Advances in Environmental and Agricultural Science

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1 Arctic se ice extent in chnging climte GENRIKH ALEKSEEV, NATALIA GLOK, ALEXANDER SMIRNOV Arctic nd Antrctic Reserch Institute Bering str. 38, St.-Petersurg RUSSIA Astrct: - An increse in surfce ir temperture (SAT) nd reduced se ice extent (SIE) in the Arctic develop with high degree of greement in the summer seson. On this sis it is proposed index for mesuring SIE chnge which is the summer SAT in the mrine Arctic tht is defined s the mximl Arctic wter re covered with ice in winter. Correltion etween summer SAT nd Septemer SIE sed on dt from 1980 to 2013 is On this sis the nomlies of Arctic Septemer SIE ws restored strted from Restored SIE showed significnt decrese in s with minimum in 1936 which, however, ccounted for hlf of the minimum in Impct of the inflow of wrm nd slty Atlntic wter on distriution in winter SIE in the Brents Se is considered. It is estlished incresed ir temperture trend in lte utumn nd erly winter, when the tmosphere gin the het from the ice-free res, which grow with the development of wrming. The close reltionship etween the increse in summer ir tempertures nd reduced ice re in Septemer used to ssess the onset of summer Arctic ice disppering. Key-Words: - Arctic, climte, se ice, surfce ir temperture, Brents Se, Atlntic wter, ice disppernce 1 Introduction The erliest systemtic informtion out rctic se ice is ville for the Atlntic region of the Arctic Ocen since the twentieth century [6, 18, 27, 30]. The first se ice chrts hve een prepred in the Dnish Meteorologicl Institute sed on ship oservtions in the Greenlnd nd Brents Ses mostly collected in spring nd summer months (i.e., from April to August). Growth of shipping long the cost of Sieri occurred in the 1930s results in extension of se ice oservtions towrd the Sierin Arctic ses. Since then ircrft-sed surveys ecome the primry source of ice oservtions typiclly presented in form of ice chrts. The ice chrts produced for the period since 1933 re n importnt prt of the historicl rchive, which ws collected in Arctic nd Antrctic Reserch Institute [3, 11], nd successfully used to prepre historicl ice series for the Arctic ses [19]. The erliest historicl dt out the se ice in the Brents nd Sierin Arctic ses were collected since 1924 [7-9, 31] from vrious sources. The longest dtset strts in 1870 [21] nd covers the ocens with resolution of 1 x 1 [10]. Historicl Arctic se ice dt in this dtset were tken from [4], nd cover the period since 1901 [13]. Another long-term se ice dtset cn e found t [11]. Anlysis of historicl se ice dt hd een crried out mny times using continuously growing ville oservtions. Dt showed significnt long-term chnges in ice distriutions. Zkhrov [31] reported four stges in the development of the Arctic se ice cover occurred in the twentieth century: two stges of expnsion ( nd ), nd two stges of ice cover reduction ( nd ), expressed on ckground of the seculr decline of se ice extent. According to Vinje [27] the se ice extent in the Greenlnd nd Brents Ses in April stedily declined since 1864, nd in 1998 ws reduced y 33%. Comprison of historicl ice series from vrious sources shows significnt differences etween them nd rpid disppernce fter trnsition to stellite oservtions [1] - the min tool for se ice monitoring since Assessments of se ice oservtions from stellites show reduction of the se ice extent, which ws ccelerted over the pst two decdes [2, 5, 7, 15-17, 23, 25, 26]. Presence or sence of the significnt Arctic se ice reduction during the first wrming of the Arctic in the 1930s is suject for discussion [22]. The uthors conducted experiments with glol tmospheric circultion model with prescried se ice oundries nd concentrtion tken from HdSST dtset. The results did not show the wrming in the Arctic in the 1930s, while the wrming ws developed when the se ice in the model is reduced. In this connection it is interesting to estimte the stte of se ice in the Arctic in the 1930s, when the wrming in the Arctic hs een oserved. Some indictions of the reduced ice extent in the 1930s re discussed in ppers [28, 29], written ISBN:

