Holocene Hydroclimatic Reorganizations in Northwest Canada Inferred From Lacustrine Carbonate Oxygen Isotopes
Sub‐centennial oxygen (δ18O) isotopes of ostracod and authigenic calcite from Squanga Lake provides evidence of hydroclimatic extremes and a series of post‐glacial climate system reorganizations for the interior region of northwest Canada. Authigenic calcite δ18O values range from −16‰ to −21‰ and a...
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Veröffentlicht in: | Geophysical research letters 2021-08, Vol.48 (16), p.n/a |
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Sprache: | eng |
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Zusammenfassung: | Sub‐centennial oxygen (δ18O) isotopes of ostracod and authigenic calcite from Squanga Lake provides evidence of hydroclimatic extremes and a series of post‐glacial climate system reorganizations for the interior region of northwest Canada. Authigenic calcite δ18O values range from −16‰ to −21‰ and are presently similar to modern lake water and annual precipitation values. Ostracod δ18O record near identical trends with calcite, offset by +1.7 ± 0.6‰. At 11 ka BP (kaBP = thousands of years before 1950), higher δ18O values reflect decreased precipitation−evaporation (P−E) balance from residual ice sheet influences on moisture availability. A trend to lower δ18O values until ∼8 ka BP reflects a shift to wetter conditions, and reorganization of atmospheric circulation. The last millennium and modern era are relatively dry, though not as dry as the early Holocene extreme. North Pacific climate dynamics remained an important driver of P−E balance in northwest Canada throughout the Holocene.
Plain Language Summary
To place recent environmental change around the Arctic in context, it is necessary to document change during time periods warmer than present, such as the early Holocene. A particularly useful tool to document changes in hydrology and climate over time, such as the balance between precipitation minus evaporation (P−E) are oxygen isotopes from lake sediment cores containing calcite. While previous studies documented changes in drought and changing atmospheric circulation patterns since ∼8,000 years ago, continuous records across the deglacial period are lacking. By extending to 11,000 years ago, this study adds to our understanding of previous hydroclimates, when rapid warming followed deglaciation. Results document a broader range of climatic extremes and variability than during historical periods driven by long‐term insolation and vapor source changes. While the Yukon was cooler and wetter between ∼8,000 and 1,000 years ago, recent warming and drying trends that began during the past millennia are comparable to hydroclimate between ∼11,000 and 8,000 years ago.
Key Points
An ∼11,000‐years oxygen isotope record from Squanga Lake documents boreal interior hydroclimatic change in the Yukon Territory
A dry climate characterized the early and late Holocene while wetter conditions persisted during the middle Holocene
The Holocene record frames modern conditions and serves to decipher the processes influencing regional hydroclimate |
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ISSN: | 0094-8276 1944-8007 |
DOI: | 10.1029/2021GL092948 |