View source for Holocene climate change in the Ross Sea region (RS)

:''This page is part of the topic [[Regional patterns of holocene climate change in Antarctica]]''

==Deglaciation history the Pleistocene-Holocene transition==

[[File:Figure 3.28 - Selected Holocene environmental changes - Ross Sea.png|thumb|'''3.28''' Selected Holocene environmental changes &ndash; Ross Sea]]
A grounded ice sheet fed from the Ross Embayment filled McMurdo Sound at the LGM and remained at its LGM position until c. 12.7 <sup>14</sup>C ka BP (c. 14.7-15.2 ka BP). The following ice recession was slow until c. 10.8 <sup>14</sup>C ka BP (c. 12.7-12.9 ka BP) (Denton and Marchant, 2000<ref name="Denton and Marchant, 2000">Denton, G.H. and Marchant, D.R. 2000. The geologic basis for a reconstruction of a grounded ice sheet in McMurdo Sound, Antarctica, at the last glacial maximum, ''Geografiska Annaler Series a-Physical Geography'', '''82A''', 167-211.</ref>; Hall and Denton, 2000<ref name="Hall and Denton, 2000">Hall, B.L. and Denton, G.H. 2000. Extent and Chronology of the Ross Sea Ice Sheet and the Wilson Piedmont Glacier Along the Scott Coast at and Since the Last Glacial Maximum, ''Geografiska Annaler Series a-Physical Geography'', '''82A''', 337-363.</ref>) ([[:File:Figure 3.28 - Selected Holocene environmental changes - Ross Sea.png|Figure 3.28]]). The Piedmont Glacier was probably also at its LGM position at c. 10.7 <sup>14</sup>C ka BP (c. 12.6-12.8 ka BP) (Hall and Denton, 2000<ref name="Hall and Denton, 2000">Hall, B.L. and Denton, G.H. 2000. Extent and Chronology of the Ross Sea Ice Sheet and the Wilson Piedmont Glacier Along the Scott Coast at and Since the Last Glacial Maximum, ''Geografiska Annaler Series a-Physical Geography'', '''82A''', 337-363.</ref>). The grounded ice sheet blocked several valleys in the McMurdo Dry Valleys and fed large proglacial lakes such as Lake Washburn and Lake Wright, which had water over 500 m deep in some valleys (Hall and Denton, 1995<ref name="Hall and Denton, 1995">Hall, B.L. and Denton, G.H. 1995. Late Quaternary lake levels in the Dry Valleys, Antarctica, ''Antarctic Journal of the United States'', '''30''', 52-53.</ref>) and existed until the early Holocene (Hall et al., 2000<ref name="Hall et al, 2000">Hall, B.L., Denton, G.H. and Hendy, C.H. 2000. Evidence from Taylor Valley for a Grounded Ice Sheet in the Ross Sea, Antarctica, ''Geografiska Annaler'', '''82A''', 275-303.</ref>; Hendy, 2000<ref name="Hendy, 2000">Hendy, C.H. 2000. Late Quaternary lakes in the McMurdo Sound region of Antarctica, Geografiska Annaler, 82 A, 411-432.</ref>; Hall et al., 2001<ref name="Hall et al, 2001">Hall, B.L., Denton, G.H. and Overturf, B. 2001. Glacial Lake Wright, a high-level Antarctic lake during the LGM and early Holocene, ''Antarctic Science'', '''13''', 53-60.</ref>). The large amount of water in these lakes was probably derived from melting glaciers as a result of dry and cold conditions, which led to decreased snowfall and lower albedo values (Hall and Denton, 2002<ref name="Hall and Denton, 2002">Hall, B.L. and Denton, G.H. 2002. Holocene history of the Wilson Piedmont Glacier along the southern Scott Coast, Antarctica, ''The Holocene'', '''12''', 619-627.</ref>). Between c. 14 ka and 8 ka BP these large proglacial lakes started to evaporate (Hendy, 2000<ref name="Hendy, 2000">Hendy, C.H. 2000. Late Quaternary lakes in the McMurdo Sound region of Antarctica, Geografiska Annaler, 82 A, 411-432.</ref>); the evaporation of Lake Washburn started during the LGM. Lake level lowering was discontinuous, with a series of high and low stands (Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>). Significant changes evident in the geochemistry of a sediment core from Lake Fryxell between c. 13.5 and 11 ka BP suggest a further desiccation event at the Pleistocene-Holocene transition (Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>).

