Arctic Glacier Mass Balance

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Caption: Key Points: The loss of land-based ice in the Arctic has accelerated in recent decades, contributing to global sea level rise. About the Indicator: This indicator provides information on the cumulative change in mass balance of glaciers over time. Glacier mass balance data are calculated based on a variety of measurements at the surface of a glacier, including measurements of snow depths and snow density. The net balance is the average mass balance of the glacier from data collected over a glaciological year, the time between the end of the summer ablation season from one year to the next. The overall Arctic average change in mass balance declined, consistent with the retreat of glaciers observed in other parts of the world. The Engabreen glacier, situated near the coast of Norway, gained mass over the period of record and is more strongly influenced by precipitation than glaciers elsewhere in the Arctic. Rapid changes are occurring across the Arctic where air temperatures are warming twice as fast as the global average temperature. The loss of land-based ice in the Arctic has accelerated in recent decades and since at least 1972, the Arctic has been the dominant source of global sea-level rise. After Greenland, the largest contributor to global sea-level rise from Arctic land ice, are the Arctic’s glaciers. Why It Is Important: Glaciers provide visible evidence of changes in temperature and precipitation. If increases in greenhouse gas concentrations continue at current rates, it is expected that many of the smallest glaciers across the Arctic would disappear entirely by mid-century.

This panel, "Arctic Glacier Mass Balance" is an original panel provided by Mike Kolian, with contributions from Michael Zemp. Please contact Mike Kolian for any questions or additional information regarding this figure.

Analysis Methods and Tools

This figure panel was created using the following analysis methods:

• Mass balance estimates were divided by 1,000 to convert millimeters to meters.
• Cumulative mass balance for each individual glacier was calculated by adding net balances from (or backwards from) 1970, which we've established as a consistent baseline (zero) point across all eight glaciers.
• The cumulative mean mass balance was determined by calculating the annual mean mass balance across the eight glaciers (or as many of the eight had data in a given year), then adding these mean net balances from year to year. The mean line was also adjusted to use 1970 as a common zero point.

Note: Glacier mass balance data are calculated based on a variety of measurements at the surface of a glacier, including measurements of snow depths and snow density. The net balance is the average mass balance of the glacier from data collected over a glaciological year, the time between the end of the summer ablation season from one year to the next. These measurements help glaciologists determine changes in snow and ice accumulation and ablation that result from snow precipitation, snow compaction, freezing of water, melting of snow and ice, calving (i.e., ice breaking off from the tongue or leading edge of the glacier), wind erosion of snow, and sublimation from ice (Mayo et al., 2004). Both surface size and density of glaciers are measured to produce net mass balance data. These data are reported in meters of water equivalent (mwe), which corresponds to the average change in thickness over the entire surface area of the glacier. Because snow and ice can vary in density (depending on the degree of compaction, for example), converting to the equivalent amount of liquid water provides a more consistent metric.

They used Microsoft Excel to analyze the data. The operating system macOS Big Sur Version 11.3 was used to perform the analysis.

The data was visualized using the following methods:

• The cumulative mass balance for each individual glacier was plotted as a time series, along with the eight-glacier average.
• A map depicting the locations of each glacier was placed alongside the chart, accompanied by a color-coded legend.

and with the following software:

SigmaPlot , Adobe Photoshop

These methods are published in

• WGMS (World Glacier Monitoring Service). 2015. Global glacier change bulletin no. 1 (2012–2013). Zemp, M., I. Gärtner-Roer, S.U. Nussbaumer, F. Hüsler, H. Machguth, N. Mölg, F. Paul, and M. Hoelzle (eds.). ICSU (WDS)/IUGG (IACS)/UNEP/UNESCO/WMO. Zurich, Switzerland: World Glacier Monitoring Service
• Østrem, G., and M. Brugman. 1991. Glacier mass-balance measurements: A manual for field and office work. National Hydrology Research Institute (NHRI), NHRI Science Report No. 4.

For full details, please download the full metadata record available on the “Full Record” tab.