Mountain glaciers and ice caps are major contributors to sea-level rise and have large impacts on water balance of local basins. This is a general session on glaciers and ice caps where the relationship to climate forms a particular focus. The IPCC AR5 of Working Group 1 covers Earths Glaciers and Ice Caps outside the ice sheets under the heading of Glaciers and shows that, despite much progress recently provided by the community, we are still left with substantial unknowns. We need to acquire more data, both from new fieldwork and release of unpublished data from prior years on mass changes of glaciers and ice caps from all regions of the world. We need to improve the understanding of the processes behind the changes, and we need to improve the application of models of different complexity. We welcome presentations on all aspects of mass changes; current, past and future changes based on field observations, remote sensing and modeling. Studies of physical processes controlling accumulation and ablation including calving and submarine melting, are especially welcome.

Studies of ice extent, volume and dynamics during former glaciations are important for understanding past climates and evolution of the Earth’s surface, and also provide analogies for present-day ice sheets and their subglacial environments. This includes observations of glacial erosion, glacial transport and deposition of sediments, formation of fjords and their relation to ice streams, evidence for migration of ice divides, former locations of subglacial lakes, relations between high geothermal heat flow, basal ice melt and rapid ice flow, and other aspects of paleo glacier extent and behaviour. This session will bring together the interdisciplinary scientific community working on former ice covers from the perspectives of glacial geomorphology, quaternary geology, and numerical modeling. It will provide a forum in which field-based reconstructions and model-based simulations can be compared and contrasted. We particularly welcome contributions that shed light on ancient and more recent glaciations on Earth and their interaction with other components of the Earth System.

To address societal concerns over rising sea level and extreme events, understanding the contributions behind these changes is key to predict potential impacts of sea level change on coastal communities and global economy, and is recognized as one of the Grand Challenges of our time by the World Climate Research Programme (WCRP). To continue this discussion, we welcome contributions from the international sea level community that improve our knowledge of the past and present changes in sea level, extreme events, and flooding, and produce improved predictions of their future changes. We welcome studies on various drivers of sea level change and linkages between variability in sea level, heat and freshwater content, ocean dynamics, land subsidence from natural versus anthropogenic influences, and mass exchange between the land and the ocean associated with ice sheet and glacier mass loss and changes in the terrestrial water storage. Studies focusing on future sea level changes are also encouraged, as well as those discussing potential short-, medium-, and long-term impacts on coastal and deltaic environments, as well as the global oceans.

The millennial-scale variability associated with Dansgaard-Oeschger (D-O) cycles during the last glacial is known to have affected the climate system on a global scale. New high-resolution sediment and ice core proxy records document in increasing detail local and global variability of ice sheets, sea ice, as well as oceanic and atmospheric circulation during the D-O cycles. In addition, insights into the dynamics of the coupled ocean-cryosphere-atmosphere system during the millennial-scale climate cycles are emerging from improved model simulations. Documenting the precise timing and sequence of events in proxy records and capturing the processes responsible for the global pattern of rapid climate changes, which stretch from Greenland to Antarctica, remains a major challenge. However, understanding the underlying dynamics will provide fundamental information on the stability of the global climate system. In this interdisciplinary session, we welcome proxy- and model-based research that tests hypotheses on causes and processes behind the D-O events and helps understanding past, present and future changes to the climate system. The session is hosted by the ERC synergy project ice2ice.

Solicited talks include:
Oeschger medal lecture by Edward Brook, Oregon State University
Marlene Klockmann, Helmholtz-Zentrum Geesthacht Centre
Bradley Markle, University of Washington

The mid-Pleistocene Transition (MPT) is a crucial changes in climate dynamics, leading us into our current regime of long, asymmetric glacial cycles. However, evidence about the differences in how climate behaved before and after the MPT remains sparse and we also lack evidence to decide between theories that aim to explain the MPT. Here we hope to gather new datasets that compare climate on either side of the MPT or that offer new evidence about glacial cycles before it. Modelling and conceptual work about the causes of the MPT are also wlecome. Finally we would like to hear about work that paves the way for new projects, including plans and methodologies to obtain pre-MPT ice cores such as (but not limited to) the IPICS Oldest Ice challenge, like Beyond EPICA and other endeavours.

The Tibetan Plateau and surrounding mountain regions, known as the Third Pole, cover an area of > 5 million km2 and are considered to be the water tower of Asia. The Pan Third Pole expands on both the north-south and the east-west directions, going across the Tibetan Plateau, Pamir, Hindu Kush, Iran Plateau, Caucasian and Carpathian, and covering an area of about 20 million km2. Like the Arctic and Antarctica, the Pan Third Pole’s environment is extremely sensitive to global climate change. In recent years, scientists from around the globe have increased observational, remote sensing and numerical modeling research related to the Pan Third Pole in an effort to quantify and predict past, current and future scenarios. Co-sponsored by TPE (www.tpe.ac.cn), this session is dedicated to studies of Pan Third Pole atmosphere, cryosphere, hydrosphere, and biosphere and their interactions with global change. Related contributions are welcomed.

Mountains cover approximately one quarter of the total land surface on the planet, and a significant fraction of the world’s population lives in their vicinity. Orography critically affects weather and climate processes at all scales and, in connection with factors such as land-cover heterogeneity, is responsible for high spatial variability in mountain weather and climate.

Due to this high complexity, monitoring and modeling the atmosphere and the other components of the climate system in mountain regions is challenging both at short (meteorological) and long (climatological) time-scales. This session is devoted to the better understanding of weather and climate processes in mountain and high-elevation areas around the globe, as well as their modification induced by global environmental change.

We welcome contributions describing the influence of mountains on the atmosphere on meteorological time-scales, including terrain-induced airflow, orographic precipitation, land-atmosphere exchange over mountains, forecasting and predictability of mountain weather. Furthermore we invite studies that investigate climate processes and climate change in mountain areas and its impacts on dependent systems, based on monitoring and modeling activities. Particularly welcome are contributions that merge various sources of information and reach across disciplinary borders (atmospheric, hydrological, cryospheric, ecological and social sciences).

A planned outcome of this session is a summary document providing a mountains perspective and input for the IPCC Sixth Assessment Report, more specifically for Working Group I report on the Physical Sciences Basis and the cross-chapter paper on 'Mountains', which is flagged for the Working Group II report. This summary document is organized and supported by the Mountain Research Initiative (MRI).

The Arctic sea ice and high latitude atmosphere and oceans have experienced significant changes over the modern observational era. The polar climate is crucial for the Earth’s energy and water budget, and its variability and change have direct socio-economic and ecological impacts. Thus, understanding high-latitude variability and improving predictions of high latitude climate is highly important for society. Predictability studies indicate that decadal to multi-decadal variations in the oceans and sub-seasonal to multi-year sea ice variations are the largest sources of predictability in high latitudes. However, dynamical model predictions are not yet in the position to provide us with accurate predictions of the polar climate. Main reasons for this are the lack of observations in high latitudes, insufficient initialization methods and shortcomings of climate models in representing some of the important climate processes in high latitudes.
This session aims for a better understanding and better representation of the mechanisms that control high latitude climate variability and predictability in both hemispheres at sub-seasonal to multi-decadal time-scales in past, recent and future climates. Further, the session aims to discuss ongoing efforts to improve climate predictions at high latitudes at various time scales (as e.g. usage of additional observations for initialization, improved initialization methods, impact of higher resolution, improved parameterizations) and potential teleconnections of high latitude climate with lower latitude climate. We also aim to link polar climate variability and predictions to potential ecologocal and socio-economic impacts and encourage submissions on this topic.
This session offers the possibility to present results from the ongoing projects and research efforts on the topic of high-latitude climate variability and prediction, including, but not limited to Year of Polar Prediction (YOPP), and the ARCPATH-project (Arctic Climate Predictions - Pathways to Resilient, Sustainable Societies).

Tipping elements in the Earth's climate system are continental-scale subsystems that are characterized by a threshold behavior. It has been suggested that these include biosphere components (e.g. the Amazon rainforest and coral reefs), cryosphere components (e.g. the Greenland and Antarctic ice sheets) and large-scale atmospheric and oceanic circulations (e.g. the thermohaline circulation, ENSO and Indian summer monsoon). Once operating near a threshold or tipping point, these components can transgress into a qualitatively different state by small external perturbations. The large-scale environmental consequences could impact the livelihoods of millions of people.