2 directly in the period of the development of the first Arctic wrming. Our pper presents n evlution of the pst nd future chnges in se ice in the twenty nd twenty-first centuries nd their interreltion with other components of the Arctic climte system on sis of se ice, ir nd wter temperture oservtions in the Arctic nd the Northern Hemisphere. 2 Dt Se ice dt re presented y the se ice index (the verge of se ice extent in the Arctic since 1978, in millions sq. km) tken from the NSIDC site [13]. The verge se ice extent dt hve een collected since 1924, nd cn e found t the AARI wesite [11]. The verge monthly ir tempertures for the Arctic meteorologicl sttions re derived from dt rchive surfce meteorology in the North Polr Region, which ws prepred in AARI, nd from the NCEP/NCAR renlysis [12]. The se surfce temperture (SST) is tken from the HdSST dtset [10]. The verge Atlntic wter tempertures in the m lyer t the Kol section (33 30 E) in the Brents Se re tken from the PINRO wesite [14]. c 3 Discussion 3.1 An empiricl ssessment of externl influences nd feedcks on reduction of the Arctic SIE There re mny resons responsile for the mplifiction of the wrming nd decline of se ice extent (SIE) in the Arctic. The primry reson, in our opinion, is n increse of het nd moisture trnsports into the northern polr region, which triggers feedcks in the Arctic climte system nd ccelertes the wrming nd degrdtion of the SIE. The Arctic wrming ws evident s n increse of surfce ir temperture (SAT). Air temperture chnges in the mrine Arctic, which is defined s the Arctic wter re with presence of se ice in winter [2], primrily ffect the growth of ice cover in winter nd its melting in summer. To estimte the verge ir temperture in this re we used records of 41 sttions with oservtions strted not lter thn in These sttions were locted on islnds nd t the cost of the Arctic Ocen (Fig. 1), from which the summer Arctic se ice retret egins. Fig. 1. Averge surfce ir temperture in winter (), in summer (c) t meteorologicl sttions in the mrine Arctic () during Dotted line shows 6 th order polynomil pproximtion. Fig. 1 shows rpid growth of summer SAT since 1996 with n solute mximum in The winter tempertures efore 1991 nd the summer tempertures efore 1996 hd wek negtive trends, which chnged to significnt positive trends for the period fter these yers. In full ccordnce with rpid growth of summer ir tempertures, the shrinking of the se ice extent in the end of summer ws ccelerted (Fig. 2), nd reched its solute minimum in The correltion coefficient etween the chnges of summer ir temperture in the mrine Arctic nd Septemer se ice extent equls to -0.93, suggesting tht the summer SAT cn e considered s n integrl indictor (or index) of externl influences on the SIE. ISBN:

3 Fig. 2. (1) The verge Arctic se ice extent in Septemer tken from NSIDC site [13]. (2) The verge surfce ir temperture in summer (JJA) in the mrine Arctic (temperture scle is inverted). R is correltion coefficient etween (1) nd (2) for Vlue in rckets is correltion coefficient etween the residuls of (1) nd (2) with qudrtic polynomil pproximtions. Dependence of the Septemer SIE from the summer SAT decresed in the Sierin Arctic ses under influence of se ice dynmics. The correltion etween the summer SAT nd Septemer SIE in those ses is chrcterized y the coefficient of for This correltion is responsile for ~60% of the vriility of the Septemer SIE. The rest of SIE vriility is ccounted y ice dynmics induced y impct of winds nd currents, which form ice mssifs res of compct ice spreding out of the Arctic Bsin. 3.2 Reconstruction of the pst Arctic SIE sed on the temperture index Tking into ccount strong reltionship etween the summer SAT nd the Arctic SIE, the