==After the early Holocene==

The last remnants of grounded ice in Taylor Valley post-date c. 8.4 <sup>14</sup>C ka BP (c. 9-9.4 ka BP), and penguins did not recolonize the RS region until c. 8 ka BP, after an absence of c. 19 Ka (Hall et al., 2006<ref name="Hall et al, 2006">Hall, B.L., Hoelzel, A.R., Baroni, C., Denton, G.H., Le Boeuf, B.J., Overturf, B. and Topf, A.L. 2006. Holocene Elephant Seal Distribution Implies Warmer-Than-Present Climate in the Ross Sea, Proceedings of the National Academy of Sciences of the United States of America, 103, 10213-10217.</ref>; Emslie et al., 2007<ref name="Emslie et al, 2007">Emslie, S.D., Coats, L. and Licht, K. 2007. A 45,000 Yr Record of Adelie Penguins and Climate Change in the Ross Sea, Antarctica, ''Geology'', '''35''', 61-64.</ref>). The period from c. 8 ka BP shows some discrepancies. Evidence from relict deltas for an increase in the moisture supply at c. 6 <sup>14</sup>C ka BP (c. 6.8 ka BP, Hall et al., 2000<ref name="Hall et al, 2000">Hall, B.L., Denton, G.H. and Hendy, C.H. 2000. Evidence from Taylor Valley for a Grounded Ice Sheet in the Ross Sea, Antarctica, ''Geografiska Annaler'', '''82A''', 275-303.</ref>)) contrasts with evidence for increased salinity between c. 9 and 4 ka BP in a sediment core from Lake Fryxell (Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>). This discrepancy could be explained by dating uncertainties or the relict deltas being from smaller local lakes (Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>).

[[File:Figure 3.17 - Sea ice distribution at the Southern Ocean EPILOG-LGM time slice.png|thumb|'''3.17''' Sea ice distribution at the Southern Ocean EPILOG-LGM (E-LGM) time slice. E-LGM-winter sea ice (E-LGM-WSI) indicates maximum extent of winter sea ice (September concentration &gt;15%). Modern winter sea ice (M-WSI) shows extent of &gt;15% September sea ice concentration according to Comiso et al. (2003<ref name="Comiso et al, 2003">Comiso, J.C., Cavalieri, D.J. and Markus, T. 2003. Sea ice concentration, ice temperature, and snow depth using AMSR-E data, ''IEEE Trans Geosci Remote Sensing'', '''41''', 243, doi:210.1109/TGRS.2002.808317.</ref>). Values indicate estimated winter (September) sea ice concentration in percent derived with Modern Analog Techniques and Generalized Additive Models. Signature legend: (1) concomitant occurrence of cold-water indicator diatom ''F. obliquecostata'' (&gt;1% of diatom assemblage) and summer sea ice (February concentration &gt;0%) interpreted to represent sporadic occurrence of ELGM summer sea ice; (2) presence of WSI (September concentration &gt;15%, diatom WSI indicators &gt;1%); (3) no WSI (September concentration &lt;15%, diatom WSI indicators &lt;1%) (Gersonde et al., 2005<ref name="Gersonde et al, 2005">Gersonde, R., Crosta, X., Abelmann, A. and Armand, L. 2005. Sea-surface temperature and sea ice distribution of the Southern Ocean at the EPILOG Last Glacial Maximum-a circum-Antarctic view based on siliceous microfossil records, ''Quaternary Science Reviews'', '''24''', 869-896.</ref>)]]
The presence of hairs from Southern Elephant Seals along with the remains of Ad&eacute;lie Penguins between c. 6 and 4 <sup>14</sup>C ka BP, indicates less sea ice than today, but sufficient pack ice for penguins to forage during spring (Emslie et al., 2007<ref name="Emslie et al, 2007">Emslie, S.D., Coats, L. and Licht, K. 2007. A 45,000 Yr Record of Adelie Penguins and Climate Change in the Ross Sea, Antarctica, ''Geology'', '''35''', 61-64.</ref>). The final retreat of the Ross Ice Sheet and deglaciation is estimated to have occurred around that time; c. 5.4 <sup>14</sup>C ka BP (c. 6.3 - 5.9 ka BP, Hall and Denton, 2000<ref name="Hall and Denton, 2000">Hall, B.L. and Denton, G.H. 2000. Extent and Chronology of the Ross Sea Ice Sheet and the Wilson Piedmont Glacier Along the Scott Coast at and Since the Last Glacial Maximum, ''Geografiska Annaler Series a-Physical Geography'', '''82A''', 337-363.</ref>), coincident with the start of the recession of parts of the Wilson Piedmont Glacier at c. 5.5 <sup>14</sup>C ka BP (c. 6.4-6.27 ka BP) that lasted until at least c. 4.4-3.1 <sup>14</sup>C ka BP (c. 5.2-4.8 - 3.5-3.3 ka BP, Hall and Denton, 2000<ref name="Hall and Denton, 2000">Hall, B.L. and Denton, G.H. 2000. Extent and Chronology of the Ross Sea Ice Sheet and the Wilson Piedmont Glacier Along the Scott Coast at and Since the Last Glacial Maximum, ''Geografiska Annaler Series a-Physical Geography'', '''82A''', 337-363.</ref>)). This corresponds with a secondary climate optimum detected in the ice cores of the RS sector, between 7 and 5 ka BP (Masson et al., 2000<ref name="Masson et al, 2000">Masson, V., Vimeux, F., Jouzel, J., Morgan, V., Delmotte, M., Ciais, P., Hammer, C., Johnsen, S., Lipenkov, V.Y., Mosley-Thompson, E., Petit, J.R., Steig, E.J., Stievenard, M. and Vaikmae, R. 2000. Holocene climate variability in Antarctica based on 11 ice-core isotope records, ''Quaternary Research'', '''54''', 348-358.</ref>), and at Siple Dome c 5.2 ka ([[:File:Figure 3.17 - Sea ice distribution at the Southern Ocean EPILOG-LGM time slice.png|Figure 3.17]]).

