Imperial College London

ProfessorMartinSiegert

Faculty of Natural SciencesThe Grantham Institute for Climate Change

Visiting Professor
 
 
 
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Contact

 

+44 (0)20 7594 9666m.siegert Website

 
 
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Assistant

 

Ms Gosia Gayer +44 (0)20 7594 9666

 
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Location

 

Grantham Directors OfficeSherfield BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

333 results found

Marschalek JW, Blard PH, Sarigulyan E, Ehrmann W, Hemming SR, Thomson SN, Hillenbrand CD, Licht K, Tison JL, Ardoin L, Fripiat F, Allen CS, Marrocchi Y, Siegert MJ, van de Flierdt Tet al., 2024, Byrd Ice Core Debris Constrains the Sediment Provenance Signature of Central West Antarctica, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276

Provenance records from sediments deposited offshore of the West Antarctic Ice Sheet (WAIS) can help identify past major ice retreat, thus constraining ice-sheet models projecting future sea-level rise. Interpretations from such records are, however, hampered by the ice obscuring Antarctica's geology. Here, we explore central West Antarctica's subglacial geology using basal debris from within the Byrd ice core, drilled to the bed in 1968. Sand grain microtextures and a high kaolinite content (∼38–42%) reveal the debris consists predominantly of eroded sedimentary detritus, likely deposited initially in a warm, pre-Oligocene, subaerial environment. Detrital hornblende 40Ar/39Ar ages suggest proximal late Cenozoic subglacial volcanism. The debris has a distinct provenance signature, with: common Permian-Early Jurassic mineral grains; absent early Ross Orogeny grains; a high kaolinite content; and high 143Nd/144Nd and low 87Sr/86Sr ratios. Detecting this “fingerprint” in Antarctic sedimentary records could imply major WAIS retreat, revealing the WAIS's sensitivity to future warming.

Journal article

Jamieson SSR, Ross N, Paxman GJG, Clubb FJ, Young DA, Yan S, Greenbaum J, Blankenship DD, Siegert MJet al., 2023, An ancient river landscape preserved beneath the East Antarctic Ice Sheet., Nat Commun, Vol: 14

The East Antarctic Ice Sheet (EAIS) has its origins ca. 34 million years ago. Since then, the impact of climate change and past fluctuations in the EAIS margin has been reflected in periods of extensive vs. restricted ice cover and the modification of much of the Antarctic landscape. Resolving processes of landscape evolution is therefore critical for establishing ice sheet history, but it is rare to find unmodified landscapes that record past ice conditions. Here, we discover an extensive relic pre-glacial landscape preserved beneath the central EAIS despite millions of years of ice cover. The landscape was formed by rivers prior to ice sheet build-up but later modified by local glaciation before being dissected by outlet glaciers at the margin of a restricted ice sheet. Preservation of the relic surfaces indicates an absence of significant warm-based ice throughout their history, suggesting any transitions between restricted and expanded ice were rapid.

Journal article

Aitken ARA, Li L, Kulessa B, Schroeder D, Jordan TA, Whittaker JM, Anandakrishnan S, Dawson EJ, Wiens DA, Eisen O, Siegert MJet al., 2023, Antarctic Sedimentary Basins and Their Influence on Ice-Sheet Dynamics, REVIEWS OF GEOPHYSICS, Vol: 61, ISSN: 8755-1209

Journal article

Siegert MJ, Bentley MJ, Atkinson A, Bracegirdle TJ, Convey P, Davies B, Downie R, Hogg AE, Holmes C, Hughes KA, Meredith MP, Ross N, Rumble J, Wilkinson Jet al., 2023, Antarctic extreme events, FRONTIERS IN ENVIRONMENTAL SCIENCE, Vol: 11