stte of Septemer SIE in previous yer cn e estimted. Unfortuntely, most of the wether sttions in the mrine Arctic egn their work fter 1950, nd just seven of them were operted until the eginning of the 20th century (Fig. 3). The correltion etween the summer tempertures t these sttions nd the Arctic SIE in Septemer over equls to The reconstruction of the Septemer SIE for the pst yers sed on the regression model etween the SAT nd SIE shows (Fig. 3) significnt SIE decrese in , which is close to the Viese s estimte [28], who found decrese out 1 million km 2. However, the strongest reconstructed SIE reduction for s, occurred in 1936, equls to only hlf of the ice reduction in Fig. 3. () Positions of seven meteorologicl sttions in the mrine Arctic with collected oservtions since 1900; () 1 reconstructed Septemer SIE in the Arctic from 1900 to oserved SIE for Influence of the ocen on winter se ice distriution In spite of the fct tht the winter SAT increses fster thn the summer SAT, the reduction of winter SIE in the Arctic is much slower in comprison with summer shrinking. One of the resons is tht the Arctic ses in winter re completely covered with ice. Therefore, chnges in the Arctic winter SIE re ssocited with shift in the se ice edge in the Nordic Ses nd the Northwestern Atlntic tht is determined y the oundry etween the Arctic wter nd the slt nd wrm Atlntic wter [32, 33]. Vritions of winter SIE include the component determined y chnges of the Atlntic Wter (AW) inflow nd y the shift of AW distriution in the Nordic Ses nd the Northwestern Atlntic. An influence of this component on the winter SIE is clerly evident in the Brents Se from longterm historicl dtsets of SIE, AW tempertures t the Kol section, nd se surfce temperture (SST). For exmple, Tle 1 contins correltion coefficients etween the SIE, AW temperture, nd SST in the Brents Se derived for ISBN:

4 Tle 1.Correltion coefficients etween the men nnul AW temperture in m lyer long the Kol section, HdSST in the Brents Se, nd the monthly SIE in the Brents Se for (95% level of significnce of the coefficients is 0.21) Months T AW -0,54-0,64-0,59-0,66-0,79-0,75-0,67-0,56-0,47-0,37-0,34-0,51 SST -0,52-0,62-0,65-0,75-0,80-0,79-0,74-0,67-0,57-0,48-0,33-0,47 The correltion of the monthly men AW temperture t the Kol section nd SIE for reches its mximl vlue of 0.86 in My (Tle 2). Shift of the correltion mximum to My cn e explined y significnt impct of AW inflow occurred in southern prt of the Brents Se tht prevents the southwrd spreding of se ice edge. A correspondence etween distriutions of the AW nd the se ice in the Brents Se cn e seen from fig. 4, showing similr sptil pttern of surfce slinity distriution nd se ice edge in June of 1969 nd In June 1969 the slty AW occupies smller re, nd se ice goes further to south in comprison with June Tle 2. Correltion coefficients etween the monthly men AW temperture in m lyer long the Kol section nd the monthly SIE in the Brents Se for (95% level of significnce of the coefficients is 0.26) Months T AW -0,68-0,70-0,68-0,77-0,86-0,77-0,59-0,47-0,41-0,30-0,40-0, Effect of summer SIE reduction on winter ir temperture in the Arctic One of feedcks tht mplify the wrming in the Arctic is the result of summer SIE reduction, which increses the ir temperture in lte utumn nd erly winter (Fig. 5). In the period with negtive ir tempertures, the het ccumulted in ice-free res releses to the tmosphere. An dditionl contriution to the wrming is due to increse of the wter vpor content in the ir surfce lyer, ccompnied y incresed downwrd long-wve rdition. Fig. 5. Trend of the monthly men SAT in the mrine Arctic for Period of ws chosen s period of rpid SAT increse. The lrgest vlues of SAT trends occur from Octoer through Ferury, exceeding ckground vlue (verge for Mrch-Septemer), nd contriute up to 75% to mplifiction of the trend cused y this feedck. Fig. 4. Se surfce slinity nd the se ice edge in the Brents Se in June 1969 () nd 1987 ().Se surfce slinity is tken from the digitl Climtologicl Atls of the Nordic Ses nd Northern North Atlntic issued y NOAA in the Interntionl Ocen Atls nd Informtion Series in Ice edge position (lck curve) is tken from HdSST dtset. 