The increasing availability of remotely sensed observations and computational capacity, drive modelling and observational glacier studies towards increasingly large spatial scales. These large scales are of particular relevance, as they impact policy decisions and public discourse. In the European Alps, for instance, glacier changes are important from a touristic perspective, while in High Mountain Asia, glaciers are a key in the region’s hydrological cycle. At a global scale, glaciers are among the most important contributors to present-day sea level change.

This session focuses on advances in observing and modelling mountain glaciers and ice caps at the regional to global scale. We invite both observation- and modelling-based contributions that lead to a more complete understanding of glacier changes and dynamics at such scales.

Contributions may include, but are not limited to, the following topics:
• Observation and modelling results revealing previously unappreciated regional differences in glacier changes or in their dynamics;
• Large-scale impact studies, including glaciers' contribution to sea level change, or changes in water availability from glacierized regions;
• Advances in regional- to global-scale glacier models, e.g. inclusion of physical processes such as ice dynamics, debris-cover effects, glacier calving, or glacier surging;
• Regional to global scale process-studies, based on remote sensing observations or meta-analyses of ground-based data;
• Innovative combinations of observation and modelling techniques, for example blending different remote sensing products, or integrating machine learning algorithms;
• Inverse modelling of subglacial characteristics or glacier ice thickness at regional scales.

Note that this session is organized as a PICO.

Public information:
1) The session will be fully virtual and will be based on "zoom" (https://zoom.us/).
2) The corresponding zoom-link will be posted through the session's chat as soon as the chat is open. You will be able to join the session by clicking on the corresponding link.
3) If you want to test zoom before that, visit https://zoom.us/test
4) The session will start with a brief introduction given by the conveners, who will then pass the word to the invited speaker, Michael Zemp.
5) The individual presenters will follow suite with 2-minute pitch talks -- very much as in a "normal PICO session! The sequence is given by the session's programme.
6) After the pitches, a "zoom break-out room" will be available for every presenter. "Break out rooms" are a video-conference environment for sub-sets of meeting attendees. Every participant will be able to choose the room (s)he is most interested in, and be able to visit different rooms if wished -- again, very much as in a normal PICO session!

We very much encourage to have a look at the individual displays before the start of the session and to use the comment functionality to engage in the discussion.
We are looking forward to an exciting session!

This session is intended to attract a broad range of ice-sheet and glacier modelling contributions, welcoming applied and theoretical contributions. Theoretical topics that are encouraged are higher-order mechanical models, data inversion and assimilation, representation of other earth sub-systems in ice-sheet models, and the incorporation of basal processes and novel constitutive relationships in these models.

Applications of newer modelling themes to ice-sheets and glaciers past and present are particularly encouraged, in particular those considering ice streams, rapid change, grounding line motion and ice-sheet model intercomparisons.

Ice sheets play an active role in the climate system by amplifying, pacing, and potentially driving global climate change over a wide range of time scales. The impact of interactions between ice sheets and climate include changes in atmospheric and ocean temperatures and circulation, global biogeochemical cycles, the global hydrological cycle, vegetation, sea level, and land-surface albedo, which in turn cause additional feedbacks in the climate system. This session will present data and modelling results that examine ice sheet interactions with other components of the climate system over several time scales. Among other topics, issues to be addressed in this session include ice sheet-climate interactions from glacial-interglacial to millennial and centennial time scales, the role of ice sheets in Cenozoic global cooling and the mid-Pleistocene transition, reconstructions of past ice sheets and sea level, the current and future evolution of the ice sheets, and the role of ice sheets in abrupt climate change.

Public information:
We have decided to organise the chat in two parts:

1. During the first part we will go through the existing displays in order and have 5 minutes for each to answer questions from the participants.
Preliminary schedule below. Since we don't know yet the final number of displays available this timing may still change.

10:45 Intro
10:50 D2558 EGU2020-15058 Did a Beringian ice sheet once exist?
10:55 D2559 EGU2020-5912 Global coupled climate - ice sheet model simulations for the penultimate deglaciation and the last interglacial
11:00 D2561 EGU2020-7844 Impact of mid-glacial ice sheets on the recovery time of the AMOC: Implications on the frequent DO cycles during the mid-glacial period
11:05 D2562 EGU2020-18683 Modelling the surface mass balance of the Greenland Ice Sheet from 6000 BP to the year 2200
11:10 D2563 EGU2020-10601 Greenland ice sheet contribution to 21st century sea level rise as modelled by the coupled CESM2.1-CISM2.1
11:15 D2564 EGU2020-20368 The North Atlantic Oscillation and the Greenland ice sheet in CMIP6
11:20 D2566 EGU2020-5647 A circumpolar coupled ocean – Antarctic ice sheet configuration for investigating recent changes in Southern Ocean heat content
11:25 D2567 EGU2020-2272 Transient Pleistocene simulations with a new coupled climate-ice-sheet model
11:30 D2568 EGU2020-16221 Comparison of peri-Antarctic sub-shelf melt rates in coupled and uncoupled ice-sheet model simulations
11:35 D2570 EGU2020-10255 Coupling the Parallel Ice Sheet Model with the Modular Ocean Model via an Antarctic ice-shelf cavity module
11:40 D2572 EGU2020-11625 AMOC recovery in a multi-centennial scenario using a coupled atmosphere-ocean-ice sheet model
11:45 D2574 EGU2020-21261 The ocean response to changes of the Greenland Ice sheet in a warming climate
11:50 D2577 EGU2020-16815 Dynamic Hydrological Discharge and Lake Modelling for Coupled Climate Model Simulations of the Last Glacial Cycle
11:55 D2578 EGU2020-21686 Greenland ice sheet surface mass balance response to high CO2 forcing: threshold and mechanisms for accelerated surface mass loss
12:00 D2579 EGU2020-17514 A global ensemble-based comparison of the last two glacial inceptions with LCice 2.0

2. Time permitting, we were hoping to discuss a few key questions as an open chat with everybody (authors and participants) around the theme of our session: Ice-sheet and climate interactions. Of course, these discussions are just a starter and we encourage everyone to keep communicating and discussing via other media after the session.

