Multi-decadal to millennial flood frequency variations in the Mid- to Late Holocene in a flood layer record from Lake Ammersee is strongly related to the occurrence of extreme precipitation and temperatures in the northeastern Europe.

Here we present a unique 9.5 m palaeo-lacustrine record of 771 palaeofloods which occurred over a period of 10 000 years in the Piànico–Sèllere basin (southern Alps) during an interglacial period in the Pleistocene (sometime between 400 000 and 800 000 years ago). We analyse the palaeoflood series correlation, clustering, and cyclicity properties, finding a long-range cyclicity with a period of about 2030 years superimposed onto a fractional noise.

Currently, reconstructions of past changes in the hydrological cycle are usually qualitative, which is a major drawback for testing the accuracy of models in predicting future responses. Here we present a proof of concept of a novel approach to deriving quantitative paleohydrological data, i.e. changes in relative humidity, from lacustrine sediment archives, employing a combination of organic geochemical methods and plant physiological modeling.

Integrating discharge data of the River Ammer back to 1926 and a 5500-year flood layer record from an annually laminated sediment core of the downstream Ammersee allowed investigating changes in the frequency of major floods in Central Europe on interannual to multi-centennial timescales. Significant correlations between flood frequency variations in both archives and changes in the activity of the Sun suggest a solar influence on the frequency of these hydrometeorological extremes.

Micro-facies changes and elemental variations in deep Dead Sea sediments are used to reconstruct relative lake level changes for the early last glacial period. The results indicate a close link of hydroclimatic variability in the Levant to North Atlantic-Mediterranean climates during the time of the build-up of Northern Hemisphere ice shields. First petrographic analyses of gravels in the deep core question the recent hypothesis of a Dead Sea dry-down at the end of the last interglacial.