In this session, we aim to bring together experts presenting and discussing the state-of-the-art research on tipping elements in the Earth's climate system, both in empirical data and numerical modelling of past, present and future climate. Among other topics, issues to be addressed in this session include critical thresholds for specific tipping elements, typical time scales of tipping, interactions and feedbacks between tipping elements, the potential for tipping cascades as well as environmental and socio-economic impacts of tipping.

This session will focus on recent and upcoming advances in satellite remote sensing of the global cryosphere. We welcome presentations providing new insights into cryospheric processes in the broadest sense, ranging from ice sheets, glaciers, snow cover and snow properties, frozen soil and sea ice to extraterrestrial glaciology. While the advent of remote sensing has revolutionized the field of glaciology, a vast reservoir of potential remains to be unlocked by using these observations in concert with other data sets. We particularly encourage presentations discussing multi-platform data merging, integration of GIS and ground validation data, integration of remote sensing data into earth system models, as well as cloud computing and processing of super large data sets. We also encourage contributions focusing on historic satellite data re-analysis, novel processing approaches for upcoming satellite missions, and presentations outlining pathways to next-generation satellite missions for the coming decades.
We are committed to a well-balanced session.

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Invited Speaker is Christian Hauck (University of Fribourg) with the title:
'Geophysical monitoring techniques to observe Alpine permafrost degradation – a 20-years perspective'
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Geophysical measurements offer important baseline datasets as well as validation for modelling and remote sensing products for cryospheric sciences. Applications include the dynamics of ice-sheets, alpine glaciers and sea ice, changes in snow cover properties of seasonal and permanent snow, snow/ice-atmosphere-ocean interactions, permafrost degradation, geomorphic processes and changes in subsurface materials.

In this session we welcome contributions related to a wide spectrum of geophysical- and in-situ methods, including advances in diverse techniques such as radioglaciology, active and passive seismology, acoustic sounding, GPS/GNSS reflectometry or time delay techniques, cosmic ray neutron sensing, drone applications, geoelectrics and NMR. Contributions may concern field applications as well as new approaches in geophysical/in-situ survey techniques or theoretical advances in the field of data analysis, processing or inversion. Case studies from all parts of the cryosphere such as snow, alpine glaciers, ice sheets, glacial and periglacial environments and sea ice are highly welcome. The focus of the session is to compare experiences in the application, processing, analysis and interpretation of different geophysical and in-situ techniques in these highly complex environments.

This session is offered as a PICO: an engaging presentation format that has been successfully tested for this session during the last three years at EGU. All selected contributions will present their research orally, and then further present their research using interactive screens. This results in rich scientific feedback and is an effective tool for communicating science with high visibility.

Process understanding is key to assessing the sensitivity of glacier systems to changing climate. Comprehensive glacier monitoring provides the base for large-scale assessment of glacier change. Glaciers are monitored on different spatio-temporal scales, from extensive seasonal mass balance studies at selected glaciers to multi-decadal repeat inventories at the scale of entire mountain ranges. Internationally coordinated glacier monitoring aims at combining in-situ measurement with remotely sensed data, and local process understanding with global coverage. This session invites studies from a variety of disciplines, from tropical to polar glaciers, addressing both in-situ and remotely sensed monitoring of glaciers, as well as uncertainty assessments.
Keynotes:
Laura Thomson & David Burgess (Canada): The role and response of Canada's Arctic glaciers: Lessons learned from >50 years of mass balance observations
Bryn Hubbard (UK): 3D structure of Khumbu Glacier, Nepal, from borehole experiments.

A wide range of processes in the earth system directly affect geodetic observations. This session invites a wide array of contributions which showcase the use of geodesy for Earth science and climate applications, providing crucial insights into the state and change of the earth system and/or understanding its processes.

Data driven quantification of water mass fluxes through boundaries of Earth’s different regions and spheres provides important insights to other geoscience communities and informs model validation and improvement. Changes in regional sea level and ocean circulation are observed by altimetry and gravimetry. Natural and anthropogenic alterations of the terrestrial water cycle lead to changes in river runoff, precipitation, evapotranspiration, and water storage which may cause surface deformation sensed by GNSS stations and InSAR measurements as well as mass/gravity changes observed by satellite/ground gravimetry. Mass changes in the ice sheets and glaciers are detectable by both geometrical and gravimetric techniques. And other novel applications of geodetic techniques are emerging in many fields.

In addition, individual sensor recordings are often affected by high-frequency variability caused by, e.g., tides in the solid Earth, oceans, and atmosphere and their corresponding crustal deformations affecting station positions; non-tidal temperature and moisture variability in the troposphere modifying microwave signal dispersion; rapid changes in the terrestrially stored water caused by hydrometeorologic extreme events; as well as swift variations in relative sea-level that are driven by mass and energy exchange of the global oceans with other components of the Earth system, which all might lead to temporal aliasing in observational records. 

This session invites a wide array of contributions which showcase the use of geodesy for Earth science and climate applications. This session aims to cover innovative ways to use GRACE, GRACE-FO and other low Earth orbiters, GNSS techniques, InSAR, radar altimetry, and their combination with in-situ observations. We welcome approaches which tackle the problem of separating signals of different geophysical origin, by taking advantage of model output and/or advanced processing and estimation techniques. Since the use of geodetic techniques is not always straightforward, we encourage authors to think of creative ways to make their findings, data and software more readily accessible to other communities in hydrology, ocean, cryospheric, atmospheric and climate sciences. With author consent, highlights from the oral and poster session will be tweeted with a dedicated hashtag during the conference in order to increase the impact of the session.

Seismic techniques are becoming widely used to detect and quantitatively characterise a wide variety of natural processes occurring at the Earth’s surface. These processes include mass movements such as landslides, rock falls, debris flows and lahars; glacial phenomena such as icequakes, glacier calving/serac falls, glacier melt and supra- to sub-glacial hydrology; snow avalanches; water storage and water dynamics phenomena such as water table changes, river flow turbulence and fluvial sediment transport. Where other methods often provide limited spatial and temporal coverage, seismic observations allow recovering sequences of events with high temporal resolution and over large areas. These observational capabilities allow establishing connections with meteorological drivers, and give unprecedented insights on the underlying physics of the various Earth’s surface processes as well as on their interactions (chains of events). These capabilities are also of first interest for real time hazards monitoring and early warning purposes. In particular, seismic monitoring techniques can provide relevant information on the dynamics of flows and unstable slopes, and thus allow for the identification of precursory patterns of hazardous events and timely warning.

This session aims at bringing together scientists who use seismic methods to study Earth surface dynamics. We invite contributions from the field of geomorphology, cryospheric sciences, seismology, natural hazards, volcanology, soil system sciences and hydrology. Theoretical, field based and experimental approaches are highly welcome.

In the last 20 years, a major breakthrough in palaeo-environmental research has been the utilisation of 2D and 3D seismic reflection data and its integration with borehole petrophysics and core lithologies: the so-called “geological Hubble”. This step-change in seismic data quality and interpretive techniques has allowed imaging and analysis of the subsurface from the seafloor down to the Moho, and for palaeo-geographies and contemporary processes to be reconstructed across 1D (borehole) to 4D (repeat seismic) scales.

Though many Earth scientists know the basic principles of these subsurface datasets, they are often unaware of the full capability of seismic data paired with borehole data. We hope that this session will provide a window into the exciting and cross-disciplinary research currently being performed using geomorphological approaches, state-of-the-art seismic interpretation, and integrative methodologies.

Submissions are welcome from a range of geological settings, thus, exposing seismic interpreters and non-specialists to differing geological perspectives, the latest seismic workflows, and examples of effective seismic and borehole integration. Examples could include (but are not restricted to), glacigenic tunnel valley complexes, igneous intrusions, submarine landslides, channel and canyon systems, salt tectonics overburden expression, methane hydrates, and subsurface fluid flow, all under the theme of how seismic data are interpreted and how the results are applied (e.g. palaeo-environmental reconstruction, seafloor engineering, or carbon sequestration).