Journal article

Fremand AC, Fretwell P, Bodart JA, Pritchard HD, Aitken A, Bamber JL, Bell R, Bianchi C, Bingham RG, Blankenship DD, Casassa G, Catania G, Christianson K, Conway H, Corr HFJ, Cui X, Damaske D, Damm V, Drews R, Eagles G, Eisen O, Eisermann H, Ferraccioli F, Field E, Forsberg R, Franke S, Fujita S, Gim Y, Goel V, Gogineni SP, Greenbaum J, Hills B, Hindmarsh RCA, Hoffman AO, Holmlund P, Holschuh N, Holt JW, Horlings AN, Humbert A, Jacobel RW, Jansen D, Jenkins A, Jokat W, Jordan T, King E, Kohler J, Krabill W, Gillespie MK, Langley K, Lee J, Leitchenkov G, Leuschen C, Luyendyk B, MacGregor J, MacKie E, Matsuoka K, Morlighem M, Mouginot J, Nitsche FO, Nogi Y, Nost OA, Paden J, Pattyn F, Popov SV, Rignot E, Rippin DM, Rivera A, Roberts J, Ross N, Ruppel A, Schroeder DM, Siegert MJ, Smith AM, Steinhage D, Studinger M, Sun B, Tabacco I, Tinto K, Urbini S, Vaughan D, Welch BC, Wilson DS, Young DA, Zirizzotti Aet al., 2023, Antarctic Bedmap data: Findable, Accessible, Interoperable, and Reusable (FAIR) sharing of 60 years of ice bed, surface, and thickness data, EARTH SYSTEM SCIENCE DATA, Vol: 15, Pages: 2695-2710, ISSN: 1866-3508

Journal article

Clayton T, Duddu R, Siegert M, Martinez-Pañeda Eet al., 2023, Phase field modelling of glacial crevasses subject to meltwater-driven hydro-fracture

<jats:p>Surface crevasses are predominately mode I fractures that penetrate tens of metres deep into grounded glaciers and floating ice shelves. However, elevated surrounding temperatures have resulted in the production of surface meltwater, which accumulates in neighbouring crevasses and applies additional tensile stresses to crack walls. This process is known as hydrofracture; and if sufficient, can promote full thickness crevasse propagation, and lead to iceberg calving events. Net ablation of ice sheets has become of great concern, as it has become the largest contributor to sea-level rise. To overcome the limitations of empirical and analytical approaches to crevasse predictions, we here propose a thermo-dynamically consistent phase field damage model to simulate damage growth in both ice sheets and floating ice shelves using the finite element method.The model incorporates the three elements needed to mechanistically simulate hydrofracture of surface and basal crevasses: (i) a constitutive description of glacier flow, incorporating the non-linear viscous rheology of ice using Glen&amp;#8217;s flow law, (ii) a phase field formulation capable of capturing cracking phenomena of arbitrary complexity, such as 3D crevasse interaction, and (iii) a poro-damage mechanics representation to account for the role of meltwater pressure on crevasse growth. To assess the suitability of the method, we simulated the propagation of surface and basal crevasses within grounded glaciers and floating ice shelves and compared the predicted crevasse depths with analytical methods such as linear elastic fracture mechanics and the Nye zero stressmethod, with results showing good agreement for idealised conditions.ReferencesT. Clayton, R. Duddu, M. Siegert, E. Mart&amp;#237;nez-Pa&amp;#241;eda, A stress-based poro-damage phase fieldmodel for hydrofracturing of creeping glaciers and ice shelves, Engineering Fracture Mechanics272 (2022) 108693&amp;#160;</jats:p>

Other

Scott WI, Kramer SC, Holland PR, Nicholls KW, Siegert MJ, Piggott MDet al., 2023, Towards a fully unstructured ocean model for ice shelf cavity environments: Model development and verification using the Firedrake finite element framework, OCEAN MODELLING, Vol: 182, ISSN: 1463-5003

Journal article

Dow C, Ross N, Jeofry H, Siu K, Siegert Met al., 2022, Antarctic basal environment shaped by high-pressure flow through a subglacial river system, Nature Geoscience, Vol: 15, Pages: 892-898, ISSN: 1752-0894

