View source for Regional patterns of holocene climate change in Antarctica

:''This page is part of the topic [[The Holocene]]''

In this section we provide a spatial synthesis of records of climate and environmental changes in East Antarctica (EA), the Antarctic Peninsula (AP), and the Ross Sea region (RS). West Antarctica, which is currently understudied, is also briefly described. We build on previous reviews by Ing&oacute;lfsson et al. (1998<ref name="Ing&oacute;lfsson et al, 1998">Ing&oacute;lfsson, &Oacute;., Hjort, C., Berkman, P.A., Bj&ouml;rck, S., Colhoun, E.A., Goodwin, I.D., Hall, B.L., Hirakawa, K., Melles, M., M&ouml;ller, P. and Prentice, M.L. 1998. Antarctic glacial history since the last glacial maximum: an overview of the record on land, ''Antarctic Science'', '''10''', 326-344.</ref>, 2003<ref name="Ing&oacute;lfsson et al, 2003">Ing&oacute;lfsson, &Oacute;., Hjort, C. and Humlum, O. 2003. Glacial and Climate History of the Antarctic Peninsula since the Last Glacial Maximum, Arctic, ''Antarctic and Alpine Research'', '''35''', 175-186.</ref>), Ing&oacute;lfsson and Hjort (2002<ref name="Ing&oacute;lfsson and Hjort, 2002">Ing&oacute;lfsson, &Oacute;. and Hjort, C. 2002. Glacial history of the Antarctic Peninsula since the Last Glacial Maximum-a synthesis, ''Polar Biology'', '''21''', 227-234.</ref>), Ing&oacute;lfsson (2004<ref name="Ing&oacute;lfsson, 2004">Ing&oacute;lfsson, &Oacute;. 2004. Quaternary glacial and climate history of Antarctica. In: Ehlers J, Gibbard PL (eds), Quaternary Glaciations - Extent and Chronology, Part III, Elsevier, 3-43.</ref>), Jones et al. (2000<ref name="Jones et al, 2000">Jones, V.J., Hodgson, D.A. and Chepstow-Lusty, A. 2000. Palaeolimnological evidence for marked Holocene environmental changes on Signy Island, Antarctica, ''The Holocene'', '''10''', 43-60.</ref>) and Hodgson et al. (2004a<ref name="Hodgson et al, 2004a">Hodgson, D.A., Doran, P.T., Roberts, D. and McMinn, A. 2004a. Paleolimnological studies from the Antarctic and subantarctic islands. In: Pienitz R, Douglas MSV, Smol JP (eds) Developments in Palaoenvironmental Research. Long-term Environmental Change in Arctic and Antarctic Lakes, 8, Springer, Dordrecht, 419-474.</ref>) and focus on four main periods, namely: (1) the deglaciation history of currently ice-free regions and the Pleistocene-Holocene transition; (2) the period after the early Holocene, (3) the Mid Holocene warm period or Hypsithermal (MHH), and (4) the past 2,000 years with a focus on Neoglacial cooling, the presence of warm periods, the possibility of a Little Ice Age (LIA) like event, and the recent rapid climate changes documented in instrumental and observational records. It should be noted that these climate periods are not always synchronous in different regions of Antarctica which might in part be due to different degrees of chronological control, or to forcing mechanisms operating at different intensities between regions. At present, with the exception of the Antarctic Peninsula (Bentley et al., 2009<ref name="Bentley et al, 2009">Bentley, M.J., Hodgson, D.A., Smith, J.A., &Oacute; Cofaigh, C., Domack, E.W., Larter, R.D., Roberts, S.J., Brachfeld, S., Leventer, A., Hjort, C., Hillenbrand, C-D. and Evans, J. 2009. Mechanisms of Holocene palaeoenvironmental change in the Antarctic Peninsula region, ''The Holocene'', '''19''', 51-69.</ref>), the role of various forcing mechanisms in regional climate change is poorly described.