The submissions will highlight the rationale behind the interpretation of seismic geometries and will generate discussions around potential issues of equifinality (i.e. similar seismic geometries arising from different Earth processes). We thus invite submissions that aim to present new insights in seismic geomorphology and particularly welcome studies integrating borehole and geotechnical drilling information with shallow high-resolution seismic data and deeper traditional legacy oil industry data. Such studies are a crucial component in seismic inversion and refining or elucidating the accuracy of palaeo-geographies that are interpreted from just seismic data.

The session will be an excellent opportunity for subsurface geoscientists to showcase and discuss with contemporary geomorphologists and environmental scientists what can be achieved by utilising seismic and borehole data to unravel the Earth’s past.

Topographic data are fundamental to landscape characterization across the geosciences, for monitoring change and supporting process modelling. Over the last decade, the dominance of laser-based instruments for high resolution data collection has been challenged by advances in digital photogrammetry and computer vision, particularly in ‘structure from motion’ (SfM) algorithms, which offer a new paradigm to geoscientists.

High resolution topographic (HiRT) data are now obtained over spatial scales from millimetres to kilometres, and over durations of single events to lasting time series (e.g. from sub-second to decadal-duration time-lapse), allowing evaluation of dependencies between event magnitudes and frequencies. Such 4D-reconstruction capabilities enable new insight in diverse fields such as soil erosion, micro-topography reconstruction, volcanology, glaciology, landslide monitoring, and coastal and fluvial geomorphology. Furthermore, broad data integration from multiple sensors offers increasingly exciting opportunities.

This session will evaluate the advances in techniques to model topography and to study patterns of topographic change at multiple temporal and spatial scales. We invite contributions covering all aspects of HiRT reconstruction in the geosciences, and particularly those which transfer traditional expertise or demonstrate a significant advance enabled by novel datasets. We encourage contributions describing workflows that optimize data acquisition and post-processing to guarantee acceptable accuracies and to automate data application (e.g. geomorphic feature detection and tracking), and field-based experimental studies using novel multi-instrument and multi-scale methodologies. A major goal is to provide a cross-disciplinary exchange of experiences with modern technologies and data processing tools, to highlight their potentials, limitations and challenges in different environments.

Solicited speaker: Kuo-Jen Chang (National Taipei University of Technology) - UAS LiDAR data processing, quality assessment and geosciences prospects

An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot aboard. Originating mostly from military applications, their use is rapidly expanding to commercial, recreational, agricultural, and scientific applications. Unlike manned aircraft, UAVs were initially used for missions too "dull, dirty, or dangerous" for humans. Nowadays however, many modern scientific experiments have begun to use UAVs as a tool to collect different types of data. Their flexibility and relatively simple usability now allow scientist to accomplish tasks that previously required expensive equipment like piloted aircrafts, gas, or hot air balloons. Even the industry has begun to adapt and offer extensive options in UAV characteristics and capabilities. At this session, we would like people to share their experience in using UAVs for scientific research. We are interested to hear about specific scientific tasks accomplished or attempted, types of UAVs used, and instruments deployed.

This session aims at bringing together multidisciplinary studies that address the current state of Arctic observing systems, including strategies to improve them in the future. We invite contributions covering atmosphere, ocean, cryosphere and terrestrial spheres, or combinations thereof, by use of remote sensing, in situ observation technologies, and modeling. Particular foci are placed on (i) the analysis of strengths, weaknesses, gaps in spatial/temporal coverage, and missing monitoring parameters in existing observation networks and databases, and (ii) studies describing the development and/or deployment of new sensors or observation platforms that extend the existing observing infrastructure with multidisciplinary measurements. This session will be supported by the EU-H2020 project INTAROS, and welcomes contributions from other pan-Arctic networks (e.g. INTERACT, GTN-P, NEON, ICOS, SIOS, IASOA, AOOS), multi-disciplinary campaigns (e.g. ABoVE, NGEE Arctic, Arctic Ocean 2018, RV Polarstern cruises) or databases.

The availability of high spatial resolution Synthetic Aperture Radar (SAR) data, the advances in SAR processing techniques (e.g. interferometric, polarimetric, and tomographic processing), and the fusion of SAR with optical imagery as well as geophysical modelling allow ever increasing use of Imaging Geodesy using SAR/InSAR as a geodetic method of choice for earth system monitoring and investigating geohazard, geodynamic and engineering processes. In particular, the exploitation of data from new generation SAR missions such as Sentinel-1 that provide near real-time measurements of deformation and changes in land cover/use has improved significantly our capabilities to understand natural and anthropogenic hazards and then helped us mitigate their impacts. The development of high-resolution X-band SAR sensors aboard missions such as Italian COSMO-SkyMed (CSK) and German TerraSAR-X (TSX) has also opened new opportunities over the last decade for very high-resolution radar imaging from space with centimetre geometric accuracy for detailed analysis of a variety of processes in the areas of the biosphere, geosphere, cryosphere and hydrosphere. All scientists exploiting radar data from spaceborne, airborne and/or ground-based SAR sensors are cordially invited to contribute to this session. The main objective of the session is to present and discuss the progress, state-of-the-art and future perspectives in scientific exploitation of SAR data, mitigating atmospheric effects and error sources, cloud computing, machine learning and big data analysis, and interpretation methods of results obtained from SAR data for various types of disasters and engineering applications such as earthquakes, volcanoes, landslides and erosion, infrastructure instability and anthropogenic activities in urban areas. Contributions addressing scientific applications of SAR/InSAR data in biosphere, cryosphere, and hydrosphere are also welcome.

Snow avalanches range among the most prominent natural hazards which threaten mountain communities worldwide. This session is devoted to avalanche formation, forecasting and detection, and the dynamics of dense and powder snow avalanches and their accompanying transitional regimes. The first focus is on improving our understanding of avalanche formation processes and to foster the application to avalanche forecasting. We therefore welcome contributions from novel field, laboratory and numerical studies on topics including, but not limited to, the mechanical properties of snow, snow cover simulations, snow instability assessment, meteorological driving factors including drifting and blowing snow, spatial variability, avalanche release mechanics, remote avalanche detection and avalanche forecasting. The second focus is the interaction of snow avalanches with, and impact on, vulnerable elements, such as buildings, protection dams, forests, and roads. We welcome novel contributions from field, laboratory and numerical studies on topics including, but not limited to, avalanche dynamics and related processes, physical vulnerability of structures impacted by snow avalanches, avalanche hazard zoning and avalanche mitigation strategies. Furthermore, we solicit novel contributions from the field of granular flows, viscoplastic flows, density currents, turbulent flows, as well as contributions from other gravity flows communities, which can improve our understanding and modeling of snow avalanche propagation and their interaction with natural or man-made structures.

Understanding the evolution of firn is important for several reasons. Firstly, knowing the depth and the age of firn at pore close-off, and how these change through time, is essential for accurate interpretations of climate records from ice cores. Second, converting spaceborne measurements of volume change into mass change requires estimates of firn thickness and density changes through time. Finally, recent work has demonstrated the importance of meltwater retention in firn in buffering the Greenland and Antarctic ice sheets’ contribution to sea level. Although the spatial and temporal scales of these problems vary, they are united by a common need to understand the underlying physics of firn and its evolution.

We invite contributions on the subject of firn and firn evolution on all temporal and spatial scales. These may include: advances in measurements or observations of firn and firn processes at the microscale (e.g. microstructural studies) or macroscale (e.g. compaction measurements) and all types of firn modelling. We are particularly interested in assessments of uncertainty based on firn modelling and observations and work demonstrating important directions for future firn research.

Snow cover characteristics (e.g. spatial distribution, surface and internal physical properties) are continuously evolving over a wide range of scales due to meteorological conditions, such as precipitation, wind and radiation.
Most processes occurring in the snow cover depend on the vertical and horizontal distribution of its physical properties, which are primarily controlled by the microstructure of snow (e.g. density, specific surface area). In turn, snow metamorphism changes the microstructure, leading to feedback loops that affect the snow cover on coarser scales. This can have far-reaching implications for a wide range of applications, including snow hydrology, weather forecasting, climate modelling, and avalanche hazard forecasting or remote sensing of snow. The characterization of snow thus demands synergetic investigations of the hierarchy of processes across the scales ranging from explicit microstructure-based studies to sub-grid parameterizations for unresolved processes in large-scale phenomena (e.g. albedo, drifting snow).