The stability of ice sheets and their contributions to sea level are modulated by high-pressure water that lubricates the base of the ice, facilitating rapid flow into the ocean. In Antarctica, subglacial processes are poorly characterized, limiting understanding of ice-sheet flow and its sensitivity to climate forcing. Here, using numerical modelling and geophysical data, we provide evidence of extensive, up to 460 km long, dendritically organized subglacial hydrological systems that stretch from the ice-sheet interior to the grounded margin. We show that these channels transport large fluxes (~24 m3 s−1) of freshwater at high pressure, potentially facilitating enhanced ice flow above. The water exits the ice sheet at specific locations, appearing to drive ice-shelf melting in these areas critical for ice-sheet stability. Changes in subglacial channel size can affect the water depth and pressure of the surrounding drainage system up to 100 km either side of the primary channel. Our results demonstrate the importance of incorporating catchment-scale basal hydrology in calculations of ice-sheet flow and in assessments of ice-shelf melt at grounding zones. Thus, understanding how marginal regions of Antarctica operate, and may change in the future, requires knowledge of processes acting within, and initiating from, the ice-sheet interior.

Journal article

Clayton T, Duddu R, Siegert M, Martínez-Pañeda Eet al., 2022, A stress-based poro-damage phase field model for hydrofracturing of creeping glaciers and ice shelves, Engineering Fracture Mechanics, Vol: 272, Pages: 1-24, ISSN: 0013-7944

There is a need for computational models capable of predicting meltwater-assisted crevasse growth in glacial ice. Mass loss from glaciers and ice sheets is the largest contributor to sea-level rise and iceberg calving due to hydrofracture is one of the most prominent yet less understood glacial mass loss processes. To overcome the limitations of empirical and analytical approaches, we here propose a new phase field-based computational framework to simulate crevasse growth in both grounded ice sheets and floating ice shelves. The model incorporates the three elements needed to mechanistically simulate hydrofracture of surface and basal crevasses: (i) a constitutive description incorporating the non-linear viscous rheology of ice, (ii) a phase field formulation capable of capturing cracking phenomena of arbitrary complexity, such as 3D crevasse interaction, and (iii) a poro-damage representation to account for the role of meltwater pressure on crevasse growth. A stress-based phase field model is adopted to reduce the length-scale sensitivity, as needed to tackle the large scales of iceberg calving, and to adequately predict crevasse growth in tensile stress regions of incompressible solids. The potential of the computational framework presented is demonstrated by addressing a number of 2D and 3D case studies, involving single and multiple crevasses, and considering both grounded and floating conditions. The model results show a good agreement with analytical approaches when particularised to the idealised scenarios where these are relevant. More importantly, we demonstrate how the model can be used to provide the first computational predictions of crevasse interactions in floating ice shelves and 3D ice sheets, shedding new light into these phenomena. Also, the creep-assisted nucleation and growth of crevasses is simulated in a realistic geometry, corresponding to the Helheim glacier. The computational framework presented opens new horizons in the modelling of iceberg

Journal article

McCormack FS, Roberts JL, Dow CF, Stål T, Halpin JA, Reading AM, Siegert MJet al., 2022, Fine‐scale geothermal heat flow in Antarctica can increase simulated subglacial melt estimates, Geophysical Research Letters, Vol: 49, Pages: 1-9, ISSN: 0094-8276

Antarctic geothermal heat flow (GHF) affects the thermal regime of ice sheets and simulations of ice and subglacial meltwater discharge to the ocean, but remains poorly constrained. We use an ice sheet model to investigate the impact of GHF anomalies on subglacial meltwater production in the Aurora Subglacial Basin, East Antarctica. We find that spatially-variable GHF fields produce more meltwater than a constant GHF with the same background mean, and meltwater production increases as the resolution of GHF anomalies increases. Our results suggest that model simulations of this region systematically underestimate meltwater production using current GHF models. We determine the minimum basal heating required to bring the basal ice temperature to the pressure melting point, which should be taken together with the scale-length of likely local variability in targeting in-situ GHF field campaigns.