In order to allow comparison between the different records in studies where <sup>14</sup>C dates were not calibrated we list the original <sup>14</sup>C dates (<sup>14</sup>C ka BP), together with the upper and lower limits (at 2-std deviations) of the data (cal. ka BP) generated by the radiocarbon calibration method CALIB 5.0.2 (http://calib.qub.ac.uk/calib/). Radiocarbon dates of marine samples were corrected for the reservoir effect by subtracting 1,300 yrs following the Antarctic standard prior to calibration (i.e. the offset from the global marine reservoir was set at 900 years when using the marine calibration curve; Hughen et al. (2004<ref name="Hughen et al, 2004">Hughen, K.A., Baillie, M.G.L., Bard, E., Beck, J.W., Bertrand, C.J.H., Blackwell, P.G., Buck, C.E., Burr, G.S., Cutler, K.B., Damon, P.E., Edwards, R.L., Fairbanks, R.G., Friedrich, M., Guilderson, T.P., Kromer, B., McCormac, G., Manning, S., Ramsey, C.B., Reimer, P.J., Reimer, R.W., Remmele, S., Southon, J.R., Stuiver, M., Talamo, S., Taylor, F.W., Van Der Plicht, J. and Ce, W. 2004. Marine Radiocarbon Age Calibration 0-26 Cal Kyr Bp, ''Radiocarbon'', '''46''',1059-1108.</ref>)). For lacustrine <sup>14</sup>C ages younger than 11 ka cal yr BP the Southern Hemisphere atmospheric calibration curve was used (McCormac et al., 2004<ref name="McCormac et al, 2004">McCormac, F., Hogg, A., Blackwell, P., Buck, C., Higham, T. and Reimer, P. 2004. Shcal04 Southern Hemisphere Calibration 0-11.0 Cal Kyr Bp, ''Radiocarbon'', '''46''', 1087-1092.</ref>); in all other cases the Northern Hemisphere atmospheric calibration curve (Reimer et al., 2004<ref name="Reimer et al, 2004">Reimer, P.J., Baillie, M.G.L., Bard, E., Bayliss, A., Beck, J.W., Bertrand, C.J.H., Blackwell, P.G., Buck, C.E., Burr, G.S., Cutler, K.B., Damon, P.E., Edwards, R.L., Fairbanks, R.G., Friedrich, M., Guilderson, T.P., Hogg, A.G., Hughen, K.A., Kromer, B., McCormac G., Manning S., Ramsey C.B., Reimer R.W., Remmele, S., Southon, J.R., Stuiver, M., Talamo, S., Taylor, F.W., Van Der Plicht, J. and Weyhenmeyer, C.E. 2004. Intcal04 Terrestrial Radiocarbon Age Calibration, 0-26 Cal Kyr Bp, ''Radiocarbon'', '''46''', 1029-1058.</ref>) was applied. The dates of deglaciation of the current ice-free regions are largely derived from <sup>14</sup>C dating of fossils in raised beaches, organic material and fossils in lake sediments, peat deposits and bird colonies; they are thus minimum ages since there is an unknown lag time between deglaciation and colonization of the land by biota (e.g. Gore, 1997<ref name="Gore, 1997">Gore, D.B. 1997. Blanketing snow and ice; constraints on radiocarbon dating deglaciation in East Antarctic oases, ''Antarctic Science'', '''9''', 336-346.</ref>; Ing&oacute;lfsson et al., 2003<ref name="Ing&oacute;lfsson et al, 2003">Ing&oacute;lfsson, &Oacute;., Hjort, C. and Humlum, O. 2003. Glacial and Climate History of the Antarctic Peninsula since the Last Glacial Maximum, Arctic, ''Antarctic and Alpine Research'', '''35''', 175-186.</ref>).

Summary: In general, geological evidence shows that deglaciation of the currently ice-free regions was completed earlier in EA compared with the AP, but all periods experienced a near-synchronous early Holocene climate optimum (11.5-9 ka BP). Marine and terrestrial climate anomalies are apparently out of phase after the early Holocene warm period, and show complex regional patterns but an overall trend of cooling. A warm mid Holocene Hypsithermal is present in many ice, lake and coastal marine records from all three geographic regions, although there are some differences in the exact timing. In EA and the AP (excluding the northernmost islands) the Hypsithermal occurs somewhere between c. 4 and 2 ka BP, whereas at Signy Island it spanned 3.6-3.4 &ndash; 0.9 ka BP. Despite this there are a number of marine records that show a marine-inferred climate optimum between about 7-3 ka BP and ice cores in the RS sector that show an optimum around 7-5 ka BP, and the EPICA Dome C ice core, and some others, show a weak optimum between 7.5 and 3 ka BP. The occurrence of a later Holocene climate optimum in the RS is in phase with a marked cooling observed in ice cores from coastal and inland locations (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>; Masson-Delmotte et al., 2004<ref name="Masson-Delmotte et al, 2004">Masson-Delmotte, V., Stenni, B. and Jouzel, J. 2004. Common millennial-scale variability of Antarctic and Southern Ocean temperatures during the past 5000 years reconstructed from the EPICA Dome C ice core, ''The Holocene'', '''14''', 145-151.</ref>). These differences in the timing of warm events in different records and regions points to the interplay of a number of mechanisms that we have yet to identify. Thus there is an urgent need for well-dated, high resolution climate records in coastal Antarctica and particularly in the Dronning Maud Land region and specific regions of the AP to fully understand these regional climate anomalies and to determine the significance of the heterogeneous temperature trends being measured in Antarctica today. There is no geological evidence in Antarctica for an equivalent to the Northern Hemisphere Medieval Warm Period, there is only weak circumstantial evidence in a few places for a cool event crudely equivalent in time to the Northern Hemisphere&rsquo;s Little Ice Age but not in phase (Goosse et al., 2004<ref name="Goosse et al, 2004">Goosse, H., Masson-Delmotte, V., Renssen, H., Delmotte, M., Fichefet, T., Morgan, V., Van Ommen, T., Khim, B.K. and Stenni, B. 2004. A late medieval warm period in the Southern Ocean as a delayed response to external forcing? Geophysical Research Letters, 31, L06203, doi:06210.01029/02003GL019140.</ref>), and it is likely beyond the current signal to noise ratio of ice cores to detect the c. 0.5&deg;C change believed to have occurred at that time.
==Pages in this topic==
#[[Holocene climate change in East Antarctica (EA)]]
#[[Holocene climate change in the Antarctic Peninsula (AP)]]
#[[Holocene climate change in the Ross Sea region (RS)]]
==References==
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[[Category:The pre-instrumental period]]
[[Category:The Holocene]]