Hydroclimate extreme events detected by a sub-decadal diatom oxygen isotope record of the last 220 years from Lake Khamra, Siberia

• Main Authors: Stieg, Amelie, Biskaborn, Boris K., Herzschuh, Ulrike, Strauss, Jens, Pestryakova, Luidmila, Meyer, Hanno
• Format: Text
• Language: English
• Published: 2023
• Subjects: Arctic; Climate change; Sea ice; Siberia
• Online Access: https://doi.org/10.5194/cp-2023-85; https://cp.copernicus.org/preprints/cp-2023-85/

Northern latitudes have been significantly impacted by recent climate warming, which has increased the probability of experiencing extreme weather events. To comprehensively understand hydroclimate change and reconstruct extreme events such as droughts or floods, appropriate proxy records reaching further back in time are needed beyond meteorological measurements. Here we present a 220-year (2015–1790 CE), gapless stable oxygen isotope record of diatoms (δ 18 O diatom ) from Lake Khamra (59.99° N, 112.98° E) in Eastern Siberia, an area highly sensitive to climate change and with a demand for palaeohydrological data. From a 210 Pb- 137 Cs-dated sediment short core, this high-resolution proxy record was analysed to reconstruct hydroclimatic extremes on a sub-decadal scale. The interpretation of the δ 18 O diatom is supported by meteorological data, modern isotope hydrology, the ratio of planktonic-to-benthic diatom species and geochemical analyses of the same sediment indicative for the conditions in lake and catchment. A comparison with meteorological data back to 1930 revealed that the δ 18 O diatom record of Lake Khamra is primarily influenced by regional precipitation changes rather than air temperature. We identified winter precipitation, which enters the lake as isotopically-depleted snowmelt water, as the key process impacting the diatom isotope variability. We related the overall depletion of δ 18 O diatom in recent decades to an observed increase in winter precipitation in the area, likely associated with the global air temperature rise, Arctic sea ice retreat and increased moisture transport inland. Available palaeoclimate proxy records, including a fire reconstruction of the same lake, support the new record as a valuable hydroclimate proxy indicative for precipitation deficits, tendentially excluding solar insolation and air temperature as driving forces even beyond meteorological recordings. We identified two hydroclimatic extremes in the Lake Khamra δ 18 O diatom record, one at the beginning of the ...