ProfessorMartinSiegert

Research description: MEASUREMENT AND MODELLING OF THE ANTARCTIC ICE SHEET

The aim of my research is to understand the sensitivity of the Antarctic ice sheet to global warming, and to predict its impact on future sea-level change. To do this, I use numerical ice-sheet modelling to quantify ice flow processes, allowing predictive assessments of change and reconstructions of past events. Ice-sheet modelling requires boundary conditions in the form of basic ice-sheet measurements (such as ice surface and bed elevations), and information that can be used to assess the reliability of output. To these ends geophysical measurements of the ice sheet are essential, and form a substantial component of my research activity. I have undertaken measurement and modelling investigations in both East and West Antarctica, focusing on potential vulnerable margins where existing knowledge is poor (or non-existent). I also lead research on the exploration of the subglacial system, to comprehend ice-sheet and biogeochemical processes and extract records of past ice-sheet changes.

Published research achievements in the past year

1. A new Antarctic bed topography compilation, which utilises geophysical data collected by many nations over the past 12 years and which will be used in ice-sheet modelling experiments to predict the flow of ice and its reaction to global warming [1].
2. The establishment that the Weddell Sea sector of the West Antarctic ice sheet has undergone extensive recent (last few centuries) change, suggesting its continued vulnerability to change [2].
3. Predictive modelling investigations of the Weddell Sea sector of West Antarctica, revealing it to be highly susceptible to irreversible change, and showing how change here will double predictions of global sea-level over the subsequent 100 years [3].
4. Discovery of preglacial surfaces in West Antarctica, demonstrating the ice sheet flow is affected by a topography legacy inherited from the mid-Miocene (~15 million years ago) [4].
5. Discovery of major water channels beneath the West Antarctic ice sheet, caused by former (ancient) ice sheet processes and instructive of that Greenland-style ice sheet processes (ie, surface melting) have operated in Antarctica in the past (during the Pliocene, 3.5 million years ago) [5].

Impact

In Decemer 2013 I was awarded the Martha T Muse Prize for Antarctic Science and Policy by the Tinker Foundation. In April 2014 I helped convene the Scientific Committee on Antarctic Research’s 20-year horizon scanning exercise, which will define how we address the major scientific questions over the next decades, and the innovation and logistics requirements that are necessary. I am convening the UK’s response to this international exercise at the Royal Society on 27^th October.

My work on sea-level change benefits from collaboration with Prof. Tony Payne at Bristol; a lead author on the IPCC sea level chapter, and a co-author of an upcoming Grantham Briefing Note to be written and published in 2015.

Future direction of research

My research plans involve the direct measurement and sampling of subglacial environments, to seek a record of West Antarctic ice sheet history; the timing of the last collapse of the ice sheet being highly pertinent to predictions of its future change.

I am planning long-range airborne geophysical survey across a hitherto uncharted section of the ice sheet, to obtain important boundary conditions for ice flow models.

I also aim to undertake ground-based geophysical measurements in West Antarctica, to understand ice flow processes important for ice sheet stability.

Finally, I am involved in glaciolgical projects in both Greenland and the Canadian High Arctic, assessing the sensitivity of these ice masses to atmospheric and ocean warming.

[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., Furukawa, T., Gogineni, P., Griggs, J.A., Hamilton, G., Hindmarsh, R.C.A., Holmlund, P., Holt, J.W., Jacobel, R.W., Jenkins, A., Jokat, W., Jordan, T., King, E.C., Krabill, W., Riger-Kusk, M., Tinto, K., Langley, K.A., Leitchenkov, G., Luyendyk, B.P., Matsuoka, K., Nixdorf, U., Nogi, Y., Nost, O.A., Popov, S.V., Rignot, E., Rippin, D., Riviera, A., Ross, N., Siegert, M.J., Shibuya, K., Smith, A.M., Steinhage, D., Studinger, M., Sun, B., Thomas, R.H., Tabacco, I., Welch, B., Young, D.A., Xiangbin, C., Zirizzotti, A. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. The Cryosphere. 7, 375–393, 2013. www.the-cryosphere.net/7/375/2013/ doi:10.5194/tc-7-375-2013 (2013).

[2] Siegert, M.J., Ross, N., Corr, H., Kingslake, J., Hindmarsh, R. Late Holocene ice-flow reconfiguration in the Weddell Sea sector of West Antarctica. Quaternary Science Reviews, 78, 98-107 doi: 10.1016/j.quascirev.2013.08.003 (2013).

[3] Wright, A.P., A. M. LeBrocq, S. L. Cornford, R.G. Bingham, H.F.J. Corr, F.Ferroccioliu, T.A. Jordan, A.J. Payne, D.M. Rippin, N. Ross and M. J. Siegert. Sensitivity of the Weddell Sea sector ice streams to sub-shelf melting and surface accumulation. The Cryosphere, 8, 2119-2134 doi:10.5194/tc-8-2119-2014 (2014).

[4] Rose, K.C., Ross, N., Bingham, R.G., Corr, H., Ferraccioli, F., Jordan, T.A., Le Brocq, A., Rippin, D.M., and Siegert, M.J. Ancient pre-glacial erosion surfaces preserved beneath the West Antarctic ice sheet. Earth Surface Dynamics (in review).

[5] Rose, K.C., Ross, N., Bingham, R.G., Corr, H.F.J., Ferraccioli, F., Jordan, T.A., Le Brocq, A., Rippin, D.M. and Siegert, M.J. A temperate former West Antarctic ice sheet suggested by an extensive zone of bed channels. Geology, 42, 971-974. dri: 2014343, doi:10.1130/G35980.1 (2014).