Rapid Atlantification along the Fram Strait at the beginning of the 20th century

Science Advances, Journal Year: 2021, Volume and Issue: 7(48)

Published: Nov. 24, 2021

The recent expansion of Atlantic waters into the Arctic Ocean represents undisputable evidence rapid changes occurring in this region. Understanding past variability “Atlantification” is thus crucial providing a longer perspective on modern changes. Here, we reconstruct history Atlantification along eastern Fram Strait during 800 years using precisely dated paleoceanographic records based organic biomarkers and benthic foraminiferal data. Our results show water mass properties that commenced early 20th century—several decades before documented by instrumental records. Comparison with regional suggests poleward subtropical since end Little Ice Age response to hydrographic reorganization North Atlantic. mechanism will require further investigations climate model simulations.

Language: Английский

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Greening of Svalbard in the twentieth century driven by sea ice loss and glaciers retreat

Communications Earth & Environment, Journal Year: 2025, Volume and Issue: 6(1)

Published: Jan. 16, 2025

The greening of previously barren landscapes in the Arctic is one most relevant responses terrestrial ecosystem to climate change. Analyses satellite data (available since ~1980) have revealed a widespread tundra advance consistent with recent global warming, but length insufficient resolve long-term variability and precise timing onset. Here, we measured plant-derived biomarkers from an fjord sediment core as proxies for reconstructing past changes vegetation during transition Little Ice Age modern warming. Our findings rapid expansion beginning twentieth century, largely coinciding decline summer sea ice extent glacier retreat. trend inferred biomarker analysis peaked significantly late 1990s, along shift community towards more mature successional stage. Most these signals were biomolecular fingerprints vascular plant species that are adapted warmer conditions widely expanded proglacial areas decades. results suggest fjords may occurred earlier than thought, improving our mechanistic understanding vegetation-climate-cryosphere interactions will shape under future warming projections. tundra's century has been driven by retreat, according Svalbard.

Language: Английский

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Fossil organic carbon utilization in marine Arctic fjord sediments by subsurface micro-organisms

Nature Geoscience, Journal Year: 2023, Volume and Issue: 16(7), P. 625 - 630

Published: June 1, 2023

Abstract Rock-derived or petrogenic organic carbon has traditionally been regarded as being non-bioavailable and bypassing the active cycle when eroded. However, it become apparent that this might not be so inert, especially in fjord systems where influxes can high, making its degradation another potential source of greenhouse gas emissions. The extent to which subsurface micro-organisms use is well constrained, despite impacts on global cycling. Here, we performed compound-specific radiocarbon analyses intact polar lipid–fatty acids live from marine sediments Hornsund Fjord, Svalbard. By means, estimate local bacterial communities utilize between 5 ± 2% 55 6% (average 25 16%) for their biosynthesis, providing evidence important role a substrate after sediment redeposition. We hypothesize lack sufficient recently synthesized primary production forces into utilization an alternative energy source. input subsequent by represents natural fossil emissions over geological timescales.

Language: Английский

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Disentangling Effects of Sea Surface Temperature and Water Depth on Hydroxylated Isoprenoid GDGTs: Insights From the Hadal Zone and Global Sediments

Geophysical Research Letters, Journal Year: 2023, Volume and Issue: 50(15)

Published: Aug. 8, 2023

Abstract Hydroxylated isoprenoid glycerol dialkyl tetraethers (OH‐GDGTs) preserved in marine sediments are thought to be controlled by sea surface temperature (SST). However, water depth may also exert a significant influence on OH‐GDGTs. Here, we investigated sedimentary OH‐GDGTs the Kermadec and Atacama trench regions (2,560–9,560 m depth). Sedimentary hadal trenches were dominated OH‐GDGT‐0 (72 ± 8%), potentially reflecting an adaption of source organisms ambient cold deep water. This result, combined with global data set, revealed that predominance is ubiquitous phenomenon deep‐sea sediments, leading considerable underestimation RI‐OH′‐derived SSTs. By considering both SST effects, developed more accurate OH‐GDGT‐based paleothermometers for shallow ocean, encompassing full‐ocean‐depth range. Our findings highlight importance accounting effect provide improved tools reconstructing paleo‐SSTs.

Language: Английский

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Evaluating isoprenoidal hydroxylated GDGT-based temperature proxies in surface sediments from the global ocean

Geochimica et Cosmochimica Acta, Journal Year: 2023, Volume and Issue: 370, P. 113 - 127

Published: Dec. 19, 2023

Recently developed temperature proxies based on hydroxylated isoprenoid Glycerol Dialkyl Tetraethers (OH-isoGDGTs), such as %OH, RI-OH, RI-OH′ and OHC, have shown potential for reconstructing past changes. However, progress has been limited by the lack of a global core-top calibration with ample geographical coverage. Here, we compile an extensive surface sediment dataset OH-isoGDGTs well regular GDGTs (isoGDGTs), both data generated at NIOZ (n = 575) previously published from other laboratories 297). We find interlaboratory differences proxy indices that incorporate isoGDGTs, indicating care must be taken in compiling large GDGT datasets multiple laboratories. Our results confirm strong signal isoGDGT distribution, especially OH-isoGDGT-0 non-hydroxylated but also reveal water depth might impact distribution 1 2 cyclopentane moieties. This will affect RI-OH indices, particularly tropical regions, where occurs low abundance. explore new combine dependence OH-isoGDGT distributions propose use TEX86OH, which includes denominator TEX86 index. modification leads to much higher sensitivity index, regions annual mean sea temperatures between 5 15 °C. Application this novel paleothermometer polar core suggests is likely result more reliable reconstructions are abundant.

