11:00 〜 13:00
[U05-P06] Regional and global forcing of Holocene Totten Glacier retreat from deep-sea sediments perspective
キーワード：海面上昇、東南極氷床、トッテン氷河、ベリリウム同位体、粒度、熱塩循環
Sea level rise is one of the greatest challenges we face in the 21st century. How high and how soon the water rises has a lot to do with what happens in Antarctica. The East Antarctic Ice Sheet is the biggest source of potential sea level rise on Earth. If the entire ice sheet melts all at once, the global sea level will rise by about 53 m (1). Although this will not happen overnight or any time soon, a small change in the ice sheet can have large impacts all over the world. Marine-based sectors with ice grounded below sea level, such as the Totten Glacier in East Antarctica, are especially vulnerable to oceanic warming and hence sensitive to past, present, and future climate warming. An accurate reconstruction of the Totten Glacier’s past is needed to better understand the glacier’s response to present and future climate changes.
The physical, elemental, and isotopic composition of marine sediments give us hints of how the ice has reacted to past warming. We used beryllium isotope and grain size analysis to evaluate the Totten Glacier dynamics and interaction with the Southern Ocean since the Last Glacial Maximum. Our beryllium isotopes and grain size records reveal that the initial deglaciation of the Totten Glacier sector of the East Antarctic Ice Sheet started from around 17 ka, followed by rapid deglaciation from around 8.5 ka, likely due to the intrusion of warm ocean currents to the grounding line of the Totten Glacier.
It is possible that the Totten Glacier region of the East Antarctic Ice Sheet is in sync with changes in global ice volume. The synchronicity between the global ice volume and the Totten Glacier may be evidence for a teleconnection between global and Antarctic climates. Low-latitude signals such as El Niño-Southern Oscillation may have influenced Southern Hemisphere trade winds (2) via the Southern Annular Mode (3). This may have in turn influenced cyclonic activities along the Antarctic coast (4), creating upwelling that allows the intrusion of warm Circumpolar Deep Water under the ice shelf and leading to basal melting.
(1) Fretwell, P., Pritchard, H.D., Vaughan, D.G., Bamber, J.L., Barrand, N.E., Bell, R., Bianchi, C., Bingham, R.G., Blankenship, D.D., Casassa, G., Catania, G., Callens, D., Conway, H., Cook, A.J., Corr, H.F.J., Damaske, D., Damm, V., Ferraccioli, F., Forsberg, R., Fujita, S., Gim, Y., Gogineni, P., Griggs, J.A., Hindmarsh, R.C.A., Holmlund, P., Holt, J.W., Jacobel, R.W., Jenkins, A., Jokat,W., Jordan, T., King, E.C., Kohler, J., Krabill,W., Riger-Kusk, M., Langley, K.A., Leitchenkov, G., Leuschen, C., Luyendyk, B.P., Matsuoka, K., Mouginot, J., Nitsche, F.O., Nogi, Y., Nost, O.A., Popov, S.V., Rignot, E., Rippin, D.M., Rivera, A., Roberts, J., Ross, N., Siegert, M.J., Smith, A.M., Steinhage, D., Studinger, M., Sun, B., Tinto, B.K., Welch, B.C., Wilson, D., Young, D.A., Xiangbin, C., Zirizzotti, A., 2013. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 7, 375e393.
(2) Pike, J., Swann, G.E.A., Leng, M.J., Snelling, A.M., 2013. Glacial discharge along the west Antarctic Peninsula during the Holocene. Nat. Geosci. 6, 199e202.
(3) Abram, N. J., Mulvaney, R., Vimeux, F., Phipps, S. J., Turner, J., & England, M. H. (2014). Evolution of the Southern Annular Mode during the past millennium. Nature Climate Change, 4(7), 564-569.
(4) Yokoyama, Y., Hirabayashi, S., Goto, K., Okuno, J. I., Sproson, A. D., Haraguchi, T., ... & Miyairi, Y. (2019). Holocene Indian Ocean sea level, Antarctic melting history and past Tsunami deposits inferred using sea level reconstructions from the Sri Lankan, Southeastern Indian and Maldivian coasts. Quaternary Science Reviews, 206, 150-161.
The physical, elemental, and isotopic composition of marine sediments give us hints of how the ice has reacted to past warming. We used beryllium isotope and grain size analysis to evaluate the Totten Glacier dynamics and interaction with the Southern Ocean since the Last Glacial Maximum. Our beryllium isotopes and grain size records reveal that the initial deglaciation of the Totten Glacier sector of the East Antarctic Ice Sheet started from around 17 ka, followed by rapid deglaciation from around 8.5 ka, likely due to the intrusion of warm ocean currents to the grounding line of the Totten Glacier.
It is possible that the Totten Glacier region of the East Antarctic Ice Sheet is in sync with changes in global ice volume. The synchronicity between the global ice volume and the Totten Glacier may be evidence for a teleconnection between global and Antarctic climates. Low-latitude signals such as El Niño-Southern Oscillation may have influenced Southern Hemisphere trade winds (2) via the Southern Annular Mode (3). This may have in turn influenced cyclonic activities along the Antarctic coast (4), creating upwelling that allows the intrusion of warm Circumpolar Deep Water under the ice shelf and leading to basal melting.
(1) Fretwell, P., Pritchard, H.D., Vaughan, D.G., Bamber, J.L., Barrand, N.E., Bell, R., Bianchi, C., Bingham, R.G., Blankenship, D.D., Casassa, G., Catania, G., Callens, D., Conway, H., Cook, A.J., Corr, H.F.J., Damaske, D., Damm, V., Ferraccioli, F., Forsberg, R., Fujita, S., Gim, Y., Gogineni, P., Griggs, J.A., Hindmarsh, R.C.A., Holmlund, P., Holt, J.W., Jacobel, R.W., Jenkins, A., Jokat,W., Jordan, T., King, E.C., Kohler, J., Krabill,W., Riger-Kusk, M., Langley, K.A., Leitchenkov, G., Leuschen, C., Luyendyk, B.P., Matsuoka, K., Mouginot, J., Nitsche, F.O., Nogi, Y., Nost, O.A., Popov, S.V., Rignot, E., Rippin, D.M., Rivera, A., Roberts, J., Ross, N., Siegert, M.J., Smith, A.M., Steinhage, D., Studinger, M., Sun, B., Tinto, B.K., Welch, B.C., Wilson, D., Young, D.A., Xiangbin, C., Zirizzotti, A., 2013. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 7, 375e393.
(2) Pike, J., Swann, G.E.A., Leng, M.J., Snelling, A.M., 2013. Glacial discharge along the west Antarctic Peninsula during the Holocene. Nat. Geosci. 6, 199e202.
(3) Abram, N. J., Mulvaney, R., Vimeux, F., Phipps, S. J., Turner, J., & England, M. H. (2014). Evolution of the Southern Annular Mode during the past millennium. Nature Climate Change, 4(7), 564-569.
(4) Yokoyama, Y., Hirabayashi, S., Goto, K., Okuno, J. I., Sproson, A. D., Haraguchi, T., ... & Miyairi, Y. (2019). Holocene Indian Ocean sea level, Antarctic melting history and past Tsunami deposits inferred using sea level reconstructions from the Sri Lankan, Southeastern Indian and Maldivian coasts. Quaternary Science Reviews, 206, 150-161.