This session is therefore devoted to modelling and measuring snow processes across scales. The aim is to gather researchers from various disciplines to share their expertise on snow processes in seasonal and perennial snowpacks. We invite contributions ranging from “small” scales, as encountered in microstructure studies, over “intermediate” scales typically relevant for 1D snowpack models, up to “coarse” scales, that typically emerge for spatially distributed modelling over mountainous or polar snow- and ice-covered terrain. Specifically, we welcome contributions reporting results from field, laboratory and numerical studies of the physical and chemical evolution of snowpacks, statistical or dynamic downscaling methods of atmospheric driving data, assimilation of in-situ and remotely sensed observations, representation of sub-grid processes in coarse-scale models, and evaluation of model performance and associated uncertainties.

This session is linked closely to the session HS2.1.2/CR3.11. While the focus of our session is on monitoring and modelling snow processes across scales, session HS2.1.2/CR3.11 addresses monitoring and modelling of snow for hydrologic applications.

All components of the cryosphere are strongly impacted by climate change and have been undergoing significant changes over the past decades. Most visibly, glaciers are shrinking and thinning. Snow cover and duration is reduced, and permafrost, in both Arctic and alpine environments, is thawing. Changes in sea ice cover and characteristics have attracted widespread attention, and changes in ice sheets are monitored with care and concern.
Risks associated with one or several of these cryosphere components have been present throughout history. However, as well documented atmospheric warming continues, we expect changes in the magnitude and frequency of hazards with profound implications for risks. New or growing glacier lakes pose a threat to downstream communities through the potential for sudden drainage. Thawing permafrost can destabilize mountain flanks, and eventually result in destructive rock and ice avalanches. An accelerated rate of permafrost degradation in low-land areas poses risk to existing and planned infrastructure and raises concerns about large-scale emission of greenhouse gases currently trapped in Arctic permafrost. Decreased summertime sea ice extent may produce both risks and opportunities in terms of large-scale climate feedbacks and alterations, coastal vulnerability, and new access to transport routes and natural resources. Eventually, rapid acceleration of outlet glacier ice discharge and collapse of ice sheets is of major concern for sea level change.
This session invites contributions across all cryosphere components that addresses risks associated with observed or projected physical processes. Contributions considering more than one cryosphere component (e.g. glaciers and permafrost) are particularly encouraged. Contributions can consider hazards and risks related to changes in the past, present or future. Discussion of both new risks and opportunities are encouraged, as long as an evidence based, critical analysis is provided.

Clouds play an important role in the polar climate due to their interaction with atmospheric radiation and their role in the hydrological cycle linking poleward water vapour transport with precipitation, thereby affecting the mass balance of the polar ice sheets. Cloud-radiative feedbacks have also an important influence on sea ice. Cloud and precipitation properties depend strongly on the atmospheric dynamics and moisture sources and transport, as well as on aerosol particles, which can act as cloud condensation and ice nuclei.

This session aims at bringing together researchers using observational (in-situ, aircraft, ground-based, and satellite-based remote sensing) and/or modeling approaches (at various scales) to improve our understanding of polar tropospheric clouds, precipitation, and related mechanisms and impacts. Contributions are invited on various relevant processes including (but not limited to):
- Drivers of cloud/precipitation microphysics at high latitudes,
- Sources of cloud nuclei both at local and long range,
- Linkages of polar clouds/precipitation to the moisture sources and transport,
- Relationship of the poleward moisture transport to processes in the tropics and extra-tropics, including extreme transport events (e.g., atmospheric rivers, moisture intrusions),
- Relationship of moisture/cloud/precipitation processes to the atmospheric dynamics, ranging from synoptic and meso-scale processes to teleconnections and climate indices,
- Role of the surface-atmosphere interaction in terms of mass, energy, and cloud nuclei particles (evaporation, precipitation, albedo changes, cloud nuclei sources, etc)
- Effects that the clouds/precipitation in the Polar Regions have on the polar and global climate system, surface mass and energy balance, sea ice and ecosystems.

Papers including new methodologies specific to polar regions are encouraged, such as (i) improving polar cloud/precipitation parameterizations in atmospheric models, moisture transport events detection and attribution methods specifically in the high latitudes, and (ii) advancing observations of polar clouds and precipitation. We would like to emphasize collaborative observational and modeling activities, such as the Year of Polar Prediction (YOPP), Polar-CORDEX, the (AC)³ project on Arctic Amplification, SOCRATES and other campaigns over the Southern Ocean/Antarctica, and encourage related contributions.

The session is endorsed by the SCAR Antarctic Clouds and Aerosols Action Group.

Young scientist/student presentations are especially encouraged and we will reserve several oral units for such papers in this session.

The atmospheric water cycle is a key component of the climate system,
and links across many scientific disciplines. Processes and dynamics at
different scales interact throughout the atmospheric life cycle of
water vapour from evaporation to precipitation. This session sets the
focus on processes, dynamics and characteristics at the evaporation
sources, during moisture transport, and at the precipitation sinks as
observed from in-situ and remote sensing, recorded by (paleo)climate
archives, and as simulated for past, present and future climates.

We invite studies

* focusing on extensive transient features of the atmospheric water
cycle, such as Atmospheric Rivers, Cold-Air Outbreaks, warm conveyor
belts, tropical moisture exports, precipitation extremes, and the
monsoon systems.

* investigating the large-scale drivers of the water cycle features’
variability and change by looking at observations, reanalyses or
global/regional climate simulations, in order to improve their
predictability

* involving and connecting results from field campaigns (YOPP, MOZAIC,
NAWDEX), reanalysis data, indicators of past hydroclimate from climate
proxies such as ice cores and stalagmites, and model predictions of the
future evolution of the atmospheric water cycle,

* applying methods such as stable isotopes as physical tracers in the
water cycle, tagged water tracers, and Lagrangian moisture source
diagnostics to identify source-sink relationships and to evaluate model
simulations of the water cycle,

* describing the global and regional state of the atmospheric cycle
with characteristics such as the recycling ratio, life time of water
vapour, and moisture transport distance

We particularly encourage contributions to link across neighbouring
disciplines, such as atmospheric science, climate, paleoclimate,
cryosphere, and hydrology.

Atmosphere and Cryosphere are closely linked and need to be investigated as an interdisciplinary subject. Most of the cryospheric areas have undergone severe changes in last decades while such areas have been more fragile and less adaptable to global climate changes. This AS-CR session invites model- and observational-based investigations on any aspects of linkages between atmospheric processes and snow and ice on local, regional and global scales. Emphasis is given on the Arctic, high latitudes and altitudes, mountains, sea ice, Antarctic regions. In particular, we encourage studies that address aerosols (such as Black Carbon, Organic Carbon, dust, volcanic ash, diatoms, bioaerosols, bacteria, etc.) and changes in the cryosphere, e.g., effects on snow/ice melt and albedo. The session also focus on dust transport, aeolian deposition, and volcanic dust, including health, environmental or climate impacts at high latitudes, high altitudes and cold Polar Regions. We emphasize contributions on biological and ecological sciences including dust-organisms interactions, cryoconites, bio-albedo, eco-physiological, biogeochemical and genomic studies. Related topics are light absorbing impurities, cold deserts, dust storms, long-range transport, glaciers darkening, polar ecology, and more. The scientific understanding of the AS-CR interaction needs to be addressed better and linked to the global climate predictions scenarios.

The polar climate system is strongly affected by interactions between the atmosphere and the cryosphere. Feedback mechanisms between snow, land ice, sea ice and the atmosphere, such as blowing snow, ice melt, polynya formation, and sea ice production play an important role. Atmosphere-ice interactions are also triggered by synoptic weather phenomena such as cold air outbreaks, katabatic winds, polar lows, atmospheric rivers, Foehn winds and heatwaves. However, our understanding of these processes is still incomplete, and to fully capture how atmosphere, land ice and sea ice are coupled on different spatial and temporal scales, remains a major challenge.
This session will provide a setting to foster discussion on the atmosphere-ice coupling in both the Northern and Southern Hemispheres. It will offer the opportunity to review newly acquired knowledge, identify gaps, and which instruments, tools, and studies can be designed to address these open questions.
We invite contributions on all observational and modelling aspects of Arctic and Antarctic meteorology and climatology that address atmospheric interactions with the cryosphere. This may include studies of atmospheric dynamics that influence sea-ice dynamics or ice-sheet mass balance, or investigations into the variability of the atmospheric circulation such as polar jets, the circumpolar trough, storm tracks and their link to changes in the cryosphere.

