We present an alternative radiocarbon (14C) age-depth model using IntCal20 to calibrate new accelerator mass spectrometry (AMS) data applied to a Lake Baikal sediment core (VER99G12) in southern Siberia. 14C dating showed that the core extends to 31 ka. To take into account uncertainties in 14C age and sedimentation depth in the core, a new age-depth modeling routine, undatable, was used in this study. Undatable revealed that significant changes in sedimentation rate correspond to global climate events, either warm or cold, which periods are likely close to the timing of the occurrence of the Meltwater pulses (MWP) at 19 and 14 ka, and the Last glacial Maximum (LGM) at 21–20 ka. Since the Selenga River accounts for 50% of the total river inflow to Lake Baikal, we interpret that these changes in sedimentation rate could be signals of significant changes in Selenga River discharge to the lake, which is expected to be affected by global climate change. Based on pollen analysis, it is highly probable that the sudden influx of the Selenga River to Lake Baikal, particularly at 19 ka, was due to the thawing of permafrost water through the Selenga River, which had developed in the region. Total organic carbon content and mean grain size increases concurrent with sedimentation rate, suggesting river inflow increased available nutrients for biological activity. Our results indicate that hydrological changes corresponding to MWP events can be observed in continental areas of the Northern Hemisphere.

This paper presents first chronological results for a Holocene marshland system from the southern part of the Danube-Tisza Interfluve. Radiocarbon (14C) ages were used to build age-depth models relying of probabilistic tools. Four models have been built: a linear one using dates gained via simple calibration, a P_Sequence model, fitting a polynomial function to calibrated dates; a Gamma_Sequence considering priori given and posterior accumulation rates have been constructed. As there was no significant difference between the mean values of individual models all seem suitable for establishing a reliable chronology despite differences in 95% CI ranges. While P_Sequence models underestimated SR, values calculated from the polynomial model were not significantly different from those of the G_Sequence. Based on multiproxy geochemical, sedimentological, paleoecological data the evolution of the system was reconstructed, covering a timespan of ca. 13,000 years starting from 12,000 BC and lasting until 1300 AD. Highest accumulation rates are dated to the Early Middle Ages from the 11th century. Several climate changes could have been identified which are present in other Hungarian and Western European records too, such as the 5b IRD event at ca. 5800 BC, a humid phase around 1600 BC, and a cool humid phase around the 6th century AD.

Paleoenvironments of the Torrey Pines State Reserve were reconstructed from a 3600-yr core from Los Peñasquitos Lagoon using fossil pollen, spores, charcoal, chemical stratigraphy, particle size, and magnetic susceptibility. Late Holocene sediments were radiocarbon dated, while the historical sediments were dated using sediment chemistry, fossil pollen, and historical records. At 3600 yr B.P., the estuary was a brackish-water lagoon. By 2800 yr B.P., Poaceae (grass) pollen increased to high levels, suggesting that the rising level of the core site led to its colonization by Spartina foliosa (cord-grass), the lowest-elevation plant type within regional estuaries. An increase in pollen and spores of moisture-dependent species suggests a climate with more available moisture after 2600 yr B.P. This change is similar to that found 280 km to the north at 3250 yr B.P., implying that regional climate changes were time-transgressive from north to south. Increased postsettlement sediment input resulted from nineteenth-century land disturbances caused by grazing and fire. Sedimentation rates increased further in the twentieth century due to closure of the estuarine mouth. The endemic Pinus torreyana (Torrey pine) was present at the site throughout this 3600-yr interval but was less numerous prior to 2100 yr B.P. This history may have contributed to the low genetic diversity of this species.