10 research outputs found
Sedimentological Studies of High Latitude Lake Sediments Aimed at Palaeoenvironmental Reconstructions: An Example from the Lena Delta Hinterland
Late Quaternary vegetation and lake system dynamics in northeastern Siberia: Implications for seasonal climate variability
Although the climate development over the Holocene in the Northern Hemisphere is well known,
palaeolimnological climate reconstructions reveal spatiotemporal variability in northern Eurasia. Here
we present a multi-proxy study from north-eastern Siberia combining sediment geochemistry, and
diatom and pollen data from lake-sediment cores covering the last 38,000 cal. years. Our results show
major changes in pyrite content and fragilarioid diatom species distributions, indicating prolonged
seasonal lake-ice cover between ~13,500 and ~8900 cal. years BP and possibly during the 8200 cal. years
BP cold event. A pollen-based climate reconstruction generated a mean July temperature of 17.8 �C
during the Holocene Thermal Maximum (HTM) between ~8900 and ~4500 cal. years BP. Naviculoid
diatoms appear in the late Holocene indicating a shortening of the seasonal ice cover that continues
today. Our results reveal a strong correlation between the applied terrestrial and aquatic indicators and
natural seasonal climate dynamics in the Holocene. Planktonic diatoms show a strong response to
changes in the lake ecosystem due to recent climate warming in the Anthropocene.
We assess other palaeolimnological studies to infer the spatiotemporal pattern of the HTM and affirm
that the timing of its onset, a difference of up to 3000 years from north to south, can be well explained by
climatic teleconnections. The westerlies brought cold air to this part of Siberia until the Laurentide icesheet
vanished 7000 years ago. The apparent delayed ending of the HTM in the central Siberian record
can be ascribed to the exceedance of ecological thresholds trailing behind increases in winter temperatures
and decreases in contrast in insolation between seasons during the mid to late Holocene as well as
lacking differentiation between summer and winter trends in paleolimnological reconstructions