Journal article

Yan S, Blankenship D, Greenbaum J, Young D, Li L, Rutishauser A, Guo J, Roberts J, van Ommen T, Siegert M, Sun Bet al., 2022, A newly discovered subglacial lake in East Antarctica likely hosts a valuable sedimentary record of ice and climate change, Geology (Boulder), Vol: 50, Pages: 949-953, ISSN: 0091-7613

The Princess Elizabeth Land sector of the East Antarctic Ice Sheet is a significant reservoir of grounded ice and is adjacent to regions that experienced great change during Quaternary glacial cycles and Pliocene warm episodes. The existence of an extensive subglacial water system in Princess Elizabeth Land (to date only inferred from satellite imagery) bears the potential to significantly impact the thermal and kinematic conditions of the overlying ice sheet. We confirm the existence of a major subglacial lake, herein referred to as Lake Snow Eagle (LSE), for the first time using recently acquired aerogeophysical data. We systematically investigated LSE’s geological characteristics and bathymetry from two-dimensional geophysical inversion models. The inversion results suggest that LSE is located along a compressional geologic boundary, which provides reference for future characterization of the geologic and tectonic context of this region. We estimate LSE to be ~42 km in length and 370 km2 in area, making it one of the largest subglacial lakes in Antarctica. Additionally, the airborne ice-penetrating radar observations and geophysical inversions reveal a layer of unconsolidated water-saturated sediment around and at the bottom of LSE, which—given the ultralow rates of sedimentation expected in such environments—may archive valuable records of paleoenvironmental changes and the early history of East Antarctic Ice Sheet evolution in Princess Elizabeth Land.

Journal article

Mantelli E, Bryant M, Seroussi H, Raess L, Castelletti D, Schroeder D, Suckale J, Siegert Met al., 2022, Layer geometry as a constraint on the physics of sliding onset

<jats:p>&amp;lt;p&amp;gt;Transitions from basal no slip to basal sliding are a common feature of ice sheets, yet one that has remained difficult to observe. In this study we leverage recent advances in the processing of radar sounding data to study these transitions through their signature in englacial layers. Englacial layers encode information about strain and velocity, and the relation between their geometry and the onset of basal sliding has been demonstrated in ice flow models (the so-called &amp;quot;Weertman effect&amp;quot;). Here we leverage this relation to test the long-standing hypothesis that sliding onset takes the form of an abrupt no slip/sliding transition. By comparing the modeled signature of an abrupt sliding onset in englacial layer slopes against slope observations from the onset region of a West Antarctic ice stream (Institute Ice Stream), we conclude that observed layer geometry does not support an abrupt no slip/sliding transition. Our findings instead suggest a much smoother sliding onset, as would be consistent with temperature-dependent friction between ice and bed. Direct measurements of basal temperature at the catchment scale would allow us to confirm this hypothesis.&amp;lt;/p&amp;gt;</jats:p>

Journal article

Scott W, Kramer S, Yeager B, Holland P, Nicholls KW, Siegert M, Piggott Met al., 2022, First steps for a 3d flexible, unstructured finite element ocean model for flow under ice shelf cavities: an ISOMIP+ case study