==The Mid Holocene==

In Lake Fryxell well-developed microbial mats occurred from c. 4 ka BP onwards, which indicates similar environmental conditions and water depths to those found today (Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>). Between c. 4 and 2.3 <sup>14</sup>C ka BP (c. 4.8-4.4 and 2.6-2.3 ka BP) elephant seals are completely absent from the region, whereas the Ad&eacute;lie Penguin population increased between c. 4 and 3 ka BP (Baroni and Orombelli, 1994<ref name="Baroni and Orombelli, 1994">Baroni, C. and Orombelli, G. 1994. Abandoned pengiun rookeries as Holocene paleoclimatic indicators in Antarctica, ''Geology'', '''22''', 23-26.</ref>; Emslie and Woehler, 2005<ref name="Emslie and Woehler, 2005">Emslie, S.D., Woehler, E.J. 2005. A 9000-year record of Ad&eacute;lie penguin occupation and diet in the Windmill Islands, East Antarctica, ''Antarctic Science'', '''17''', 57-66.</ref>). These data suggest that there was sufficient pack ice, but less than today, implying that conditions were relatively warm (Hall et al., 2006<ref name="Hall et al, 2006">Hall, B.L., Hoelzel, A.R., Baroni, C., Denton, G.H., Le Boeuf, B.J., Overturf, B. and Topf, A.L. 2006. Holocene Elephant Seal Distribution Implies Warmer-Than-Present Climate in the Ross Sea, Proceedings of the National Academy of Sciences of the United States of America, 103, 10213-10217.</ref>). This so-called &lsquo;penguin optimum&rsquo; was followed by a period of high lake levels between c. 3 and 2 <sup>14</sup>C ka BP (c. 3.3-2.9 and 2-1.7 ka BP) in water bodies fed by meltwater from alpine glaciers (e.g. Lake Vanda, Hendy, 2000<ref name="Hendy, 2000">Hendy, C.H. 2000. Late Quaternary lakes in the McMurdo Sound region of Antarctica, Geografiska Annaler, 82 A, 411-432.</ref>). The Wilson Piedmont Glacier was less extensive than at present from c. 3.1 <sup>14</sup>C ka BP onwards until c. 0.9 <sup>14</sup>C ka BP (c. 3.5-3.2 and 1.1-0.8 ka BP; (Hall and Denton, 2000<ref name="Hall and Denton, 2000">Hall, B.L. and Denton, G.H. 2000. Extent and Chronology of the Ross Sea Ice Sheet and the Wilson Piedmont Glacier Along the Scott Coast at and Since the Last Glacial Maximum, ''Geografiska Annaler Series a-Physical Geography'', '''82A''', 337-363.</ref>)).