Language: Английский

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The Novel Hydroxylated Tetraether Index RI‐OH′ as a Sea Surface Temperature Proxy for the 160‐45 ka BP Period Off the Iberian Margin

Paleoceanography and Paleoclimatology, Journal Year: 2021, Volume and Issue: 36(3)

Published: Feb. 20, 2021

Abstract RI‐OH′ and RI‐OH (ring index of hydroxylated tetraethers) are two novel organic paleothermometers which could either complement or replace more established paleothermometric proxies, such as U K ′ 37 (C ketone unsaturation ratio) TEX 86 (TetraEther indeX tetraethers consisting carbon atoms). Despite a few promising attempts, the potential is not fully constrained. Here we present new high‐resolution temperature records over 160‐45 ka BP (before = year 1950 CE) period using four proxies (RI‐OH′, RI‐OH, , ) from three deep sea sediment cores located in north‐south transect along Iberian Margin. We analyzed all single set lipid extracts to optimize proxy‐proxy comparisons phase relationship studies. responds Dansgaard‐Oeschger Heinrich events, better resembles than influence (sub)polar waters during events does RI‐OH. While gives realistic surface temperatures latitudinal gradients coherent with those independent paleothermometers, extensive RI‐OH′‐temperature calibration for North Atlantic clearly needed. However, absence significant warm bias RI‐OH′‐based compared shallow site suggests that endemic, deep‐dwelling archeal communities affect but leads Heinrich‐like potentially due background fluxes nonhydroxylated summed primary productivity dependent investigated classes. Relationships Greenland further support paleothermometry.

Language: Английский

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Biomarker characterization of the North Water Polynya, Baffin Bay: implications for local sea ice and temperature proxies

Biogeosciences, Journal Year: 2023, Volume and Issue: 20(1), P. 229 - 249

Published: Jan. 16, 2023

Abstract. The North Water Polynya (NOW, Inuktitut: Sarvarjuaq; Kalaallisut: Pikialasorsuaq), Baffin Bay, is the largest polynya and one of most productive regions in Arctic. This area thin to absent sea ice a critical moisture source for local sheet sustenance and, coupled with inflow nutrient-rich Arctic Surface Water, supports diverse community fauna indigenous people. Although paleoceanographic records provide important insight into NOW's past behavior, it that we better understand modern functionality proxies. In this study, analyzed lipid biomarkers, including algal highly branched isoprenoids sterols extent pelagic productivity archaeal glycerol dibiphytanyl tetraethers (GDGTs) ocean temperature, set surface sediment samples from within around NOW. conjunction previously published datasets, our results show all exhibit strong correlations each other not sterols, which suggests spring or autumn diatom (HBIs) rather than combination open-water diatoms as seen elsewhere Sterols are also concentrated NOW statistically higher concentrations here compared sites south NOW, consistent order magnitude primary observed relative surrounding waters summer months. Finally, temperature calibrations GDGTs OH-GDGTs reduce uncertainty present global but identify some additional variables may be controlling their distribution, such nitrate availability dissolved oxygen. Collectively, analyses new utility these biomarker proxies high-latitude settings will help refined perspective on development application downcore reconstructions.

Language: Английский

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Archaeal Hydroxylated Isoprenoid GDGTs in Asian Lake Sediments: A New Tool for Terrestrial Paleotemperature Reconstructions

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(6)

Published: March 18, 2024

Abstract Hydroxylated isoprenoid GDGTs (OH‐GDGTs) have emerged as a novel tool for reconstructing sea surface temperatures. However, when using marine OH‐GDGT calibration in lacustrine settings, it leads to significant overestimation of temperatures, emphasizing the necessity thorough examination OH‐GDGTs lakes. Here, we investigated distributions sediments from 65 lakes West China and compiled published Asian lake global data sets. Among all GDGT‐based indices, RI‐OH showed strongest correlation with temperature across The value was higher than sediments, likely due differences composition Group 1.1a thaumarchaeotal species between two settings. first developed addressed issue applied both water column sediment core, highlighting potential new terrestrial paleothermometer.

Language: Английский

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OH-isoGDGTs as paleothermometer to bottom seawater temperature in the eastern China marginal seas

Chemical Geology, Journal Year: 2025, Volume and Issue: unknown, P. 122768 - 122768

Published: April 1, 2025

Language: Английский

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Impact of terrestrial organic matter input on distributions of hydroxylated isoprenoidal GDGTs in marine sediments: Implications for OH-isoGDGT-based temperature proxies

Organic Geochemistry, Journal Year: 2025, Volume and Issue: unknown, P. 105010 - 105010

Published: April 1, 2025

Language: Английский

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