<jats:p>&amp;lt;p&amp;gt;Accurate modelling of basal melting beneath ice shelves is key to reducing the uncertainty in forecasts of ice-shelf stability and, thus, the Antarctic contribution to sea level rise. However, the lack of flexibility inherent to traditional ocean models can pose problems.&amp;lt;em&amp;gt; &amp;lt;/em&amp;gt;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Obtaining accurate melt estimates requires capturing the turbulent exchange of momentum, heat and salt at the ice-ocean interface, which may be modulated by the competing effects of stratification and basal slope. There are still significant uncertainties surrounding the trade-off between the simplicity of the melt parameterisation and the processes that need to be resolved by the numerical ocean model near the boundary.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Real ice-shelf cavity geometries are complicated. Bathymetric valleys are common and provide pathways for warm circumpolar deep water. The ice base is marked by channels, crevasses and terraces. These features will affect the boundary flow, with an added complication that melting plays a role in their formation. It is very difficult to model such flow regimes using a traditional ocean model not only because of the resolution constraints imposed by inflexible grids, but also due to the inbuilt assumptions of large aspect ratio processes and domains that may be violated when flow occurs past these features.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Ice flow models are very sensitive to how they are forced by melting at the grounding line, where the ice starts to float. The grounding line is precisely the region where ocean models are most questionable due to insufficient resolution imposed by limitations on the grid. Subglacial outflow into the cavity will likely break the inherent physical assumptions of hydrostatic, non-negligible vertical accelerations in large aspect ratio domains.&

Journal article

Marschalek J, Gasson E, van de Flierdt T, Hillenbrand C-D, Siegert Met al., 2022, A Path to Quantitative Interpretation of Antarctic Sediment Provenance Records

<jats:p>&amp;lt;p&amp;gt;Tracing the provenance of Antarctic sediments yields unique insights into the form and flow of past ice sheets. However, sediment provenance studies are typically limited to qualitative interpretations by uncertainties regarding subglacial geology, glacial erosion, and transport of sediment both subglacially and beyond the ice sheet margin. Here, we forward model marine geochemical sediment provenance data, in particular neodymium isotope ratios. Numerical ice-sheet modelling predicts the spatial pattern of subglacial erosion rates for a given ice sheet configuration, then ice flow paths are traced to the ice sheet margin. For the modern ice sheet, simple approximations of glacimarine sediment transport processes produce a good agreement with Holocene surface sediments in many areas of glaciological interest. Calibrating our model to the modern setting permits application of the approach to past ice sheet configurations, which show that large changes to sediment provenance over time can be reconstructed around the West Antarctic margin. This first step towards greater integration of Antarctic sediment provenance data with numerical modelling offers the potential for advances in both fields.&amp;lt;/p&amp;gt;</jats:p>

Journal article

Aitken ARA, Li L, Kulessa B, Schroeder DM, Jordan TA, Whittaker JM, Anandakrishnan S, Wiens DA, Eisen O, Siegert MJet al., 2022, Antarctica's subglacial sedimentary basins and their influence on ice-sheet change

Journal article

Livingstone SJ, Li Y, Rutishauser A, Sanderson RJ, Winter K, Mikucki JA, Bjornsson H, Bowling JS, Chu W, Dow CF, Fricker HA, McMillan M, Ng FSL, Ross N, Siegert MJ, Siegfried M, Sole AJet al., 2022, Subglacial lakes and their changing role in a warming climate (Jan, 10.1038/s43017-021-00246-9, 2022), NATURE REVIEWS EARTH & ENVIRONMENT, Vol: 3, Pages: 156-156

Journal article

Spencer R, Hubbard G, Rowcroft P, Baribeau J, Bennett G, Ciais P, Carver C, Chang J, Gill S, Grinyer N, Peachey J, Philipson C, Puhl I, Rooney P, Rumsey S, Siegert M, Tear T, Young Pet al., 2022, Technical Advances in Assessing Natural Climate Solutions for Global Carbon Markets, Technical Advances in Assessing Natural Climate Solutions for Global Carbon Markets, Publisher: Sustainable Markets Initiative

