History of sea ice in the Arctic

• Published in: Quaternary Science Reviews
• Main Authors: Polyak, L, Alley, R. B, Andrews, J. T, Brigham-Grette, J, Cronin, TM, Darby, D. A., Dyke, A. S., Fitzpatrick, J. J., Funder, S., Holland, M, Jennings, A. E., Miller, G. H., O'Regan, Matthew, Savelle, J., Serreze, M., St John, K., White, J. W. C., Wolff, E.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2010
• Subjects: QE Geology; Arctic; Sea ice
• Online Access: https://orca.cardiff.ac.uk/id/eprint/7539/; https://doi.org/10.1016/j.quascirev.2010.02.010

Arcticsea-ice eextentandvolumearedecliningrapidly.SeveralstudiesprojectthattheArcticOceanmay becomeseasonallyice-freebytheyear2040orevenearlier.Puttingthisintoperspectiverequiresinfor- mationonthehistoryofArcticsea-iceconditionsthroughthegeologicpast.Thisinformationcanbeprovided byproxyrecordsfromtheArcticOceanfloorandfromthesurroundingcoasts.Althoughexistingrecordsare farfromcomplete,theyindicatethatseaicebecameafeatureoftheArcticby47Ma,followingapronounced declineinatmosphericpCO2 afterthePaleocene–EoceneThermalOptimum,andconsistentlycoveredat leastpartoftheArcticOceanfornolessthanthelast13–14millionyears.Icewasapparentlymostwide- spreadduringthelast2–3millionyears,inaccordancewithEarth’soverallcoolerclimate.Nevertheless, episodesofconsiderablyreducedseaiceorevenseasonallyice-freeconditionsoccurredduringwarmer periodslinkedtoorbitalvariations.Thelastlow-iceeventrelatedtoorbitalforcing(highinsolation)wasin theearlyHolocene,afterwhichthenorthernhighlatitudescooledoverall,withsomesuperimposedshorter- term(multidecadaltomillennial-scale)andlower-magnitudevariability.ThecurrentreductioninArcticicecoverstartedinthelate19thcentury,consistentwiththerapidlywarmingclimate,andbecameverypronouncedoverthelastthreedecades.Thisicelossappearstobeunmatchedoveratleastthelastfewthousandyearsandunexplainablebyanyoftheknownnaturalvariabilities.