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Zimmermann HH, Stoof-Leichsenring KR, Dinkel V, Harms L, Schulte L, Hütt MT, Nürnberg D, Tiedemann R, Herzschuh U. Marine ecosystem shifts with deglacial sea-ice loss inferred from ancient DNA shotgun sequencing. Nat Commun 2023; 14:1650. [PMID: 36964154 PMCID: PMC10039020 DOI: 10.1038/s41467-023-36845-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 02/20/2023] [Indexed: 03/26/2023] Open
Abstract
Sea ice is a key factor for the functioning and services provided by polar marine ecosystems. However, ecosystem responses to sea-ice loss are largely unknown because time-series data are lacking. Here, we use shotgun metagenomics of marine sedimentary ancient DNA off Kamchatka (Western Bering Sea) covering the last ~20,000 years. We traced shifts from a sea ice-adapted late-glacial ecosystem, characterized by diatoms, copepods, and codfish to an ice-free Holocene characterized by cyanobacteria, salmon, and herring. By providing information about marine ecosystem dynamics across a broad taxonomic spectrum, our data show that ancient DNA will be an important new tool in identifying long-term ecosystem responses to climate transitions for improvements of ocean and cryosphere risk assessments. We conclude that continuing sea-ice decline on the northern Bering Sea shelf might impact on carbon export and disrupt benthic food supply and could allow for a northward expansion of salmon and Pacific herring.
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Affiliation(s)
- Heike H Zimmermann
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, D-14473, Potsdam, Germany
- Department of Glaciology and Climate, Geological Survey of Denmark and Greenland (GEUS), DK-1350, Copenhagen, Denmark
| | - Kathleen R Stoof-Leichsenring
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, D-14473, Potsdam, Germany
| | - Viktor Dinkel
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, D-14473, Potsdam, Germany
- Constructor University Bremen, Computational Systems Biology, Bremen, D-28759, Germany
| | - Lars Harms
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Data Science Support, D-27568, Bremerhaven, Germany
| | - Luise Schulte
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, D-14473, Potsdam, Germany
| | - Marc-Thorsten Hütt
- Constructor University Bremen, Computational Systems Biology, Bremen, D-28759, Germany
| | - Dirk Nürnberg
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Ocean circulation and climate dynamics, D-24148, Kiel, Germany
| | - Ralf Tiedemann
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Marine Geology, D-27568, Bremerhaven, Germany
- MARUM, Center for Marine Environmental Sciences, University of Bremen, D-28334, Bremen, Germany
| | - Ulrike Herzschuh
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, D-14473, Potsdam, Germany.
- University of Potsdam, Institute of Biochemistry and Biology, D-14476, Potsdam, Germany.
- University of Potsdam, Institute of Environmental Sciences and Geography, D-14476, Potsdam, Germany.
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Ice and ocean constraints on early human migrations into North America along the Pacific coast. Proc Natl Acad Sci U S A 2023; 120:e2208738120. [PMID: 36745804 PMCID: PMC9963817 DOI: 10.1073/pnas.2208738120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Founding populations of the first Americans likely occupied parts of Beringia during the Last Glacial Maximum (LGM). The timing, pathways, and modes of their southward transit remain unknown, but blockage of the interior route by North American ice sheets between ~26 and 14 cal kyr BP (ka) favors a coastal route during this period. Using models and paleoceanographic data from the North Pacific, we identify climatically favorable intervals when humans could have plausibly traversed the Cordilleran coastal corridor during the terminal Pleistocene. Model simulations suggest that northward coastal currents strengthened during the LGM and at times of enhanced freshwater input, making southward transit by boat more difficult. Repeated Cordilleran glacial-calving events would have further challenged coastal transit on land and at sea. Following these events, ice-free coastal areas opened and seasonal sea ice was present along the Alaskan margin until at least 15 ka. Given evidence for humans south of the ice sheets by 16 ka and possibly earlier, we posit that early people may have taken advantage of winter sea ice that connected islands and coastal refugia. Marine ice-edge habitats offer a rich food supply and traversing coastal sea ice could have mitigated the difficulty of traveling southward in watercraft or on land over glaciers. We identify 24.5 to 22 ka and 16.4 to 14.8 ka as environmentally favorable time periods for coastal migration, when climate conditions provided both winter sea ice and ice-free summer conditions that facilitated year-round marine resource diversity and multiple modes of mobility along the North Pacific coast.