The Terra Carta serves as the guiding mandate for HRH The Prince of Wales’ Sustainable Markets Initiative (SMI).1 It calls for urgent action to build a sustainable future for Nature, People and Planet. Investments in natural climate solutions can simultaneously address each of these pillars. The SMI Science Working Group aims to connect nature, science, and technology in addressing root challenges to scaling natural climate solutions. The need for urgent action on global warming is now widely considered one of the most critical environmental issues of our time, alongside biodiversity loss. While rapid decarbonisation of the global economy is an essential condition for limiting the rise in global temperatures to no more than 1.5°C above pre-industrial levels, it is also increasingly recognised that well-designed natural climate solutions can make an important contribution to limiting climate change, while concurrently providing valuable community and biodiversity benefits, if deployed early enough and at scale. Despite the potential these solutions offer, investments in natural climate solutions fall far short of that required to make a meaningful contribution to climate change mitigation. The lack of investment can, at least in part, be attributed to uncertainties and risks concerning both the role of natural climate solutions and the integrity of credits traded in voluntary carbon markets. This paper argues that recent advances in scientific understanding and technological developments have resulted in substantial improvements in the scale, frequency and accuracy with which the extent and condition of natural capital assets and their actual carbon performance can be assessed. This is particularly the case with respect to forests, which is where a lot of the technological assessment improvements have been achieved recently. The full potential of these technology platforms for natural climate solutions assessment cannot be fully realised wi

Report

Livingstone SJ, Li Y, Rutishauser A, Sanderson RJ, Winter K, Mikucki JA, Bjornsson H, Bowling JS, Chu W, Dow CF, Fricker HA, McMillan M, Ng FSL, Ross N, Siegert MJ, Siegfried M, Sole AJet al., 2022, Subglacial lakes and their changing role in a warming climate, Nature Reviews Earth & Environment, Vol: 3, Pages: 106-124, ISSN: 2662-138X

Subglacial lakes are repositories of ancient climate conditions, provide habitats for life and modulate ice flow, basal hydrology, biogeochemical fluxes and geomorphic activity. In this Review, we construct the first global inventory of subglacial lakes (773 in total), which includes 675 from Antarctica (59 newly identified), 64 from Greenland, 2 beneath the Devon Ice Cap, 6 beneath Iceland’s ice caps and 26 from valley glaciers. This inventory is used to evaluate subglacial lake environments, dynamics and their wider impact on ice flow and sediment transport. The behaviour of these lakes is conditioned by their subglacial setting and the hydrological, dynamic and mass balance regime of the overlying ice mass. Regions where climate warming causes ice surface steepening are predicted to have fewer and smaller lakes, but increased activity with higher discharge drainages of shorter duration. Coupling to surface melt and rainfall inputs will modulate fill–drain cycles and seasonally enhance oxic processes. Higher discharges cause large, transient ice flow accelerations but might result in overall net slowdown owing to the development of efficient subglacial drainage. Subglacial lake research requires new drilling technologies and the integration of geophysics, satellite monitoring and numerical modelling to provide insight into the wider role of subglacial lakes in the changing Earth system.

Journal article

Lang S, Yang M, Cui X, Li L, Cai Y, Liu X, Guo J, Sun B, Siegert Met al., 2022, A Semiautomatic Method for Predicting Subglacial Dry and Wet Zones Through Identifying Dry-Wet Transitions, IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, Vol: 60, ISSN: 0196-2892

Journal article

Marschalek J, Zurli L, Talarico F, van de Flierdt T, Vermeesch P, Carter A, Beny F, Bout-Roumazeilles V, Sangiorgi F, Hemming S, Perez L, Colleoni F, Prebble J, van Peer T, Perotti M, Shevenell A, Browne I, Kulhanek D, Levy R, Harwood D, Sullivan N, Meyers S, Griffith E, Hillenbrand C-D, Gasson E, Siegert M, Keisling B, Licht K, Kuhn G, Dodd J, Boshuis C, De Santis L, McKay Ret al., 2021, A large West Antarctic Ice Sheet explains Early Neogene sea-level amplitude, Nature, Vol: 600, Pages: 450-455, ISSN: 0028-0836

Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from far-field records are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here, we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution.