3.5 Summer se ice disppernce The close reltionship etween the summer ir temperture nd reduced ice re in Septemer (Fig. 3) llows predicting the evolution of Septemer SIE using sttisticl modeling. According to the elorted sttisticl model the rctic summer se ice cn disppers in the middle of the 2030s. The dte of disppernce of the summer ice cover cn e estimted using simple extrpoltion of the Septemer SIE record, suggesting roustness of the estimtes in cse of ISBN:

5 coincidence of the results in oth predictions. Fig. 6 shows the result of pplying oth methods for prediction of the time of the summer SIE disppernce. c Fig. 6: () 2-nd degree polynomil extrpoltion of the SIE in Septemer (coeff. determintion is 0.78); () extrpoltion of reltionships etween the summer tempertures nd SIE in Septemer (coeff. determintion for liner model is 0.85; for qudrtic model is 0.89); (c) qudrtic extrpoltion of the summer ir temperture (coeff. determintion is 0.65), indicting chievement of 7.1 nd 8.4 C out 2027 nd 2038, respectively. Derived empiricl estimtes include influence of oth nthropogenic nd nturl fctors, ffecting the rpid decline of summer ice in the Arctic. They show possile disppernce of the se ice in Septemer in the middle 2030s. This prediction is found in rnge of the erliest disppernce of Septemer se ice, estimted from glol climte models [20]. 4 Conclusion We propose to use summer SAT in the mrine Arctic s predictor for estimtes of Septemer SIE chnges. The mrine Arctic is defined s the re of the Arctic, which is covered with se ice in winter. The correltion coefficient etween the summer SAT nd the Arctic SIE in Septemer equls to for Bsed on this correltion, Septemer SIE nomlies were reconstructed for The reconstructed SIE dtset shows significnt reduction in s with minimum of ice extent registered in However, it ws just hlf of the reduction found in The close reltionship etween the increse of summer ir temperture nd the reduction of Septemer SIE is used to ssess the onset of summer Arctic ice disppernce. Remining the current rte of wrming of ir temperture we found tht such n event cn hppen s erly s the middle of 2030s. An impct of se ice dynmics on Septemer SIE vriility is evident in the Sierin Arctic ses, where out 40% of the SIE vriility is governed y winds nd currents. Chnges of the Arctic winter SIE re ssocited with shift in the se ice edge in the Nordic Ses nd in the Northwestern Atlntic, which is determined y the oundry etween the Arctic wter nd the slt nd wrm Atlntic wter. An impct of the inflow of the wrm nd sline Atlntic wter nd shift of AW distriution on the winter SIE is evident in the Brents Se. The correltion coefficient etween the monthly Atlntic wter tempertures nd SIE in the winter/spring months reches to in My. We rgue the shift of highest negtive correltion to My y significnt influence of the AW inflow, which prevents the southwrd spreding of se ice edge in the Brents Se. The lrgest positive trends were found in surfce ir temperture in the mrine Arctic during the lst decde re were oserved in the lte utumn nd erly winter, when the het ccumulted in ice free wter res releses to the tmosphere. This process is responsile for up to 75% of the trend in this period. This reserch hs een supported y the Ministry of Eduction nd Science of the Russin Federtion project RFMEFI61014X0006 nd the Russin Foundtion for Bsic Reserch grnt А. ISBN:

