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Fennoscandian freshwater control on Greenland hydroclimate shifts at the onset of the Younger Dryas.

Muschitiello F, Pausata FS, Watson JE, Smittenberg RH, Salih AA, Brooks SJ, Whitehouse NJ, Karlatou-Charalampopoulou A, Wohlfarth B - Nat Commun (2015)

Bottom Line: Transient climate model simulations forced with FIS freshwater reproduce the initial hydroclimate dipole through sea-ice feedbacks in the Nordic Seas.The transition is attributed to the export of excess sea ice to the subpolar North Atlantic and a subsequent southward shift of the westerly winds.We suggest that North Atlantic hydroclimate sensitivity to FIS freshwater can explain the pace and sign of shifts recorded in Greenland at the climate transition into the Younger Dryas.

View Article: PubMed Central - PubMed

Affiliation: Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, SE-10691 Stockholm, Sweden.

ABSTRACT
Sources and timing of freshwater forcing relative to hydroclimate shifts recorded in Greenland ice cores at the onset of Younger Dryas, ∼12,800 years ago, remain speculative. Here we show that progressive Fennoscandian Ice Sheet (FIS) melting 13,100-12,880 years ago generates a hydroclimate dipole with drier-colder conditions in Northern Europe and wetter-warmer conditions in Greenland. FIS melting culminates 12,880 years ago synchronously with the start of Greenland Stadial 1 and a large-scale hydroclimate transition lasting ∼180 years. Transient climate model simulations forced with FIS freshwater reproduce the initial hydroclimate dipole through sea-ice feedbacks in the Nordic Seas. The transition is attributed to the export of excess sea ice to the subpolar North Atlantic and a subsequent southward shift of the westerly winds. We suggest that North Atlantic hydroclimate sensitivity to FIS freshwater can explain the pace and sign of shifts recorded in Greenland at the climate transition into the Younger Dryas.

No MeSH data available.


Related in: MedlinePlus

Comparison between Greenland and Hässeldala hydrological proxies at the onset of the YD pollen zone.Synchronized (a) NGRIP d-excess22 and (b) GRIP snow accumulation23 records compared to Hässeldala (c) δDaq corrected for ice volume, temperature and post-glacial isostatic uplift changes (δDcorr; Supplementary Methods), and (d) terrestrial evapotranspiration. The δDcorr is a proxy for δD of precipitation reflecting anomalies in distillation of the water vapour at the marine moisture source25, primarily driven by input of isotopically depleted freshwater. Note that the ∼19‰ decrease in δDcorr (∼2.4‰ decrease in δ18O) during the late Allerød pollen zone is in agreement with a −2.5‰ shift in δ18O recorded in benthic foraminifera off the west coast of Southern Sweden46. The temporal evolution of the regional hydrological conditions is also displayed. Greenland records are presented at 20-year resolution with bold lines indicating the 60- year moving average. All records are presented with shadings indicating empirical 68% uncertainty bounds based on analytical and age-model errors. Vertical axes are oriented such that dry conditions plot upwards (note reverse axis for GRIP accumulation). Shown is also the combined probability of a number of calibrated radiocarbon dates constraining the age of the first drainage of the Baltic Ice Lake, inferred from deglaciation of the outlet in south-central Sweden and rapid isolation of lakes in the outlet area at Mt. Billingen (Supplementary Methods). 68% uncertainty (bar) and median age (circle) are also presented. Records are consistently displayed on the same IntCal13 time scale.
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f3: Comparison between Greenland and Hässeldala hydrological proxies at the onset of the YD pollen zone.Synchronized (a) NGRIP d-excess22 and (b) GRIP snow accumulation23 records compared to Hässeldala (c) δDaq corrected for ice volume, temperature and post-glacial isostatic uplift changes (δDcorr; Supplementary Methods), and (d) terrestrial evapotranspiration. The δDcorr is a proxy for δD of precipitation reflecting anomalies in distillation of the water vapour at the marine moisture source25, primarily driven by input of isotopically depleted freshwater. Note that the ∼19‰ decrease in δDcorr (∼2.4‰ decrease in δ18O) during the late Allerød pollen zone is in agreement with a −2.5‰ shift in δ18O recorded in benthic foraminifera off the west coast of Southern Sweden46. The temporal evolution of the regional hydrological conditions is also displayed. Greenland records are presented at 20-year resolution with bold lines indicating the 60- year moving average. All records are presented with shadings indicating empirical 68% uncertainty bounds based on analytical and age-model errors. Vertical axes are oriented such that dry conditions plot upwards (note reverse axis for GRIP accumulation). Shown is also the combined probability of a number of calibrated radiocarbon dates constraining the age of the first drainage of the Baltic Ice Lake, inferred from deglaciation of the outlet in south-central Sweden and rapid isolation of lakes in the outlet area at Mt. Billingen (Supplementary Methods). 68% uncertainty (bar) and median age (circle) are also presented. Records are consistently displayed on the same IntCal13 time scale.

Mentions: The comparison of HÄ δDcorr and ΔδDterr-aq records with NGRIP d-excess and GRIP accumulation rates shows two separate phases during GI-1a and during the first ∼180 years of GS-1 (Fig. 3). Each of these are characterized by a hydroclimate dipole across the eastern North Atlantic. GI-1a is marked by increasingly fresher North Sea surface conditions and inhibited moisture transport to HÄ. This interval coincides with a progressive north-eastward shift of the North Atlantic source of Greenland precipitation (more proximal) and with enhanced moisture transport to the summit24.