Journal article

Siegert M, 2021, Frontiers in environmental science – editor’s picks 2021, Publisher: Frontiers Media SA, ISBN: 9782889716722

Book

Florindo F, Meloni A, Siegert M, 2021, Sixty-years of Coordination and Support for Antarctic-Science - The role of SCAR, Antarctic Climate Evolution, Editors: Florindo, Siegert, De Santis, Naish, Publisher: Elsevier, Pages: 9-40, ISBN: 9780128191095

Antarctic Climate Evolution (ACE) and Past Antarctic Ice Sheet (PAIS) have been two major and successful Scientific Research Programs of SCAR (Scientific Committee on Antarctic Research), with important achievements concerning the ice and climate evolution of the Antarctic continent and its surrounding seas through the Cenozoic era to the present day. SCAR held its first formal meeting in 1958 and from then onwards it has succeeded admirably in facilitating scientific interactions between nations, in helping the scientific community make significant breakthroughs in understanding the processes at work on the continent and in the Southern ocean, and – as a non governmental organization – in playing an important role in providing impartial scientific advice to the Parties to the Antarctic Treaty, and in influencing the scientific aspects of Antarctic governance. SCAR adds value to national scientific activities by addressing topics covering the whole of Antarctica or the surrounding Southern Ocean in ways impossible for any one nation to achieve alone. This report discusses briefly the key ways in which SCAR has supported and coordinated scientific research in Antarctica.

Book chapter

Florindo F, Siegert M, De Santis L, Naish Tet al., 2021, Antarctic Climate Evolution – second edition, Antarctic Climate Evolution - second edition, Editors: Florindo, Siegert, De Santis, Naish, Publisher: Elsevier, Pages: 1-8, ISBN: 9780128191101

Antarctic Climate Evolution second edition is a result of both SCAR programmes and documents the state of knowledge concerning the ice and climate evolution of the Antarctic continent and its surrounding seas through the Cenozoic era to present day and into the future. Most of the subcommittees in ACE and PAIS have been responsible for individual chapters and, in this way, we have been able to cover the complete history of the Antarctic Ice Sheet and its climate evolution. The book will be of interest to research scientists from a wide range of disciplines including glaciology, palaeoclimatology, sedimentology, climate change, environmental science, oceanography and palaeontology. It will alsobe valuable as a supplementary text for undergraduate courses.

Book chapter

Siegert M, Golledge N, 2021, Advances in numerical modelling of the Antarctic ice sheet, Antarctic Climate Evolutio - second edition, Editors: Florindo, Siegert, De Santis, Naish, Publisher: Elsevier, ISBN: 9780128191095

While geological evidence provides the clearest means to evaluate past Antarctic ice sheet change, quantification of the processes by which such change occurred can only be done through modelling. Continental-scale ice sheet modelling has been used extensively to understand how past ice-sheets have responded to environmental forcing. Such work has revealed how past ice-sheet configurations are possible glaciologically and climatically, and the rates at which changes can occur. The past 10 years have seen considerable advances in numerical ice-sheet modelling, the data used to force and calibrate them, and in the identification of the glaciological processes needed to improve them. As a result, several studies have improved our understanding of how and why the Antarctic ice sheet has changed since its initiation ~34 Ma, with key episodes being the Pliocene, Pleistocene and Last Glacial Maximum. Here, we review some of these advances as a guide to how ice sheet modelling is helping to shape our knowledge of how Antarctica responds to external forcing.

Book chapter

Siegert M, Florindo F, De Santis L, Naish Tet al., 2021, The future evolution of Antarctic climate: conclusions and upcoming programmes, Antarctic Climate Evolution - second edition, Editors: Florindo, Siegert, De Santis, Naish, Publisher: Elsevier, Pages: 769-776, ISBN: 9780128191095

Our appreciation of Antarctic climate evolution has grown significantly in the last decade. Characterised by international cooperation, and leadership from the Scientific Committee on Antarctic Research (SCAR), we now have better understanding of how and why Antarctica's ice sheets have developed and influenced global climate change. While the nature of, and explanations for, significant glacial events has improved, gaps in our knowledge of the rate and impact of processes responsible remain. Such processes are critical if we are to understand how the palaeo record can inform us about the vulnerability of the Antarctic ice sheet during periods of greenhouse-gas driven warming. Hence, establishing further precision of past changes, at a resolution helpful to process-based modelling is an important next step to better constraining future Antarctic change and its sea-level consequences.