Changes in the Arctic and Antarctic climate systems are strongly related to processes in the boundary layer and their feedbacks with the free troposphere. An adequate understanding and quantification of these processes is necessary to improve predictions of future changes in the polar regions and their teleconnections with mid-latitude weather and climate, including meridional transport of heat, moisture and air pollutants. Processes include atmosphere-ocean-ice (AOI) interactions, such as physical and chemical snow processes (e.g. snow photochemistry), exchange of chemical constituents, sources of aerosol, polynya formation processes, sea ice production and bottom water formation, and cloud formation, which represent key processes for the atmosphere, ocean and the cryosphere. AOI interactions are also triggered by and have feedbacks with synoptic systems and mesoscale weather phenomena such as cold air outbreaks, katabatic winds and polar lows. Associated processes also include the effect of warm air advection and clouds on the surface energy budget and related boundary layer exchanges. Of increasing interest is the study of extremes such as heat waves and storms, but also extreme meridional transport events that can disturb the physical and chemical state of the high latitudes and may have a large impact on ecosystem changes. In addition, Arctic boundary-layer processes play an important role for local Arctic air pollution and for the health and ecosystem impacts thereof. In addition, understanding natural processes including AOI interactions is essential to understand of the background atmosphere to quantify the anthropogenic impacts. Shallow inversions, mostly during winter-time, lead to high air pollutant concentrations. Even though severe air pollution episodes are frequently observed in the Arctic, knowledge on urban emission sources and atmospheric chemical processing of pollution, especially under cold and dark conditions, are poorly understood.

This session is intended to provide an interdisciplinary forum to bring together researchers working in the area of boundary layer processes and high-latitude weather and climate (including snow physics, air/snow chemistry, and oceanography). Cryosphere and atmospheric chemistry processes (the focus of the IGAC/SOLAS activity “CATCH” and the IGAC/IASC activity “PACES”) are highly relevant to this session. We invite contributions e.g. in the following areas:

1. Observations and research on the energy balance, physical and chemical exchange processes, and atmosphere-ocean-ice (AOI) interactions including particle sources.
2. Results from high-elevation sites where similar processes occur over snow and ice.
3. Field programs, laboratory studies and observational studies (including remote sensing).
4. Model studies and reanalyses.
5. Advances in observing technology.
6. External controls on the boundary layer such as clouds, aerosols, radiation.
7. Teleconnections between the polar regions and mid-latitudes resulting in effects related to atmosphere-ice-ocean interactions as well as insights provided by monitoring of water vapor isotopes that shed light on air mass origins.
8. High-latitude urban air quality studies.

By accumulating precipitation at high elevations, snow and ice completely change the hydrologic response of a watershed. Water stored in the snow pack and in glaciers thus represents an important component of the hydrological budget in many regions of the world and a sustainment to life during dry seasons. Predicted impacts of climate change in headwater catchments (including a shift from snow to rain, earlier snowmelt, and a decrease in peak snow accumulation) will affect both water resources distribution and water uses at multiple scales, with potential implications for energy and food production.
Our knowledge about snow/ice accumulation and melt patterns is highly uncertain, because of both limited availability and inherently large spatial variability of hydrological and weather data in remote areas at high elevations. This translates into limited process understanding, especially in a warming climate. The objective of this session is to integrate specialists focusing on snow accumulation and melt within the context of catchment hydrology and snow as a source for glacier ice and melt, hence streamflow. The aim is to integrate and share knowledge and experiences about experimental research, remote sensing and modelling.

Specifically, contributions addressing the following topics are welcome:
- results of experimental research on snowmelt runoff processes and their potential implementation in hydrological models;
- development of novel strategies for snowmelt runoff modelling in various (or changing) climatic and land-cover conditions
- evaluation of observed in-situ or remote-sensing snow products (e.g. snow cover, albedo, snow depth, snow water equivalent) and their application for snowmelt runoff calibration, data assimilation or operational streamflow forecasting
- observational and modelling studies that shed new light on hydrological processes in glacier-covered catchments, e.g., impacts of glacier retreat on water resources and water storage dynamic or the application of techniques for tracing water flow paths.
Studies on cryosphere-influenced mountain hydrology, such as landforms at high elevation and their relationship with streamflow, water balance of snow/ice-dominated, high mountain regions, etc.
This session is linked closely to the session CR3.04/AS4.6/CL2.15/HS2.1.3 . While the focus of our session is on the monitoring and modelling of snow for hydrologic applications, session CR3.04/AS4.6/CL2.15/HS2.1.3 addresses monitoring and modelling of snow processes across scales.

Grain size or grain size distributions (GSDs) play a major role in many fields of geoscience research. Paleopiezometry is based on the relation between grains size and flow stress. Environments of depositions have typical GSDs. Time temperature and grain size have characteristic relations during static grain growth. Fracture processes are associated with the fractal dimension of the GSD they produce, etc.. In all these cases, meaningful interpretations rest on the correct acquisition and quantification of grain size data.

The aim of this short course is to discuss with participants the following questions

1) when do we need grain size analysis ? what is it good for ? what are the limitations ?
2) how do we identify grains? what are the criteria for segmentation?
3) how do we define reliable measures for grain size ?
4) what do we mean by 'mean grain size' ?
5) how much data do we need ?
6) and what about errors ?

Handouts will be available in electronic form.

Please send email if you want to participate (renee.heilbronner@unibas.ch)

The Permafrost Open Session is a platform for the presentation and discussion of current research focusing on (a) permafrost and associated natural systems; (b) the interaction of permafrost and climate; (c) the impact of permafrost changes on both, natural and human systems; and (d) the measurement, understanding, modeling, and parameterization of corresponding processes. Contributions are welcome on high-latitude, mountain, and planetary permafrost.

We look forward to a high-quality session with a high number of contributions that reflect diverse scientific fields, approaches, and geographic locations. We would like to especially encourage contributions that (a) present novel measurement and monitoring approaches; (b) present new strategies to improve process understanding; (c) come from or interface with differing fields of science or innovative technologies and methods; (d) investigate model validation, model uncertainty, or spatial and temporal scale/scalability; (e) couple models of diverse processes or scales.

The Permafrost Open Session complements several other sessions with more specific foci (such as natural hazards, geophysics, or geomorphology) and is intended to be the forum for research primarily focusing on permafrost phenomena.

Present-day glacial and periglacial processes in cold regions, i.e. arctic and alpine environments, provide modern analogues to processes and climatic changes that took place during the Pleistocene, including gradual retreat or collapse of ice sheets and mountain glaciers, and melting and shrinking of low-land permafrost. Current changes in mid-latitude mountain ranges could also serve as a proxy for future changes in arctic regions within a context of climate change (e.g. speed-up of creeping permafrost features, relictification of rock glaciers).

We invite contributions that either:
1. investigate present-day glacial and/or periglacial landforms, sediments and processes to describe the current state, to reconstruct past environmental conditions and to predict future scenarios in cold regions; or
2. have a Quaternary focus and aim at enhancing our understanding of past glacial, periglacial and paraglacial processes, also through the application of dating techniques.

Case studies that use a multi-disciplinary approach (e.g. field, laboratory and modelling techniques) and/or that highlight the interaction between the glacial, periglacial and paraglacial cryospheric components in cold regions are particularly welcome.

Keynote lecture:
Hanne Hvidtfeldt Christiansen (Svalbard): Permafrost thermal dynamics in periglacial landforms in Svalbard during the last decade
Martin Margold (Prague): The retreat chronology of the western Laurentide Ice Sheet

Mountain glaciations provide an invaluable record for past and present climate change. They are vital for any palaeoclimatologic interpretation and many related research questions. The utilization of this potential is, however, not trivial because of the wide diversity of formerly and currently glaciated mountain ranges. Apart from their specific complex and interacting geomorphological process-systems different climatic and glaciological conditions cause any subsequent global or intra-hemispheric correlations to become incredible challenging. This problem is further enhanced by ongoing specialisation within the scientific community. Working groups primarily focusing on either individual aspects of related research or selected mountain regions often remain somewhat disconnected. As a consequence of the challenges imposed on mountain glaciations, they occasionally seem to become sidelined in the context of Quaternary environmental reconstructions in comparison with other formerly glaciated regions. This discrepancy constitutes an unfortunate and unsatisfactory consequence that should be conquered.

