Glaciers & Sea Level Collaboration Team

Improving the understanding of glaciers, ice caps and the Greenland Ice Sheet to resolve the forcings for and impacts of mass balance changes.

Scope of activities

Action Statement

Motivated by the need for accurate and timely estimates of glacier and ice-sheet contributions to sea-level rise, this team has more recently focused on resolving the forcings for and impacts of mass balance changes. Moving forward, the team will continue to integrate observational capacities and numerical models of Arctic ice, but with a renewed focus on the downstream consequences of glacier runoff, glacier modeling scaled globally, and sea level rise fingerprinting. We will engage government scientists, university scholars, early career scientists and stakeholder NGOs.


GSLCT is focused on observations and model development to better understand changes to land-ice and subsequent impact of these changes on sea level and downstream ecosystems. We continue to discover new ways that glacier ice (and the loss of ice) influences hydrology, ecology and sea level.  The changes in the land-ice system interact with and feedback to other areas of interest to IARPC, including the atmosphere, sea ice, and terrestrial ecosystems.  These interactions occur on a variety of time and space scales, and their consequences are important for enhancing the well-being of Arctic residents, regional and national security, stewardship of the Arctic environment, and the role of the Arctic in the global system.

Team leaders

Zoe Courville
Cold Regions Research and Engineering Lab

Joe MacGregor

Kaitlin Harbeck
NASA Cryospheric Sciences Program (Website)

Performance elements from the Arctic research plan

5.1 Coordinate and integrate observations to improve understanding of the processes controlling the mass balance of Arctic land ice.

  • 5.1.1 Maintain support for aircraft and satellite missions that contribute to long-term observations of land ice, including: Landsat-8, ICESat-2, OIB, and the NASA-ISRO Synthetic Aperture Radar (NISAR) mission.
  • 5.1.2 Enable the collection of ground-based observations and associated aircraft measurements documenting variability of land ice on a variety of spatial and temporal scales, including: the Greenland Ice Sheet Monitoring Network (GLISN), the Oceans Melting Greenland (OMG) mission, the U.S. Geological Survey (USGS) Benchmark Glaciers Program in Alaska (and the the Ice2O project in Alaska.
  • 5.1.3 Support investigator-driven studies of land ice process studies across the Arctic, including ocean-glacier interactions, surface and subglacial hydrology, surface mass balance, local surface melt and refreezing, firn densification, glacial isostatic adjustment, iceberg melting, surface energy budget, and related observations.
  • 5.1.4 Enhance national and international communication and collaboration concerning land ice state and processes, for example, through support of the activities of the SEARCH Land Ice Action Team.

5.2 Improve numerical models to enhance projection of ice loss from Arctic land ice and the consequent impact on global sea level, and to better understand the predictability of these processes.

  • 5.2.1 Enable the development and assessment of ice sheet models, both as stand-alone models and within the context of earth system models, including: the Ice Sheet System Model (ISSM), the Community Ice Sheet Model (CISM), the Community Earth System Model (CESM), the Accelerated Climate Modeling for Energy (ACME) project, the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) and the Land Ice Verification and Validation (LIVV) Toolkit.
  • 5.2.2 Develop data sets to be used as boundary and forcing functions for ice sheet, ice cap, and glacier models, including improving regional reanalyses focused on the greater Arctic, improving global reanalysis systems in ways that are relevant to the Arctic, and promoting joint observation-modeling-reanalysis-forecasting activities.
  • 5.2.3 Support investigator-driven modeling projects designed to understand and parameterize important land ice processes, including studies of mélange rheologies and dynamics, wet and dry firn processes, meltwater infiltration and refreezing, interactions between the glacier front and subglacial outflow plumes, and basal sliding laws.


Photo by Jim Pottinger (PolarTREC 2011), Courtesy of ARCUS

Scientific Achievements

The GSLCT’s achievements include: continuation of, and planning for, future satellite and aircraft observing of ice sheet and glacier status and trends (Performance Element 5.1.1); continued development and refinement of ice sheet models (Performance Element 5.2.1); multiple large datasets that provide valuable model constraints were released including the Surface Mass Balance and Snow on Sea Ice Working Group (SUMup), MakingEarth System Data Records for Use in Research Environments (MEaSUREs), Greenland termini and ice velocity, various IceBridge datasets and Arctic Digital Elevation Models (ArcticDEM) (Performance Element 5.2.2). Several new papers were published [e.g., Beamer et al., 2016; Brinkerhoff et al., 2017; Felikson et al., 2017; Noël et al., 2017] that link observations and models to resolve important processes and coupling between glaciers and downstream systems (Performance Element 5.2.3).