Book chapter

Siegert M, Hein A, White D, Gore D, De Santis L, Hillenbrand C-Det al., 2021, Antarctic ice sheet changes since the Last Glacial Maximum, Antarctic Climate Evolution - second edition, Editors: Florindo, Siegert, De Santis, Naish, Publisher: Elsevier, Pages: 621-682, ISBN: 9780128191095

Technological advances in the study and dating of both land and marine glacial geologic features, combined with both glaciological and post-glacial isostatic rebound modelling, have developed knowledge and understanding of the Antarctic ice sheets at the Last Glacial Maximum (LGM) and their subsequent changes. Here, we review geological evidence for the extent and timing of the maximum advance of the East and West Antarctic ice sheets and the Antarctic Peninsula Ice Sheet during the most recent glacial cycle. We also discuss evidence for the rate and timing of post-LGM ice-sheet retreat. Geological data provide a very important ‘first-hand’ record of ice-sheet changes over a range of time periods. They are also useful for constraining and improving models that have the potential to both fill in the gaps where geological data are unavailable, and to make predictions about the future. In reviewing the glacial geological evidence, we provide a benchmark against which future ice-sheet modelling exercises can be assessed.

Book chapter

Siegert M, Marschalek J, Plaschkes C, 2021, The future of UK Antarctic science: strategic priorities essential needs and opportunities for international leadership

• The Antarctic region has been experiencing rapid change in recent decadesdue to human induced factors. Most notably, climate heating is causing icesheet melting, leading to sea level rise and disruption in global ocean heatcirculation, with far-reaching global consequences.• At the same time, this region holds unique research potential that can helpaddress a range of critically important scientific priorities, including climatechange impacts, ecosystem protection, the likelihood of extra-terrestrial lifeand monitoring of space debris.• Due to its long and impressive record of Antarctic research and its scientific,engineering and logistical capabilities in the region, the United Kingdom (UK)is strategically well-positioned to lead or play a key role in the delivery of theseresearch priorities.• To achieve this potential, the UK must act collectively and in partnership withothers, as the best and most urgent research benefits from collaboration,cooperation and cost sharing. Crucially, it must mobilise experts both fromwithin the UK and internationally from a range of disciplines, including thesocial sciences. In the twenty-first century, Antarctic research must not existwithin its own bubble

Report

Siegert M, Pearson P, 2021, Reducing uncertainty in 21st century sea-level predictions and beyond, Frontiers in Environmental Science, Vol: 9, ISSN: 2296-665X

Sea-level rise is one of the most critical issues the world faces under global warming. Around 680 million people (10% of the world’s population) live in low-lying coastal regions that are susceptible to flooding through storm surges and from sea-water infiltration of fresh groundwater reserves, degradation of farmland and accelerated coastal erosion, among other impacts. Rising sea level will exacerbate these problems and lead to societal impacts ranging from crop and water-supply failures to breakdowns of city infrastructures. In time, it is likely such changes will necessitate the migration of people with substantial economic cost and social upheaval. Here, we discuss the physical processes influencing 21st Century sea-level rise, the importance of not using 2100 alone as a benchmark, the changes that are already locked in, especially after 2100, and those that can be avoided. We also consider the need for both adaptation and mitigation measures and early warning systems in this challenging global problem. Finally, we discuss how the scientific prediction of sea level rise can improved through international coordination, cooperation and cost sharing.

Journal article

Siegert M, 2021, The net-zero carbon transition, Enterprise Risk – the magazine of the Institute of Risk Managers

Journal article

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