Arctic Ocean 50KYr Ostracod Mg/Ca-Sr/Ca Intermediate Water Paleotemperatures Cronin, T.M.; Dwyer, G.S.; Farmer, J.R.; Bauch, H.A.; Spielhagen, R.F.; Jakobsson, M.; Nilsson, J.; Briggs, W.M.; Stepanova, A. Cronin, T.M. Dwyer, G.S. Farmer, J.R. Bauch, H.A. Spielhagen, R.F. Jakobsson, M. Nilsson, J. Briggs, W.M. Stepanova, A. Arctic earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,PS1243-Species glac= K. glacialis min= K. minima) earth science/paleoclimate/climate reconstructions|paleoceanography (sea water temperature,magnesium/calcium,null,degree Celsius,null,climate reconstructions|paleoceanography,null,null,N,bottom water temperature) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (sodium/calcium,ostracod,null,millimole per mole,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (strontium/calcium,ostracod,null,millimole per mole,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,PS1243-MgGlac&Min-Corr for Krithe minima corrected for species effect (0.77 x original Mg/Ca ratio)) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Krithe Species) earth science/paleoclimate/paleoceanography (magnesium/calcium,ostracod,null,millimole per mole,null,paleoceanography,corrected,null,N,corrected for species effect (0.77 x original Mg/Ca ratio)) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Krithe Species glac= K. glacialis min= K. minima) earth science/paleoclimate/paleoceanography (collection water depth,null,null,meter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,PS1243 Age) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,PS1243-3-PtSmooth) earth science/paleoclimate/paleoceanography (magnesium/calcium,ostracod,null,millimole per mole,null,paleoceanography,smoothed,null,N,null) earth science/paleoclimate/paleoceanography (strontium/calcium,ostracod,null,millimole per mole,null,paleoceanography,smoothed,null,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,N,Visual Preservation Index: 1 = translucent best preservation 7 = chalky worst preservation) earth science/paleoclimate/paleoceanography (magnesium/calcium,ostracod,null,millimole per mole,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Core Name Central Arctic Composite Core) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Core Name) earth science/paleoclimate/paleoceanography (depth,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (Pl-94AR-BC06B>LATITUDE 75.35>LONGITUDE -170.5) (Pl-94AR-BC28>LATITUDE 88.87>LONGITUDE 140.18) (PS1243-1/2>LATITUDE 69.38>LONGITUDE -6.53) In the Arctic Ocean, the cold and relatively fresh water beneath the sea ice is separated from the underlying warmer and saltier Atlantic Layer by a halocline. Ongoing sea ice loss and warming in the Arctic Ocean have demonstrated the instability of the halocline, with implications for further sea ice loss. The stability of the halocline through past climate variations is unclear. Here we estimate intermediate water temperatures over the past 50,000 years from the Mg/Ca and Sr/Ca values of ostracods from 31 Arctic sediment cores. From about 50 to 11 kyr ago, the central Arctic Basin from 1,000 to 2,500 m was occupied by a water mass we call Glacial Arctic Intermediate Water. This water mass was 1-2°C warmer than modern Arctic Intermediate Water, with temperatures peaking during or just before millennial-scale Heinrich cold events and the Younger Dryas cold interval. We use numerical modelling to show that the intermediate depth warming could result from the expected decrease in the flux of fresh water to the Arctic Ocean during glacial conditions, which would cause the halocline to deepen and push the warm Atlantic Layer into intermediate depths. Although not modelled, the reduced formation of cold, deep waters due to the exposure of the Arctic continental shelf could also contribute to the intermediate depth warming. STUDY NOTES: Quaternary Arctic Ocean Ostracode Mg/Ca and Sr/Ca ratios and Paleotemperature estimates NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Cronin, T.M. Investigator : Dwyer, G.S. Investigator : Farmer, J.R. Investigator : Bauch, H.A. Investigator : Spielhagen, R.F. Investigator : Jakobsson, M. Investigator : Nilsson, J. Investigator : Briggs, W.M. Investigator : Stepanova, A. 2012-12-19 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13668 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2012/cronin2012bwt.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2012/cronin2012mgca.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2012/cronin2012bwt.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2012/cronin2012mgca.txt English https://www.ncdc.noaa.gov/paleo/study/13668 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2012/cronin2012bwt.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2012/cronin2012mgca.txt T.M. Cronin, G.S. Dwyer, J. Farmer, H.A. Bauch, R.F. Spielhagen, M. Jakobsson, J. Nilsson, W.M. Briggs Jr and A. Stepanova. 2012. Deep Arctic Ocean warming during the last glacial cycle. Nature Geoscience, Vol. 5, No. 9, pp. 631-634. DOI: 10.1038/ngeo1557 START YEAR: 50000 cal yr BP * END YEAR: 0 cal yr BP -170.5 69.38 140.18 88.87