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Du J, Mix AC, Haley BA, Belanger CL, Sharon. Volcanic trigger of ocean deoxygenation during Cordilleran ice sheet retreat. Nature 2022; 611:74-80. [DOI: 10.1038/s41586-022-05267-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 08/23/2022] [Indexed: 11/06/2022]
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Late-Glacial and Holocene Lake-Level Fluctuations on the Kenai Lowland, Reconstructed from Satellite-Fen Peat Deposits and Ice-Shoved Ramparts, Kenai Peninsula, Alaska. QUATERNARY 2022. [DOI: 10.3390/quat5020023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recent decades of warmer climate have brought drying wetlands and falling lake levels to southern Alaska. These recent changes can be placed into a longer-term context of postglacial lake-level fluctuations that include low stands that were as much as 7 m lower than present at eight lakes on the Kenai Lowland. Closed-basin lakes on the Kenai Lowland are typically ringed with old shorelines, usually as wave-cut scarps, cut several meters above modern lake levels; the scarps formed during deglaciation at 25–19 ka in a kettle moraine topography on the western Kenai Lowland. These high-water stands were followed by millennia of low stands, when closed-basin lake levels were drawn down by 5–10 m or more. Peat cores from satellite fens near or adjoining the eight closed-basin lakes show that a regional lake level rise was underway by at least 13.4 ka. At Jigsaw Lake, a detailed study of 23 pairs of overlapping sediment cores, seismic profiling, macrofossil analysis, and 58 AMS radiocarbon dates reveal rapidly rising water levels at 9–8 ka that caused large slabs of peat to slough off and sink to the lake bottom. These slabs preserve an archive of vegetation that had accumulated on a lakeshore apron exposed during the preceding drawdown period. They also preserve evidence of a brief period of lake level rise at 4.7–4.5 ka. We examined plant succession using in situ peat sequences in nine satellite fens around Jigsaw Lake that indicated increased effective moisture between 4.6 and 2.5 ka synchronous with the lake level rise. Mid- to late-Holocene lake high stands in this area are recorded by numerous ice-shoved ramparts (ISRs) along the shores. ISRs at 15 lakes show that individual ramparts typically record several shove events, separated by hundreds or thousands of years. Most ISRs date to within the last 5200 years and it is likely that older ISRs were erased by rising lake levels during the mid- to late Holocene. This study illustrates how data on vegetation changes in hydrologically coupled satellite-fen peat records can be used to constrain the water level histories in larger adjacent lakes. We suggest that this method could be more widely utilized for paleo-lake level reconstruction.
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Globally resolved surface temperatures since the Last Glacial Maximum. Nature 2021; 599:239-244. [PMID: 34759364 DOI: 10.1038/s41586-021-03984-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 09/01/2021] [Indexed: 11/08/2022]
Abstract
Climate changes across the past 24,000 years provide key insights into Earth system responses to external forcing. Climate model simulations1,2 and proxy data3-8 have independently allowed for study of this crucial interval; however, they have at times yielded disparate conclusions. Here, we leverage both types of information using paleoclimate data assimilation9,10 to produce the first proxy-constrained, full-field reanalysis of surface temperature change spanning the Last Glacial Maximum to present at 200-year resolution. We demonstrate that temperature variability across the past 24 thousand years was linked to two primary climatic mechanisms: radiative forcing from ice sheets and greenhouse gases; and a superposition of changes in the ocean overturning circulation and seasonal insolation. In contrast with previous proxy-based reconstructions6,7 our results show that global mean temperature has slightly but steadily warmed, by ~0.5 °C, since the early Holocene (around 9 thousand years ago). When compared with recent temperature changes11, our reanalysis indicates that both the rate and magnitude of modern warming are unusual relative to the changes of the past 24 thousand years.