Fennoscandian freshwater control on Greenland hydroclimate shifts at the onset of the Younger Dryas.

Muschitiello F, Pausata FS, Watson JE, Smittenberg RH, Salih AA, Brooks SJ, Whitehouse NJ, Karlatou-Charalampopoulou A, Wohlfarth B - Nat Commun (2015)

Comparison between Greenland and Hässeldala hydrological proxies at the onset of the YD pollen zone.Synchronized (a) NGRIP d-excess22 and (b) GRIP snow accumulation23 records compared to Hässeldala (c) δDaq corrected for ice volume, temperature and post-glacial isostatic uplift changes (δDcorr; Supplementary Methods), and (d) terrestrial evapotranspiration. The δDcorr is a proxy for δD of precipitation reflecting anomalies in distillation of the water vapour at the marine moisture source25, primarily driven by input of isotopically depleted freshwater. Note that the ∼19‰ decrease in δDcorr (∼2.4‰ decrease in δ18O) during the late Allerød pollen zone is in agreement with a −2.5‰ shift in δ18O recorded in benthic foraminifera off the west coast of Southern Sweden46. The temporal evolution of the regional hydrological conditions is also displayed. Greenland records are presented at 20-year resolution with bold lines indicating the 60- year moving average. All records are presented with shadings indicating empirical 68% uncertainty bounds based on analytical and age-model errors. Vertical axes are oriented such that dry conditions plot upwards (note reverse axis for GRIP accumulation). Shown is also the combined probability of a number of calibrated radiocarbon dates constraining the age of the first drainage of the Baltic Ice Lake, inferred from deglaciation of the outlet in south-central Sweden and rapid isolation of lakes in the outlet area at Mt. Billingen (Supplementary Methods). 68% uncertainty (bar) and median age (circle) are also presented. Records are consistently displayed on the same IntCal13 time scale.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660357&req=5

f3: Comparison between Greenland and Hässeldala hydrological proxies at the onset of the YD pollen zone.Synchronized (a) NGRIP d-excess22 and (b) GRIP snow accumulation23 records compared to Hässeldala (c) δDaq corrected for ice volume, temperature and post-glacial isostatic uplift changes (δDcorr; Supplementary Methods), and (d) terrestrial evapotranspiration. The δDcorr is a proxy for δD of precipitation reflecting anomalies in distillation of the water vapour at the marine moisture source25, primarily driven by input of isotopically depleted freshwater. Note that the ∼19‰ decrease in δDcorr (∼2.4‰ decrease in δ18O) during the late Allerød pollen zone is in agreement with a −2.5‰ shift in δ18O recorded in benthic foraminifera off the west coast of Southern Sweden46. The temporal evolution of the regional hydrological conditions is also displayed. Greenland records are presented at 20-year resolution with bold lines indicating the 60- year moving average. All records are presented with shadings indicating empirical 68% uncertainty bounds based on analytical and age-model errors. Vertical axes are oriented such that dry conditions plot upwards (note reverse axis for GRIP accumulation). Shown is also the combined probability of a number of calibrated radiocarbon dates constraining the age of the first drainage of the Baltic Ice Lake, inferred from deglaciation of the outlet in south-central Sweden and rapid isolation of lakes in the outlet area at Mt. Billingen (Supplementary Methods). 68% uncertainty (bar) and median age (circle) are also presented. Records are consistently displayed on the same IntCal13 time scale.
Mentions: The comparison of HÄ δDcorr and ΔδDterr-aq records with NGRIP d-excess and GRIP accumulation rates shows two separate phases during GI-1a and during the first ∼180 years of GS-1 (Fig. 3). Each of these are characterized by a hydroclimate dipole across the eastern North Atlantic. GI-1a is marked by increasingly fresher North Sea surface conditions and inhibited moisture transport to HÄ. This interval coincides with a progressive north-eastward shift of the North Atlantic source of Greenland precipitation (more proximal) and with enhanced moisture transport to the summit24.

Bottom Line: Transient climate model simulations forced with FIS freshwater reproduce the initial hydroclimate dipole through sea-ice feedbacks in the Nordic Seas.The transition is attributed to the export of excess sea ice to the subpolar North Atlantic and a subsequent southward shift of the westerly winds.We suggest that North Atlantic hydroclimate sensitivity to FIS freshwater can explain the pace and sign of shifts recorded in Greenland at the climate transition into the Younger Dryas.

View Article: PubMed Central - PubMed

Affiliation: Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, SE-10691 Stockholm, Sweden.

ABSTRACT
Sources and timing of freshwater forcing relative to hydroclimate shifts recorded in Greenland ice cores at the onset of Younger Dryas, ∼12,800 years ago, remain speculative. Here we show that progressive Fennoscandian Ice Sheet (FIS) melting 13,100-12,880 years ago generates a hydroclimate dipole with drier-colder conditions in Northern Europe and wetter-warmer conditions in Greenland. FIS melting culminates 12,880 years ago synchronously with the start of Greenland Stadial 1 and a large-scale hydroclimate transition lasting ∼180 years. Transient climate model simulations forced with FIS freshwater reproduce the initial hydroclimate dipole through sea-ice feedbacks in the Nordic Seas. The transition is attributed to the export of excess sea ice to the subpolar North Atlantic and a subsequent southward shift of the westerly winds. We suggest that North Atlantic hydroclimate sensitivity to FIS freshwater can explain the pace and sign of shifts recorded in Greenland at the climate transition into the Younger Dryas.

No MeSH data available.


Related in: MedlinePlus