Beamer, J. P., D. F. Hill, A. Arendt, and G. E. Liston (2016), High-resolution modeling of coastal freshwater discharge and glacier mass balance in the Gulf of Alaska watershed: COASTAL FWD AND GVL IN GOA WATERSHED, Water Resour. Res., 52(5), 3888–3909, doi:10.1002/2015WR018457.

Brinkerhoff, D., M. Truffer, and A. Aschwanden (2017), Sediment transport drives tidewater glacier periodicity, Nat. Commun., 8(1), doi:10.1038/s41467-017-00095-5.

Felikson, D. et al. (2017), Inland thinning on the Greenland ice sheet controlled by outlet glacier geometry, Nat. Geosci., 10(5), 366–369, doi:10.1038/ngeo2934.

Noël, B., W. J. van de Berg, S. Lhermitte, B. Wouters, H. Machguth, I. Howat, M. Citterio, G. Moholdt, J. T. M. Lenaerts, and M. R. van den Broeke (2017), A tipping point in refreezing accelerates mass loss of Greenland’s glaciers and ice caps, Nat. Commun., 8, 14730, doi:10.1038/ncomms14730.

Collaborations Between Federal Agencies and the Research Community

The team organized a number of well-attended monthly meetings. The presentations are archived on the IARPC collaborations website. Two of these have involved joint meetings with other collaboration teams (Atmosphere and Marine Ecosystems teams). GSLCT continued to inform and support for the Study of Environmental Arctic Change (SEARCH) Land-Ice group.

Stakeholder Engagement

The SEARCH Land Ice Interaction Team has produced a brief for policymakers on Arctic Land Ice Loss ( and another on links between sea ice loss and land ice loss (

AGU sessions are scheduled (Societal impacts of global cryosphere change and associated mitigation and adaptation policies) to disseminate research broadly.

The National Snow and Ice Data Center (NSIDC) held a Global Land Ice Measurements from Space (GLIMS) workshop to address consistency and automation in glacier mapping.

An international workshop was held in January to discuss the opportunities for basic and applied science using Greenland GPS Network (GNET) – a distributed array of GPS stations around the perimeter of the Greenland Ice Sheet. Many of these involve the collection of time series of processes associated with the variability of the Greenland Ice Sheet mass. A workshop report draft is available.

Facing possible budget shortfalls, USGS engaged with stakeholders to preserve the 50+ year Benchmark Glacier project, which provides the longest-standing observational history of glacier change in the United States. USGS also worked together with the DOI Climate Science Centers to disseminate research related to glacier-ecosystem linkages to decision makers. USGS glaciologists participated in a field trip for congressional staff, briefing them on USGS glacier-climate research.

Priorities for 2018

During FY2018, the GSLCT leadership anticipates increasing the number of inter-collaboration team meetings and hosting a meeting where agencies with smaller glaciological programs brief the community on their efforts to increase collaborative opportunities between small and large agencies.

Accomplishments 2019

Highlight events for this driver for the GSLCT include three meetings held this year, which focused mostly on improved process understanding and modeling of the Greenland Ice Sheet (GrIS) and Arctic glaciers and additional elements of the Arctic cryosphere. These three meetings brought together modelers and observationalists from several disciplines in Earth Science to address outstanding atmospheric, subglacial, and operational questions concerning the present state and future of the Arctic cryosphere.

Communication and collaboration were bolstered by these meetings, which consistently recruited and engaged numerous Federal and non-federal scientists. For example, Federal and academic scientists discussed the challenges of projecting the future of the GrIS, and ice-sheet modelers were exposed to the complexity and variability of sub-daily radiative forcing and sediment discharge across the GrIS.

Priorities 2019

  • New satellite missions are a focus this year. ICESat-2 data are now available, plus, plus there are ongoing developments with Landsat-9 and NISAR (2020).
  • Given federal budget uncertainty, we wish to continue engage agency-level program managers with the GSLCT.
  • Emphasize recent advances in multi-system integrated numerical models and how we can better couple glaciers into Earth system models.

2017 Performance Element Reporting Log

2017 Glaciers & Sea Level Collaboration Team Annual Report

2018 Performance Element Reporting Log

2018 Glaciers & Sea Level Annual Report

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