==The past 2,000 years &ndash; Late Holocene warm period and recent rapid climate change==

In contrast to the AP, the warmest conditions in the RS region during the Holocene did not occur during the mid Holocene but rather during the late Holocene, as evidenced by the presence of elephant seal hairs. The warmest period of the past 6,000 years occurred between c. 2.3 and 1.1 ka <sup>14</sup>C BP (c. 2.6-2.3 and 1.2-0.9 ka BP) accompanied by the greatest decline in sea ice, as evidenced from an expansion of the elephant seal colonies (Hall et al., 2006<ref name="Hall et al, 2006">Hall, B.L., Hoelzel, A.R., Baroni, C., Denton, G.H., Le Boeuf, B.J., Overturf, B. and Topf, A.L. 2006. Holocene Elephant Seal Distribution Implies Warmer-Than-Present Climate in the Ross Sea, Proceedings of the National Academy of Sciences of the United States of America, 103, 10213-10217.</ref>), and substantial abandonment of penguin sites (Emslie et al., 2007<ref name="Emslie et al, 2007">Emslie, S.D., Coats, L. and Licht, K. 2007. A 45,000 Yr Record of Adelie Penguins and Climate Change in the Ross Sea, Antarctica, ''Geology'', '''35''', 61-64.</ref>). This period was followed by a period of enhanced evaporation, which lasted until 1 ka BP, when Lakes Fryxell, Vanda and Bonney evaporated to ice-free hypersaline ponds by c. 1.2-1 ka BP (Lyons et al., 1998<ref name="Lyons et al, 1998">Lyons, W.B., Tyler, S.W., Wharton, R.A., McKnight, D.M. and Vaughan, B.H. 1998. A late Holocene desiccation of Lake Hoare and Lake Fryxell, McMurdo Dry Valleys, Antarctica, ''Antarctic Science'', '''10''', 247-256.</ref>; Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>), and when Lake Wilson, a perennially ice-capped, deep (&gt;100 m) lake further South (80&deg;S) in southern Victoria Land, similarly evaporated to a brine lake (Webster et al., 1996<ref name="Webster et al, 1996">Webster, J., Hawes, I., Downes, M., Timpeley, M. and Howard-Williams, C. 1996. Evidence for regional climate change in the recent evolution of a high latitude pro-glacial lake, ''Antarctic Science'', '''8''', 49-59.</ref>). After 1 ka BP, warmer and wetter conditions led to increasing water levels and primary production in the lakes (Lyons et al., 1998<ref name="Lyons et al, 1998">Lyons, W.B., Tyler, S.W., Wharton, R.A., McKnight, D.M. and Vaughan, B.H. 1998. A late Holocene desiccation of Lake Hoare and Lake Fryxell, McMurdo Dry Valleys, Antarctica, ''Antarctic Science'', '''10''', 247-256.</ref>; Wagner et al., 2006<ref name="Wagner et al, 2006">Wagner, B., Melles, M., Doran, P.T., Kenig, F., Forman, S.L., Pierau, R. and Allan, P. 2006. Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, southern Victoria Land, Antarctica, Palaeography, Palaeoclimatology, ''Palaeoecology'', '''241''', 320-337.</ref>). This has been attributed to higher summer temperatures or to an increase in the number of clear, calm and snowless midsummer days (Hendy, 2000<ref name="Hendy, 2000">Hendy, C.H. 2000. Late Quaternary lakes in the McMurdo Sound region of Antarctica, Geografiska Annaler, 82 A, 411-432.</ref>). During the last few centuries (&lt; c. 0.2 <sup>14</sup>C ka BP, c. 0.4-0.1 ka BP) the Wilson Piedmont Glacier was more extensive than today in some areas until AD 1956 (Hall and Denton, 2002<ref name="Hall and Denton, 2002">Hall, B.L. and Denton, G.H. 2002. Holocene history of the Wilson Piedmont Glacier along the southern Scott Coast, Antarctica, ''The Holocene'', '''12''', 619-627.</ref>). There is no sign in the McMurdo Dry Valleys of the pattern of glacier advances typical of the Northern Hemisphere Little Ice Age (Hall and Denton, 2002<ref name="Hall and Denton, 2002">Hall, B.L. and Denton, G.H. 2002. Holocene history of the Wilson Piedmont Glacier along the southern Scott Coast, Antarctica, ''The Holocene'', '''12''', 619-627.</ref>).

Studies in the framework of the US Long Term Ecological Research program have revealed a rapid ecosystem response to local climate cooling in the McMurdo Dry Valleys during recent decades, as evidenced by a decline in lake primary production and declining numbers of soil invertebrates (Doran et al., 2002<ref name="Doran et al, 2002">Doran, P.T., Priscu, J.C., Lyons, W.B., Walsh, J.E., Fountain, A.G., McKnight, D.M., Moorhead, D.L., Virginia, R.A., Wall, D.H., Clow, G.D., Fritsen, C.H., McKay, C.P. and Parsons, A.N. 2002. Antarctic climate cooling and terrestrial ecosystem response, ''Nature'', '''415''', 517-520.</ref>).
==References==
<references />
[[Category:The pre-instrumental period]]
[[Category:The Holocene]]