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Knudson KP, Ravelo AC, Aiello IW, Knudson CP, Drake MK, Sakamoto T. Causes and timing of recurring subarctic Pacific hypoxia. SCIENCE ADVANCES 2021; 7:eabg2906. [PMID: 34078607 PMCID: PMC11210308 DOI: 10.1126/sciadv.abg2906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
Several North Pacific studies of the last deglaciation show hypoxia throughout the ocean margins and attribute this phenomenon to the effects of abrupt warming and meltwater inputs. Yet, because of the lack of long records spanning multiple glacial cycles and deglaciation events, it is unclear whether deoxygenation was a regular occurrence of warming events and whether deglaciation and/or other conditions promoted hypoxia throughout time. Here, subarctic Pacific laminated sediments from the past 1.2 million years demonstrate that hypoxic events recurred throughout the Pleistocene as episodes of highly productive phytoplankton growth and were generally associated with interglacial climates, high sea levels, and enhanced nitrate utilization-but not with deglaciations. We suggest that hypoxia was typically stimulated by high productivity from iron fertilization facilitated by redox-remobilized iron from flooded continental shelves.
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Affiliation(s)
- Karla P Knudson
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Ana Christina Ravelo
- Department of Ocean Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| | - Ivano W Aiello
- Moss Landing Marine Laboratories, Moss Landing, CA 95039, USA
| | - Christina P Knudson
- Department of Mathematics, University of St. Thomas, 2115 Summit Avenue, St. Paul, MN 55105, USA
| | - Michelle K Drake
- Department of Ocean Sciences, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Tatsuhiko Sakamoto
- Graduate School and Faculty of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507, Japan
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Jaeger JM, Shevenell AE. Steering iceberg armadas. Science 2020; 370:662-663. [DOI: 10.1126/science.abe8461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Asian-Pacific tropics likely instigated millennial-scale climate changes
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Affiliation(s)
- John M. Jaeger
- Department of Geological Sciences, University of Florida, Gainesville FL 32611-2120, USA
| | - Amelia E. Shevenell
- College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA
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Walczak MH, Mix AC, Cowan EA, Fallon S, Fifield LK, Alder JR, Du J, Haley B, Hobern T, Padman J, Praetorius SK, Schmittner A, Stoner JS, Zellers SD. Phasing of millennial-scale climate variability in the Pacific and Atlantic Oceans. Science 2020; 370:716-720. [PMID: 33004677 DOI: 10.1126/science.aba7096] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 09/17/2020] [Indexed: 11/02/2022]
Abstract
New radiocarbon and sedimentological results from the Gulf of Alaska document recurrent millennial-scale episodes of reorganized Pacific Ocean ventilation synchronous with rapid Cordilleran Ice Sheet discharge, indicating close coupling of ice-ocean dynamics spanning the past 42,000 years. Ventilation of the intermediate-depth North Pacific tracks strength of the Asian monsoon, supporting a role for moisture and heat transport from low latitudes in North Pacific paleoclimate. Changes in carbon-14 age of intermediate waters are in phase with peaks in Cordilleran ice-rafted debris delivery, and both consistently precede ice discharge events from the Laurentide Ice Sheet, known as Heinrich events. This timing precludes an Atlantic trigger for Cordilleran Ice Sheet retreat and instead implicates the Pacific as an early part of a cascade of dynamic climate events with global impact.
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Affiliation(s)
- Maureen H Walczak
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA. .,Australian National University, Canberra ACT
| | - Alan C Mix
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Ellen A Cowan
- Department of Geological and Environmental Sciences, Appalachian State University, Boone, NC, USA
| | | | | | - Jay R Alder
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.,United States Geological Survey, Corvallis, OR, USA
| | - Jianghui Du
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.,Department of Earth Sciences, Institute of Geochemistry and Petrology, ETH Zurich, Zurich, Switzerland
| | - Brian Haley
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Tim Hobern
- Australian National University, Canberra ACT
| | - June Padman
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | | | - Andreas Schmittner
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
| | - Joseph S Stoner
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
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