The primary aim of this session is to evaluate the potential of mountain glaciations records and stimulate further research in this important field of research. Contributions on all relevant aspects of the topic are welcomed, for example: (a) glacial landforms and reconstruction of past glaciers, (b) dating techniques and geochronology compilations, (c) glacier dynamics and palaeoclimatic interpretations, or (d) impacts of ecosystems and human evolution/society. Submissions targeting these connections are specifically encouraged. While we encourage submitting abstracts from all abovementioned topics within the broad field of mountain glaciations, we would like to invite in particular those highlighting the specific conditions of mountain glaciations or addressing the relationship and connections between different of their aspects. To address the diversity of mountain glaciations, contributions from high-, middle-, and low-latitude mountain ranges as well as from continental to maritime regions are all welcomed. The time scale of the session will cover the whole time range from Early Pleistocene glaciations to the LGM and Holocene/modern glaciers.

During the past years, precursors of this session have steadily become more popular and attracted contributions from a wide range of research topics and study areas, both with a high diversity of methodological approaches. Their common target was to allow a better understanding of how glacial landforms should be interpreted in a (palaeo)climatic and/or chronological context. The session ultimately aims to facilitate a closer connection between different topological, methodological, and regional working groups related to various aspects of mountain glaciations in space and time. It is further designed to give everyone interested in the emerging collaborative research network “The Legacy of Mountain Glaciations” an opportunity to meet and exchange ideas and expertise.

We are pleased that Benjamin Chandler has accepted our invitation and will present a solicited talk about "Mapping the legacy of mountain glaciations".

Please note that the session conveners organized a public splinter meeting on Tuesday (April 9th) between 12.45 and 13.45 in room 0.51 (SMP 6) to meet all colleagues involved with the new application for a COST Action “Legacy of Mountain Glaciations” and those interested in the topic, We will use the opportunity to make this initiative more public and to discuss possible future directions.

Geochronological frameworks are essential for the study of landscape evolution. Over the last decades, geochronological techniques such as cosmogenic nuclides, thermochronology, radiocarbon and luminescence dating have improved in accuracy, precision, and temporal range. Recently, the development of new approaches, new isotopic/mineral systems, and the increasing combination of these techniques are expanding their range of applications. This session explores these advances and novel applications, which include the study of erosional rates and processes, sediment provenance, burial and transport times, bedrock exposure or cooling histories, landscape dynamics, and the examination of potential biases and discordances in geochronological data. We welcome contributions that use dating tools which are established or in development, particularly those that quantify geomorphological processes with novel approaches and/or generic implications. We encourage studies that combine different techniques (e.g. CRN, luminescence, thermochronology, etc.) or data sets (e.g. field, remote sensing, numerical modelling), and/or highlight the latest developments and open questions in the application of geochronometers to landscape evolution questions.

Invited speakers: Prof. Kristina Hippe and Prof. Todd Ehlers.

Mountain environments host highly dynamical and widespread erosion, sedimentation, and weathering processes. These processes cover a wide range of temporal and spatial scales, from glacial & periglacial erosion, mechanical & chemical weathering, rock fall, debris flows, landslides, to river aggradation & incision. These processes react to a wide spectrum of external and internal forcings, including permafrost retreat, strong precipitation events, climate change, earthquakes or sudden internal failure. Measuring the dynamical interplay of erosion, sedimentation as well as quantifying their rates and fluxes is an important part of source to sink research but it is highly challenging and often limited by difficult terrain. Furthermore, these dynamical processes can threaten important mountain infrastructures and need to be understood and quantified for a better societal and engineering preparation to the natural hazards they pose.

We welcome contributions investigating:
- sediment mobilization and deposition
- links between erosion, weathering, and the carbon cycle
- concepts of dynamics and connectivity of sediments and solutes
- quantification of erosion, sedimentation, and weathering fluxes in space and time
- sediment travel times and transport processes
- interaction of stabilizing and destabilizing processes on the slopes
We invite presentations that focus on conceptual, methodological, or modelling approaches or a combination of those in mountain environments and particularly encourage early career scientists to apply for this 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.

Understanding the impacts of climate change on ice sheets and glaciers requires accurate surface mass balance. The interaction of ice sheets and glaciers with the atmosphere means that coupled atmosphere-ocean modes and large-scale weather patterns, meso-scale circulations over mountains, and local-scale energy and mass exchanges in the near-surface boundary layer can control the surface mass balance. Surface processes including melt-albedo feedbacks and firn densification introduce further complexity in determining surface mass balance. The Ice Sheets Model Intercomparison Project (ISMIP6), part of the Climate Model Intercomparison Project (CMIP6), aims to constrain the total mass balance contribution of ice sheets and glaciers to sea level rise. In this context, accurate estimates of surface mass balance from both models and observations are crucial, and so intercomparisons of models are currently underway.

This session focuses on (i) novel field- and remotely-sensed advances in measuring the surface energy balance and surface mass balance and (ii) process-based modelling that improves our understanding of glacier and ice sheet surface mass balance and atmospheric interaction. We invite contributions from a broad range of theoretical, numerical or observational studies that explore historic, recent and projected changes to glacier and ice sheet surface mass balance and atmospheric interaction. The range of topics includes but is not limited to: surface energy balance; improvements to satellite SMB retrievals; firn densification; future atmospheric circulation impacts; changes in cloudiness; and the impact of impurities upon albedo. We particularly welcome contributions which focus on improvements to process understanding that will lead to better SMB estimates in the future.

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.

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.

The half-century since the first deep ice core drilling at Camp Century, Greenland, has seen extensive innovation in methods of ice sample extraction, analysis and interpretation. Ice core sciences include isotopic diffusion analysis, multiple-isotope systematics, trace gases and their isotopic compositions, ice structure and physical properties, high-resolution analysis of major and trace impurities, and studies of DNA and radiochemistry in ice, among many others. Many climate and geochemical proxies have been identified from ice cores, with ongoing effort to extend their application and refine their interpretation. Great challenges remain in the field of ice coring sciences, including the identification of suitable sites for recovery of million-year-old ice; spatial integration of climate records (e.g. PAGES groups Antarctica2k and Iso2k); and deeper understanding of glaciological phenomena such as streaming flow, folding of layers and basal ice properties. This session welcomes all contributions reporting the state-of-the-art in ice coring sciences, including drilling and processing, dating, analytical techniques, results and interpretations of ice core records from polar ice sheets and mid- and low-latitude glaciers, remote and autonomous methods of surveying ice stratigraphy, and related modelling research.

In recent decades, quantitative methods have become increasingly important in the field of palaeoenvironmental, palaeoclimatic and palaeohydrological reconstruction, due to the need for comparison between different records and to provide boundary conditions for computational modelling. Continental environmental archives (e.g. speleothems, lakes, land snails, rivers, or peatlands) are often highly temporally resolved (subdecadal to seasonal) and may provide more direct information about atmospheric and hydrological processes than marine archives. The wide variety of archive types available on land also allows for intercomparison and ground-truthing of results from different techniques and different proxies, and multi-proxy reconstructions from the same archive can disentangle local and supra-regional environmental conditions. This approach is particularly useful for the reconstruction of hydrological dynamics, which are challenging to reconstruct due to their high spatial variability, signal buffering, nonlinearities and uncertainties in the response of available paleoclimate archives and proxies. For example, climate-independent factors such as land cover change can affect the local to regional water availability recorded in proxies.

This session aims to highlight recent advances in the use of innovative and quantitative proxies to reconstruct past environmental change on land. We present studies of various continental archives, including but not limited to carbonates (caves, paleosols, snails), sediments (lakes, rivers, alluvial fans), and biological proxies (tree rings, fossil assemblages, plant biomarkers). We particularly include studies involving the calibration of physical and chemical proxies that incorporate modern transfer functions, forward modeling and/or geochemical modeling to predict proxy signals, and quantitative estimates of past temperature and palaeohydrological dynamics. We also include reconstructions of temperature and hydrologic variability over large spatial scales and paleoclimate data assimilation. This session will provide a forum for discussing recent innovations and future directions in the development of terrestrial palaeoenvironmental proxies on seasonal to multi-millennial timescales.