6 References: 1. Alekseev G.V., Kuzmin S.I., Ngurny A.P., Ivnov N.E. Arctic se ice dt sets in the context of the climte chnge during the 20th century. Climte vriility nd extremes during the pst 100 yers // Series: Advnces in Glol Chnge Reserch, V.33, 2007, pp Alekseev, G.V., Dnilov A.I., V.M. Kttsov, S.I. Kuzmin, nd N.E. Ivnov: Chnges in the climte nd se ice of the Northern hemisphere in the 20th nd 21st centuries from dt of oservtion nd modeling // Izvesti of Russin Acdemy of Sciences: Physics of Atmosphere nd Ocen, 45, 6, 2009, pp Borodchev V.E., Shilnikov V.I. History of eril surveys in the Russin Arctic. SP.: Gidrometeoizdt, Chpmn W.L. nd Wlsh J.E. Recent vritions of se ice nd ir temperture in high ltitudes // Bull. Amer. Meteorol. Soc. 74, 1993, pp Comiso J.C., Prkinson C.L., Gersten R., Stock L. Accelerted decline in the Arctic se ice cover // Geophys. Res. Lett. 35, L01703, 2008, doi: /2007gl Divine D.V., Dick C. Historicl vriility of se ice edge position in the Nordic Ses // J. Geophys. Res., 111, C01001, 2006, doi: /2004jc Frolov I.E. (ed.) Ocenogrphy nd se ice. Ser. "Russin contriution to the Interntionl Polr Yer M. SP: Pulsen. 2011, P Frolov I.E., Gudkovich Z.M., Krklin V.P., Kovlev E.G., Smolynitskiy V.M. Climtic chnges of the ice cover of the ses of the Eursin continentl shelf, SP: Nuk, 2007, P Frolov I.E., Gudkovich Z.M., Rdionov V.F., Timohov L.A., Shirochkov A.V. Scientific investigtion in Arctic. V. 1: Reserch drifting sttion "North Pole", SP: Nuk, 2005, P s/lhidro 15. Ivnov V.V., Alekseev V.A., Alekseev T.A., Koldunov N.V., Repin I.A., Smirnov A.V. Does Arctic ice cover ecome sesonl?// Erth Res. from Spce, 4, 2013, pp Johnnessen O.M., Bengtsson L., Miles M.W., Kuzmin S.I., Semenov V.A., Alekseev G.V., Ngurnyi A.P., Zkhrov V.F., Boylev L.P., Pettersson L.H., Hsselmnn K., Cttle H.P., Arctic climte chnge: oserved nd modelled temperture nd se ice vriility // Tellus, 56A, 2004, pp Kwok R., Rothrock D.A. Decline in Arctic se ice thickness from sumrine nd ICESt records: // Geophys. Res. Lett., 36, L15501, 2009, doi: /2009gl Løyning T., Dick C., Goodwin H., Pvlov O., Vinje T., Kjærnli G., Villinger T. ACSYS historicl ice chrt rchive ( ). Interntionl ACSYS/CliC Project Office Mhoney A.R., Brry R.G., Smolynitsky V., Fetterer F. Oserved se ice extent in the Russin Arctic, // J. Geophys. Res., 113(C11005), 2008, doi: /2008jc Overlnd J.E., Wng M. When will the summer Arctic e nerly se ice free? // Geophys. Res. Lett., 40, 2013, pp , doi: /grl Ryner N.A., Prker D.E., Horton E.B., Follnd C.K., Alexnder L.V., Rowell D.P., Kent E.C., Kpln A. Glol nlyses of se surfce temperture, se ice, nd night mrine ir temperture since the lte nineteenth century // J. Geophys. Res., 108(D14), 4407, 2003, doi: /2002jd Semenov V.A., Ltif M. The erly twentieth century wrming nd winter Arctic se ice // The Cryosphere, 6, 2012, pp doi: /tc Smolynitskiy V.M. Sptio-temporl vriility of ice cover on the sis of the "Glol Bnk of digitl dt out se ice" // strct of Ph.D. thesis, SP: AARI, 2003, P Stroeve J.C., Hollnd M.M., Meier W., Scmos T., Serreze M. Arctic se ice decline: Fster thn forecst // Geophys. Res. Lett, 34, L09501, 2007, doi: /2007gl Stroeve J.C., Mrkus T., Boisvert L., Miller J., Brrett A. Chnges in Arctic melt seson nd implictions for se ice loss // Geophys. Res. Lett, 41, 2014, doi: /2013gl Stroeve J.C., Serreze M.C., Hollnd M.M., Ky J.E., Mlnik J., Brrett A.P. The Arctic s rpidly shrinking se icecover: reserch synthesis // Clim. Chnge, 2011, doi: /s Vinje T. Anomlies nd trends of se ice extent nd tmospheric circultion in the Nordic Ses during the period // Journl of Climte, V.14, No.3, 2001, pp Vise V.Yu. Bses of long-term ice forecsts for the Arctic Ses. M. Glvsevmorput P Vise V.Yu. The reson of the Arctic wrming // Sovetsky Arktik, 1, 1937, pp Zkhrov V.F. Arctic cooling nd Arctic Ses ice cover. Proceedings of the AARI P. 96 ISBN:

7 31. Zkhrov V.F. Interdecdl chnges of Arctic se ice distriution in twentieth century // formtion nd dynmics of the modern Arctic climte. edited y Alekseev G.V. SP: Gidrometeoizdt, 2004, pp Zkhrov.V.F. Ice of the Arctic nd current nturl processes. L. Gidrometeoizdt P Zkhrov.V.F. The World Ocen nd glcil epochs of the Pleistocene. L. Gidrometeoizdt, 1978, P. 64 ISBN: