Greenland Ice Sheet

Arctic Report Card: Update for 2025

Twenty years of tracking rapid Arctic warming and change

Archive of Previous Arctic Report Cards

K. Poinar¹, J. E. Box², B. E. Smith³, T. G. Askjaer⁴, T. L. Mote⁵, B. D. Loomis⁶, B. C. Medley⁶, K. D. Mankoff^7,8, and R. S. Fausto²

¹University at Buffalo, Buffalo, NY, USA
²Geological Survey of Denmark and Greenland, Copenhagen, Denmark
³University of Washington, Seattle, WA, USA
⁴Danish Meteorological Institute, Copenhagen, Denmark
⁵Department of Geography, University of Georgia, Athens, GA, USA
⁶Goddard Space Flight Center, NASA, Greenbelt, MD, USA
⁷Goddard Institute for Space Studies, NASA, New York, NY, USA
⁸Autonomic Integra, New York, NY, USA

Headlines

The mass balance of the Greenland Ice Sheet for 2025 was -129 ± 50 Gt, showing less loss than the 2003-24 annual average of -219 ± 16 Gt but continuing the long-term trend of net loss.
Above-average snowfall and below-average melt, despite above-average ice discharge (all compared to the 1991-2020 average), contributed to the ice sheet losing less mass this year than typical.
This loss of ice contributes to global sea-level rise, alters regional ocean circulation in the North Atlantic, and changes nutrient levels in local marine food webs.
Sustained, routine measurement of the mass balance of the Greenland Ice Sheet is crucial for understanding current changes and projecting future changes, which support effective local to global planning and adaptation.

Introduction

The Greenland Ice Sheet is susceptible to climate change. Total loss of the Greenland Ice Sheet would raise global sea levels by approximately seven meters (Morlighem et al. 2017). Greenland ice loss affects human societies and environments globally, including through coastal erosion, saltwater intrusion, habitat change, tidal flooding, heightened storm surges, and permanent seawater inundation. Local and regional impacts of negative Greenland Ice Sheet mass balance include potential disruption of North Atlantic thermohaline circulation, which portends local Arctic sea ice expansion and northern European cooling (van Westen et al. 2024). Enhanced runoff also changes nutrient fluxes into marine environments, affecting marine food webs and fisheries (Hendry et al. 2019).

Net loss of ice from the Greenland Ice Sheet has occurred every year since the late 1990s (Mouginot et al. 2019; Mankoff et al. 2020; Fig. 1a). We summarize the observed mass change and the factors driving it for 2025.

Mass balance of the Greenland Ice Sheet from GRACE-FO and ICESat-2 from 2004-2024, mass balance over the 2025 mass balance year, and histogram. — **Fig. 1.** (a) Full observational record of the mass balance of the Greenland Ice Sheet from GRACE/GRACE-FO (blue) and ICESat-2 (green), with measurement uncertainties shaded. (b) Mass balance over the 2025 mass balance year (GRACE-FO, blue) and through 2 April (ICESat-2, green) (bold lines) and 2003-24 (thinner lines). (c) Histogram of annual mass balance from 2003-24 from GRACE/GRACE-FO, with the GRACE-FO 2025 mass balance of -129 ± 50 Gt in black.

Ice-sheet mass balance

The Greenland Ice Sheet gains mass primarily through snowfall and loses it primarily through runoff and ice discharge (calving of icebergs and melting of glacier marine termini) into the ocean. The sum of these quantities (and including other minor mass change contributors) is the ice-sheet mass balance: the net gain or loss of ice over a period, typically one year. We report on the 2025 mass balance year, 1 September 2024 through 31 August 2025.

The Gravity Recovery and Climate Experiment Follow-on (GRACE-FO) satellite mission measured a 2025 mass balance of -129 ± 50 Gt (Fig. 1b). The observed mass balance was less negative than the 2003-24 annual average measured by GRACE/GRACE-FO of -219 ± 16 Gt (mean ± 1 st. dev.; Fig. 1c).

The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) mission measures the surface height of the ice sheet over time, which we convert to mass change. Adequate data were not available to evaluate the full 2025 mass balance year. From 1 September 2024 to 2 April 2025, however, this ICESat-2 method measured a mass balance of -2 ± 56 Gt (mean ± 1 st. dev.; Fig. 1b), which underestimates the annual loss because the period does not include the melt season. The ICESat-2 partial-year mass balance is 102 Gt below the independent GRACE-FO measurement over the same time period (Fig. 1b) and is slightly below the ICESat-2 1 September-2 April average of +21 ± 40 Gt (mean ± 1 st. dev) over 2020-23. The ICESat-2 annual average for full mass balance years (2020-24) was -134 ± 62 Gt (mean ± 1 st. dev) and follows a steady trend of year-over-year ice loss (Fig. 1a).

Contributions to the observed loss of ice mass

Surface mass balance (SMB) comprises mass input to the ice sheet from snowfall and refrozen rainfall, minus mass loss from surface runoff, sublimation, and evaporation. SMB is influenced by air temperature, precipitation, melt, and surface reflectivity (albedo), for which we summarize observations over the 2025 mass balance year.

In situ rain and snowfall (hereafter, “precipitation”) is observed at 11 coastal and 10 inland ice sheet stations (see Methods and data). Precipitation totals observed at coastal stations during the 2025 mass balance year were generally above the 1991-2020 average. Autumn (September-November 2024) precipitation was slightly below average, while winter (December 2024-February 2025) precipitation was significantly above average at coastal stations, especially in the northeast, but near average at inland stations. Spring (March-May 2025) precipitation was close to average. Summer (June-August 2025) precipitation was above average, as also shown in the precipitation analysis (see essay Precipitation, Fig. 1). Several inland stations recorded notable June snowfall amounts (Fig. 2).

Snowfall accumulation graphs. — **Fig. 2.** Snowfall accumulation measured at PROMICE GC-Net stations during 2024/25 (blue; see Fig. 3 for locations), compared to 1999-2020 (black/gray).

Monthly mean air temperatures measured at 34 weather stations across Greenland (see Methods and data) during the 2025 mass balance year were generally above the 1991-2020 average (Fig. 3). Autumn, winter, and spring temperatures were above average, especially in the north and west. Summit Station reached a record high monthly mean temperature in April, and a heat wave in late May pushed temperatures well above average on the east coast. Altogether, spring temperatures were above average. These warm patterns ended by June; summer temperatures were close to average.

Map of Greenland with data. — **Fig. 3.** Temperature anomaly in the four seasons (colored pie charts) and the total 2025 mass balance year (surrounding colored circles, when all four seasons are available) at coastal weather stations. Locations of inland weather stations operated by PROMICE GC-Net (Fig. 2) are in green.

Temperature and snow cover influence ice melt. The overall extent of ice sheet surface melt was close to the 1991-2020 average (Fig. 4a), although this manifested as an above-average number of observed melt days in most locations (Fig. 4b). The above-average summertime snow accumulation likely helped limit the melt extent by raising the albedo, which helps protect the ice sheet from melting by reflecting sunlight away. Early in the melt season (May-June), albedo was near or below average, but summer snowfall raised (brightened) it above the average. Albedo dropped below average in late August, coincident with observed smoke from North American wildfires along the west coast of Greenland. Particulates from smoke, if deposited on the ice, can lower the albedo and enhance melt (Keegan et al. 2014).

Surface melt extent from April 1-Oct 31 and map of Greenland with surface melt days overlaid. — **Fig. 4.** (a) Daily surface melt extent over the 2025 mass balance year (omitting November-March), including autumn 2024 (red) and spring/summer 2025 (blue). (b) Number of surface melt days from 1 April to 31 August 2025, as an anomaly with respect to 1991-2020.

The mass of ice flowing out of Greenland’s glaciers into the ocean is termed ice discharge. At the ice-ocean boundary, ice either calves off as icebergs or melts directly into the ocean. An ice sheet that is in balance loses the same amount of ice through discharge as it gains from SMB. On the Greenland Ice Sheet, however, solid ice discharge has exceeded SMB every year since the mid-1990s. We report an approximation of ice discharge obtained by measuring ice flux through specific gates across the ice sheet (Mankoff et al. 2020). In the 2025 mass balance year through 20 August 2025, this discharge was 491 ± 17 Gt/yr (mean ± 1 st. dev.; Fig. 5), approximately 1 st. dev. above the 1991-2020 mean of 458 ± 27 Gt/yr.

Solid ice discharge graphed and histogram. — **Fig. 5.** (a) Solid ice discharge across the Greenland Ice Sheet observed over the mass balance years 1991-2020 (gray lines) with mean ± 1 st. dev. (orange) and 2025 (black line). (b) Histogram of the average annual discharge from 1991-2024, with 2025 discharge in black.

Methods and data

The GRACE (Gravity Recovery and Climate Experiment, mid-2002-17) and GRACE-FO (Follow On, 2018-present) satellite missions detect gravity anomalies to measure changes in ice mass (GRACE/GRACE-FO Level-2: JPL RL06.1 doi:10.5067/GFL20-MJ061; Technical Notes 13 & 14: https://podaac.jpl.nasa.gov/gravity/gracefo-documentation). We apply a regional averaging kernel (Wahr et al. 1998) to the Level-2 products that is consistent with the Jet Propulsion Laboratory and Goddard Space Flight Center mascon solutions (Watkins et al. 2015; Loomis et al. 2019). The source data include peripheral glaciers that are not part of the Greenland Ice Sheet. We scale our results by 0.84 to exclude these glaciers (Colgan et al. 2015).

Changes in ice surface elevation measured by ICESat-2 reflect ice mass change as well as changes in firn air content and SMB. We calculate mass change by correcting quarterly ICESat-2 elevation measurements (Smith et al. 2023) for these anomalies (Medley et al. 2022), then following the processing strategy for ICESat-2 level-3B products (Smith 2023) to calculate non-SMB-driven elevation change. We then add monthly SMB to estimate total mass change. We approximate the error as 0.14 times the SMB anomaly estimates (Medley et al. 2022).

Weather data are obtained from 20 Danish Meteorological Institute (DMI) land-based weather stations, 12 stations owned by Mittarfeqarfiit A/S, and Summit Station courtesy of NSF/NOAA GEOSummit. Ten automatic weather station transects from the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) at the Geological Survey of Greenland and Denmark (GEUS) provide temperatures and SMB measurements, following Fausto et al. (2021).

Surface melt duration and extent are derived from daily Special Sensor Microwave Imager/Sounder (SSMIS) 37 GHz, horizontally polarized passive microwave radiometer satellite data (Mote 2007). On 24 September 2025, this instrument was decommissioned, and with it the capability to produce this melt product (see essay Assessing the State of the Arctic Observing Network).

Ice discharge rates are derived by PROMICE from measurements of ice surface velocity from Sentinel-1, estimates of ice thickness and density, and the assumption of plug flow (Mankoff et al. 2020). We estimate discharge at gates a few kilometers upstream of each terminus, which omits frontal advance or retreat, as well as ice loss from melting between the gates and termini.

Acknowledgments

Sentinel-3 albedo data processing was supported by the European Space Agency (ESA) EO Science for Society contract CCN 4000125043/18/I-NB and the ESA Network of Resources via Polar View and Polar TEP.

Jacob C. Yde, Western Norway University of Applied Sciences, Sogndal, Norway provided information on local and regional impacts of ice melt.

References

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Fausto, R. S., and Coauthors, 2021: Programme for Monitoring of the Greenland Ice Sheet (PROMICE) automatic weather station data. Earth Syst. Sci. Data, 13(8), 3819-3845, https://doi.org/10.5194/essd-13-3819-2021.

Hendry, K. R., and Coauthors, 2019: The biogeochemical impact of glacial meltwater from Southwest Greenland. Prog. Oceanogr., 176, 102126, https://doi.org/10.1016/j.pocean.2019.102126.

Keegan, K. M., M. R. Albert, J. R. McConnell, and I. Baker, 2014: Climate change and forest fires synergistically drive widespread melt events of the Greenland Ice Sheet. Proc. Natl. Acad. Sci. U.S.A., 111(22), 7964-7967, https://doi.org/10.1073/pnas.1405397111.

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January 31, 2026