This session aims to highlight recent advances in the use of innovative and quantitative proxies to reconstruct past environmental change on land. We welcome studies of any continental archive, including but not limited to carbonates (caves, paleosols, snails), sediments (lakes, rivers, alluvial fans), ice, and biological proxies (tree rings, fossil assemblages, plant biomarkers). We particularly encourage studies involving the calibration of physical and chemical proxies that incorporate modern transfer functions, forward modeling and/or geochemical modeling to predict proxy signals, and quantitative estimates of past temperature and precipitation amounts. We also welcome reconstructions of temperature and hydrologic variability over large spatial scales, including paleoclimate data assimilation studies. This session will provide a forum for discussing recent innovations and future directions in the development of terrestrial palaeoenvironmental proxies on seasonal to multi-millennial timescales.

Glaciers and volcanoes interact in a number of ways, including instances where volcanic/geothermal activity alters glacier dynamics or mass balance, via subglacial eruptions or the deposition of supraglacial tephra. Glaciers can also impact volcanism, for example by directly influencing mechanisms of individual eruptions resulting in the construction of distinct edifices. Glaciers may also influence patterns of eruptive activity when mass balance changes adjust the load on volcanic systems. However, because of the remoteness of many glacio-volcanic environments, these interactions remain poorly understood.
In these complex settings, hazards associated with glacier-volcano interaction can vary from lava flows to volcanic ash, lahars, pyroclastic flows or glacial outburst floods. These can happen consecutively or simultaneously and affect not only the earth, but also glaciers, rivers and the atmosphere. As accumulating, melting, ripping or drifting glaciers generate signals as well as degassing, inflating/ deflating or erupting volcanoes, the challenge is to study, understand and ultimately discriminate these potentially coexisting signals. We wish to fully include geophysical observations of current and recent events with geological observations and interpretations of deposits of past events.
We invite contributions that deal with the mitigation of the hazards associated with ice-covered volcanoes, that improve the understanding of signals generated by ice-covered volcanoes, or studies focused on volcanic impacts on glaciers and vice versa. Research on recent activity is especially welcomed. This includes geological observations e.g. of deposits in the field or remote-sensing data, together with experimental and modelling approaches. We also invite contributions on past activity and glaciovolcanic deposits. We aim to bring together scientists from volcanology, glaciology, seismology, geodesy, hydrology, geomorphology and atmospheric science in order to enable a broad discussion and interaction.

The rapid decline of Arctic sea ice in the last decade is a dramatic indicator of climate change.  The last 12 years have seen lower Arctic summer sea ice extents than in the previous 29 years of satellite records. The Arctic sea ice cover is now thinner, weaker and drifts faster. The ocean is also changing, the volume of freshwater stored in the Arctic and has increased as have the inputs of coastal runoff from Siberia and Greenland. Concurrently inflows from the Atlantic and Pacific Oceans have warmed. As the global surface temperature rises, the Arctic Ocean is speculated to become seasonally ice-free in the 21st century, which prompts us to revisit our perceptions of the Arctic system as a whole. What could the Arctic look like in the future? How are the present changes in the Arctic going to affect the lower latitudes? What aspects of the changing Arctic should future observations and modelling programs address? The scientific community is investing considerable effort in organising our current knowledge of the physical and biogeochemical properties of the Arctic, exploring poorly understood coupled atmosphere-sea-ice-ocean processes to improve prediction of future changes in the Arctic.
 
In this session, we invite contributions on a variety of aspects of past, present and future climates of the Arctic. We encourage submissions addressing interaction between ocean, atmosphere and sea ice and on studies linking changes in the Arctic to the global ocean. Submissions with a focus on emerging cryospheric, oceanic and biogeochemical processes and their implications are particularly welcome. The session promotes results from current Arctic programmes and discussions on future plans for Arctic Ocean modelling and measurement strategies. This session is cosponsored by the CLIVAR /CliC Northern Ocean Regional Panel (NORP) that aims to facilitate progress and identify scientific opportunities in (sub)Arctic ocean-sea-ice-atmosphere research.

Snow and ice can capture and store contaminants both local and global in origin. The decrease in glacier cover, snow cover and sea ice in response to climate affects cycling of airborne impurities in polar and alpine environments, accelerating and enhancing their release. In this context snow and ice act as a secondary source for numerous organic and inorganic atmospheric contaminants that were deposited on their surface during recent decades, including persistent organic pollutants, radioactive species, microplastics, pesticides, and heavy metals. The release of contaminants from snow and ice to glacier forefields, rivers and seas might pose a hazard to these ecosystems and to human health, particularly under accelerated melt conditions.

Identification and assessment of this hazard relies, for each contaminant class, on the understanding of processes that control their accumulation, release and downstream transport. The physical and chemical forms in which contaminants are removed from the atmosphere and hydrosphere may further affect their interactions with mineral substances and biota. Existing studies suggest that the contaminant release process is not linear, and that interactions between meltwater, supraglacial debris and glacial microbiology may be crucial in the accumulation and transport of contaminants in glacier catchments. For example, evidence is mounting that cryoconite can efficiently accumulate radionuclides from anthropogenic sources to potentially hazardous levels in glaciers around the world. At the same time, the high biological activity present in cryoconite could enhance the degradation of organic pollutants, with important implications for remediation. A portion of contaminants released from glaciers may also be stored in their proglacial zones as shown by the very high concentrations of radionuclides found by several recent studies. The effects of contaminant transport on the pro-glacial environment and downstream communities remain uncertain, but improved understanding of the impacts of contaminants in land ice, sea ice, and snow is clearly warranted.

The session aims to contribute to the development of this emerging and interdisciplinary field, welcoming presentations from across cryospheric, hydrological, and biogeochemical sciences, and other research areas.

Publishing your research in a peer reviewed journal is essential for a career in research, however, getting those first few papers submitted can be daunting. This short course, given by the co editor-in-chief of The Cryosphere Thomas Mölg, will cover all you need to know about the publication process from start to end. This includes: what the editor looks for in your submitted paper, how to deal with corrections or rejections, and how best to communicate with your reviewers and editors for a smooth transition from submission to publication. There will also be time for questions from the audience, and for the editor to give you some ‘top tips’ for a successful publication. This course is aimed at early-career researchers who are about to step into the publication process, and those who have a few papers under their belt, but may not have published in The Cryosphere previously. Similarly, this course will be of interest to those looking to get involved in the peer-review process through reviewing and editing.

This year marks the 250th anniversary of the birth of Alexander von Humboldt (1769-1859), the intrepid explorer of the Andes and other regions in the world, and the most famous scientist of his time. Alexander von Humboldt is perhaps best known for his radical new vision of nature as a complex and interconnected global force, thereby becoming the founder of the field of biogeography and laying the ground for modern Earth-System Science approaches. It seems fitting to pay tribute to Alexander von Humboldt’s legacy by reviewing the state of the art in studies of the coupled lithosphere – atmosphere – hydrosphere – biosphere system with a focus on the Andean mountain belt. The Andes have become one of the main natural laboratories in the world to explore these questions and many recent studies have addressed its tectonic and geodynamic evolution, but also the two-way couplings between surface uplift, climatic evolution and biodiversity in the Andes and its foreland. This Union Session will bring together world-leading specialists on these questions with the aim to shed light on both suspected and unexpected couplings in the system.

Over the whole Earth history, the climate has encountered tipping points, shifting from one regulated system to the other. This tilting motion affects both climate and the carbon cycle and has played a major role in the evolution of the Earth climate, at all timescales. Earth History has been ponctuated by large climate changes and carbon cycle reorganizations, from large climate variations occurring in deep times (snowball events, terrestrialisation, Mesozoic and early Cenozoic warm episodes, quaternary glacial cycles…) to past and on-going abrupt events. Many potential triggers of those climate and carbon cycle shifts have been proposed and tested through modeling studies, and against field data, such as those directly or indirectly linked with tectonics (plate motion, orogenesis, opening/closing of seaways, weathering…) and orbital forcing. Given that the Earth climate is currently experiencing an unprecedented transition under anthropogenic pressure, understanding the mechanisms behind the scene is crucial.

Our aim is to point out the most recent results concerning how a complex system as the climate of the Earth has undergone many tipping points and what is the specificity of the future climate changes. Therefore, within this session, we would like to encourage talks discussing advances in our record and modeling of the forces triggering and amplifying the changes of Earth climate and carbon cycle across spatial and temporal scales.

In today’s changing world we need to tap the potential of every talented mind to develop solutions for a sustainable future. The existence of under-representation of different groups (cultural, national and gender) remains a reality across the fields of science, technology, engineering, and mathematics (STEM fields) around the world, including the geosciences. This Union Symposium will focus on remaining obstacles that contribute to these imbalances, with the goal of identifying best practices and innovative ideas to overcome obstacles.

EGU is welcoming six high-level speakers from the funding agencies and research centres on both sides of the Atlantic related to geosciences to present efforts and discuss initiatives to tackle both implicit and explicit biases. Speakers are:

Jill Karsten, AGU Diversity and Inclusion Task Force (confirmed)
Erika Marín-Spiotta, University of Wisconsin - Madison (confirmed)
Daniel Conley, Lund University (confirmed)
Giulio di Toro, University of Padua (confirmed)
Liviu Matenco, Utrecht University (confirmed)
Barbara Romanowicz, European Research Council (confirmed)

Atmospheric composition matters to climate, weather forecasting, human health, terrestrial and aquatic ecosystems, agricultural productivity, aeronautical operations, renewable energy production, and more. Hence research in atmospheric composition is becoming increasingly cross-cutting and linked to many disciplines including climate, biogeosciences, hydrology, natural hazards, computer and data sciences, socio-economic studies and many others. There is a growing need for atmospheric composition information and an improved understanding of the processes that drive changes in the composition and resulting impacts. While atmospheric composition research is advancing rapidly, there is a need to pay more attention to the translation of this research to support societal needs. Although translational research is a major focus of the health sciences and meteorology, it is in a relatively early stage in atmospheric composition. In this Union Symposium, we plan to highlight the need for, and to illustrate exciting advances in the translation of atmospheric composition research to support services. We will build upon work within the World Meteorological Organization and other communities related to the closer linkages of weather, atmospheric composition, and climate research and related services. We will also articulate the needs for advances in observing systems, models and a better understanding of fundamental processes. This session will also serve as a celebration of the 30 year anniversary of the WMO Global Atmosphere Watch programme and an opportunity for the broader community to envision partnerships needed to facilitate the effective translation of atmospheric composition research.

In October 2018, the IPCC published its special report on impacts of global warming of 1.5 deg C. Another recent, highly publicised study suggests that the planet could pass an irreversible threshold into a so called “Hothouse Earth” state for a temperature increase of as low as 2 degrees C above pre-industrial temperatures, while other studies and commentaries have emphasised the urgency on climate action, arguing that 2020 must be a turning point for global fossil fuel emissions, to increase the chance of maintaining a safe operating space for the humans on the planet. In 2018, the IPCC celebrated its 30th anniversary. The importance of taking action on human-induced climate change has been emphasised with governments around the world since the 1990s yet CO2 concentrations continue to rise and international initiatives have, to date, had limited and insufficient impact to avert some of the most serious consequences of climate change.
How close are we to one or more critical thresholds (cliff edge)? Is there time to avert passing one or more of these thresholds? What can the geoscience community do to reduce the risks? How important is bottom up versus top down action to ensuring the least worst outcome? These are some of the questions we will debate with world experts in their field and authors of the thought papers on these topics.

The geosciences are currently used by policymakers in a wide variety of areas to help guide the decision-making process and ensure that the best possible outcome is achieved. While the importance of scientific advice and the use of evidence in the policymaking process is generally acknowledged by both policymakers and scientists, how scientific advice is integrated and who is responsible is still unclear.

EU Policymakers frequently highlight institutionalised processes for integrating scientific advice into policy such as European Commission's Group of Chief Scientific Advisors (SAM) and the EU Commission’s Register of Expert Groups. But how efficient and accessible are these mechanisms really?

Some emphasise the need for scientists to have their own policy networks in place so that they can share their research outcomes with policymakers who can then use it directly or pass it on to those responsible for relevant legislation. But from funding applications to teaching and even outreach activities – scientists are often already overloaded with additional tasks on top of their own research. Can they really be held responsible for keeping up with the latest policy news and maintaining a constantly changing network of policymakers as well?

This debate will feature a mixed panel of policymakers and geoscientists who have previously given scientific advice. Some key questions that the panel will debate include:
• How can the accessibility of current EU science-advisory mechanisms be improved?
• Are scientists doing enough to share their research?
• And who is responsible for ensuring that quality scientific evidence is used in policymaking?

Speakers will be encouraged to explain any science advisory mechanism that they highlight (e.g. SAM) to ensure that the debate is understood by all those in attendance.

While the panel and subsequent debate will have an EU focus, it is likely that many of the issues discussed will be applicable to countries around the world.

The ever more challenging work environments and increasing pressures on Early Career Scientists e.g. publish or perish, securing grant proposals, developing transferable skills and many more – and all while having a lack of job security. This puts a big strain on Early Career Scientists and this can lead to neglected mental well-being which in turn increases the risk of developing anxiety, depression or other mental health issues. The graduate survey from 2017 (https://www.nature.com/nature/journal/v550/n7677/full/nj7677-549a.html) shows that 12% of respondents had sought help or advice for anxiety or depression during their PhD.

In this debate we want to discuss: Is there a problem? How ECS can take control of their mental wellbeing and prioritise this in the current research environment? And what support would ECS like to see from organisations like EGU or their employers?

"What counts may not be countable and what is countable may not count". Assessments of scientists and their institutions tend to focus on easy-to-measure metrics related to research outputs such as publications, citations, and grants. However, society is increasingly dependent on Earth science research and data for immediate decisions and long-term planning. There is a growing need for scientists to communicate, engage, and work directly with the public and policy makers, and practice open scholarship, especially regarding data and software. Improving the reward and recognition structure to encourage broader participation of scientists in these activities must involve societies, institutions, and funders. EGU, AGU, and JPGU have all taken steps to improve this recognition, from developing new awards to starting journals around the topic of engaging the public to implementing FAIR data practices in the Earth, environmental, and space sciences, but far more is needed for a broad cultural change. How can we fairly value and credit harder-to-measure, these less tangible contributions, compared to the favoured metrics? And how can we shift the emphasis away from the "audit culture" towards measuring performance and excellence? This session will present a distinguished panel of stakeholders discussing how to implement and institutionalize these changes.

Wed, 10 Apr, 12:45-14:00 / Room E1

Plastic pollution is recognized as one of the most serious and urgent problems facing our planet. Rates of manufacture, use and ultimately disposal of plastics continue to soar, posing an enormous threat to the planet’s oceans and rivers and the flora and fauna they support. There is an urgent need for global action, backed by sound scientific understanding, to tackle this problem.

This Union Symposium will address the problems posed to our planet by plastic pollution, and examine options for dealing with the threat.

The Games Night is a space to gather, socialise, and play some games. The catch is that all the games are based on Geoscience! Bring along your own games or try one of the others in the session and meet the people who created them. This will also be your chance to try games featured in the Games for Geoscience session.

Join us to help put some of the world's most vulnerable places on the map. A mapathon is a mapping marathon, where we get together to contribute to OpenStreetMap - the world's free map.
No experience is necessary - just bring your laptop and we will provide the training. Learn more about crowdsourcing, open data and humanitarian response - we will also provide some tips for how to host a mapathon at your home institution.

Plastic Oceans UK have been experts on plastic pollution for nearly a decade - solving the plastic crisis through their science, sustainability and education programmes. This all began with the award-winning documentary A Plastic Ocean, now available for streaming on Netflix.

Through changing attitudes, behaviours and practices on the use and value of plastics, we can stop plastic pollution reaching the ocean within a generation.

Come along to the screening of A Plastic Ocean to understand the impacts of plastic pollution around the world, what action we can take to stop plastics entering our natural world and pose your questions to the film's producer, Jo Ruxton, at the end of film.

http://plasticoceans.uk/