Some examples:

- What is the most important progress in ice sheet-climate model
coupling in the last 5 years? (distinguish paleo and future perspective).

- What model improvement is necessary to address outstanding scientific
questions?

- Where do you see important gaps in our knowledge that should be addressed?

- What observational data has had an important impact on our
understanding of ice sheet-climate interactions?

- What paleo archives (kind, location, time frame) would be the most
important to examine/extend to improve our knowledge about ice
sheet-climate interactions?

Please remember that the chat will not be preserved. Comments and questions on individual displays (that have not been answered) are best posted in the online discussion under the display abstracts. Public discussion and feedback of presentation materials is open to 31 May.

Ice shelves and tidewater glaciers are sensitive elements of the climate system. Sandwiched between atmosphere and ocean, they are vulnerable to changes in either. The recent disintegration of ice shelves such as Larsen B and Wilkins on the Antarctic Peninsula, current thinning of the ice shelves in the Amundsen Sea sector of West Antarctica, and the recent accelerations of many of Greenland's tidewater glaciers provide evidence of the rapidity with which those systems can respond. Changes in marine-terminating outlets appear to be intimately linked with acceleration and thinning of the ice sheets inland of the grounding line, with immediate consequences for global sea level. Studies of the dynamics and structure of the ice sheets' marine termini and their interactions with atmosphere and ocean are the key to improving our understanding of their response to climate forcing and of their buttressing role for ice streams. The main themes of this session are the dynamics of ice shelves and tidewater glaciers and their interaction with the ocean, atmosphere and the inland ice, including grounding line dynamics. The session includes studies on related processes such as calving, ice fracture, rifting and mass balance, as well as theoretical descriptions of mechanical and thermodynamic processes. We seek contributions both from numerical modelling of ice shelves and tidewater glaciers, including their oceanic and atmospheric environments, and from observational studies of those systems, including glaciological and oceanographic field measurements, as well as remote sensing and laboratory studies.

Dynamic subglacial and supraglacial water networks play a key role in the flow and stability of ice sheets. The accumulation of meltwater on the surface of ice shelves has been hypothesized as a potential mechanism controlling ice-shelf stability, with ice-shelf collapse triggering substantial increases in discharge of grounded ice. Observations and modelling also suggest that complex hydrological networks occur at the base of glaciers and these systems play a prominent role in controlling the flow of grounded ice. This session tackles the urgent need to better understand the fundamental processes involved in glacial hydrology that need to be addressed in order to accurately predict future ice-sheet evolution and mass loss, and ultimately the contribution to sea-level rise .
We seek contributions from both the modelling and observational communities relating to any area of ice-sheet hydrology. This includes but is not limited to: surface hydrology, melt lake and river formation; meltwater processes within the ice and firn; basal hydrology; subglacial lakes; impacts of meltwater on ice-sheet stability and flow; incorporation of any of these processes into large-scale climate and ice-sheet models.

Subglacial environments are among the least accessible regions on Earth and represent one of the last physical frontiers of glaciological research, while emerging as a unique ecological habitat. The subglacial environment is a key component in the dynamic behaviour of ice sheets and glaciers, involving complex and precise mass and energy transfers between the ice and its substrate of water, air, bedrock, or sediment, and the oceans at ice sheet boundaries. In particular, determining the distribution and nature of water flows at the ice-mass bed is highlighted as a priority for understanding and predicting ice dynamics. For example, both remote sensing and ground-based observations across Antarctica and Greenland highlight the existence of subglacial water in a variety of forms, ranging from vast subglacial lakes (providing distinctive habitats for potentially unique life forms) to mm-thick water flows at the ice-substrate interface. Feedbacks between increased surface melting, glacier bed conditions and ice flow also affect alpine glaciers, potentially contributing to increased glacial retreat in low and mid-latitude mountain regions.

It is clear that subglacial processes impact ice dynamics, transcending ice-mass scales from valley glaciers to large ice sheets and, through feedback loops, contribute to changes in sea level, ocean circulation, and climate evolution. Quantitative characterisation of the basal environment therefore remains an outstanding glaciological problem, as does scaling of this knowledge for use in modelling ice sheet and glacier behaviour.

We invite scientific contributions that include, but are not limited to, measurements and/or modelling of: (i) flow of subglacial water at the bed and through subglacial sediments; (ii) linkages between subglacial hydrology and ice dynamics; (iii) theoretical-, field-, or laboratory-based parameterisation of subglacial processes in numerical ice-flow models; (v) formation, geometry and potential hydrological linkages between subglacial lakes; (v) subglacial and supraglacial lake drainage and subglacial floods from ice margins; and (vi) geomorphological evidence of subglacial water flows from contemporary ice-sheet margins and across formerly glaciated continental-scale regions.