Regional Assessments of Glacier Mass Change (RAGMAC)

(2020 – 2023)

Working Group co-chairs

Michael Zemp, University of Zurich, Switzerland
Matthias H. Braun, University of Erlangen-Nürnberg, Germany
Fanny Brun, Utrecht University, Netherlands
Alex Gardner, NASA Jet Propulsion Laboratory, USA
Bert Wouters, Institute for Marine and Atmosphere Research and Delft University of Technology, Netherlands
Geir Moholdt, Norwegian Polar Institute, Norway
Regine Hock, University of Alaska Fairbanks, USA

Other Working Group members

Listed under Work Packages below


Retreating and thinning glaciers are icons of climate change and impact the local hazard situation, regional runoff as well as global sea level. For past reports of the Intergovernmental Panel on Climate Change (IPCC), regional glacier change assessments were challenged by the small number and heterogeneous spatio-temporal distribution of in situ measurement series and uncertain representativeness for the respective mountain range as well as by spatial limitations of current satellite altimetry (only point data) and gravimetry (coarse resolution). Towards IPCC SROCC, there have been considerable improvements with respect to available geodetic datasets. Geodetic volume change assessments for entire mountain ranges have become possible thanks to recently available and comparably accurate DEMs. At the same time, new spaceborne altimetry (ICESat-2) and gravimetry (GRACE-FO) missions are in orbit and about to release data products to the science community. This opens new opportunities for regional evaluations of results from different methods as well as for truly global assessments of glacier mass changes and related contributions to sea-level rise. At the same time, the glacier research and monitoring community is facing new challenges related to data size, formats, and availability as well as new questions with regard to best practises for data processing chains and for related uncertainty assessments.

Objectives and work packages

The overall goal of this working group (WG) is bringing together the research community that is assessing regional glacier mass changes from various observation technologies and to come up with a new consensus estimate of global glacier mass changes and related uncertainties. The WG is organized in three work packages (WPs), two related to different remote sensing technologies and a third that aims at regional comparisons of corresponding results:

WP1: Glacier mass changes based on glaciological and geodetic (DEM differencing) methods

Co-leads: Matthias H. Braun (University of Erlangen-Nürnberg, Germany) and Fanny Brun (Utrecht University, Netherlands)
Members (in alphabetical order): Liss M. Andreassen (Norwegian Water Resources and Energy Directorate, Norway), Anthony Arendt (University of Washington, USA), Jacqueline Bannwart (University of Zurich, Switzerland), Etienne Berthier (University of Toulouse, France), Tobias Bolch (University of St Andrews, UK), Matthias Huss (ETH Zurich, Switzerland), Andreas Kääb (University of Oslo, Norway), Robert McNabb (University of Oslo, Norway), Brian Menounos (University of Northern British Columbia, Canada), Laura Thomson (Queen’s University, Canada), Michael J. Willis (University of Colorado Boulder, USA), Michael Zemp (University of Zurich, Switzerland)

  • Develop best practises for geodetic estimates of glacier mass changes and related uncertainties.
  • Improve the global coverage of geodetic glacier change assessments.

WP2: Glacier mass changes based on altimetry and gravimetry

Co-leads: Alex Gardner (NASA Jet Propulsion Laboratory, USA), Bert Wouters (Institute for Marine and Atmosphere Research and Delft University of Technology, Netherlands), Geir Moholdt (Norwegian Polar Institute, Norway)
Members (in alphabetical order): Martin Horwath (TU Dresden, Germany), Noel Gourmelen (University of Edinburgh, UK), Andreas Groh (TU Dresden, Germany), Andreas Richter (TU Dresden, Germany), Ingo Sasgen (AWI, Bremerhaven, Germany)

  • Develop best practices for the propagation of errors in glacier mass-change estimates derived from satellite altimetry and gravimetry.

WP3: Regional comparisons of glacier mass changes from different methods

Co-leads: Regine Hock (University of Fairbanks, US) and another WG member (tbd)
Members: all of WP1, WP2, and WP3

  • Encourage regional assessments of glacier mass changes.
  • Foster open and free access to glacier data.
  • Define a common framework for regional mass change estimates.
  • Develop a consensus estimate of regional and global mass changes from glaciological, geodetic, altimetric, and gravimetric methods.

Deliverables and milestones

  • Q4 2019: Research topic in Frontiers in Earth Sciences
  • Q1 2020: Official announcement of WG and virtual kick-off meeting
  • Q2 2020: Initial workshops of WG1 and WG2
  • Q4 2020: Round robin experiment WG1
  • Q2 2021: Data production coordination
  • Q4 2021: Method papers from WG1 and WG2.
  • Q2 2022: Data production coordination
  • Q1 2023: Consensus estimate paper from WG3.
  • Periodical conference sessions, e.g. at EGU, AGU

Towards the end of the WG, we aim to present a new consensus estimate of global glacier mass changes based on all available assessments from glaciological, geodetic, altimetric, and gravimetric methods.


Research topic “Observational Assessments of Glacier Mass Changes at Regional and Global Level” in Frontiers in Earth Sciences:


The present proposal was prepared by a core team of scientists currently active in regional glacier change assessments. Working Group Membership is open to everybody who has expertise in and is working actively on regional or global mass-change assessments. To keep the group focused, all WG Members are expected to
a) actively contribute to one or several of the WG objectives as described above, and
b) participate in annual WG meetings (typically held at major conferences; remote participation is possible) and, if possible, periodic teleconferences in between.

Open data sharing is a key element of this Working Group. Thus, WG members are required to make any relevant new (including yet unpublished) data available to the Members of all relevant Work Packages. In addition, all data are expected to be submitted to an international data repository, typically after publication.

If you are interested in joining the WG, please contact the co-chairs including a brief summary how you intend to contribute to the WG’s goals and which work package(s) you would like to join.

January 2020