Global Average Cumulative Mass Balance of Reference Glaciers

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This dataset shows the cumulative change in mass balance of a set of “reference” glaciers worldwide beginning in 1945. The values represent the average of all the glaciers that were measured. Negative values indicate a net loss of ice and snow compared with the base year of 1945. For consistency, measurements are in meters of water equivalent, which represent changes in the average thickness of a glacier.

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A glacier is a large mass of snow and ice that has accumulated over many years and is present year-round. In the United States, glaciers can be found in the Rocky Mountains, the Sierra Nevada, the Cascades, and throughout Alaska. A glacier flows naturally like a river, only much more slowly. At higher elevations, glaciers accumulate snow, which eventually becomes compressed into ice. At lower elevations, the “river” of ice naturally loses mass because of melting and ice breaking off and floating away (iceberg calving) if the glacier ends in a lake or the ocean. When melting and calving are exactly balanced by new snow accumulation, a glacier is in equilibrium and its mass will neither increase nor decrease.

In many areas, glaciers provide communities and ecosystems with a reliable source of streamflow and drinking water, particularly in times of extended drought and late in the summer, when seasonal snowpack has melted away. Freshwater runoff from glaciers also influences ocean ecosystems. Glaciers are important as an indicator of climate change because physical changes in glaciers—whether they are growing or shrinking, advancing or receding—provide visible evidence of changes in temperature and precipitation. If glaciers lose more ice than they can accumulate through new snowfall, they ultimately add more water to the oceans, leading to a rise in sea level. The same kinds of changes occur on a much larger scale within the giant ice sheets that cover Greenland and Antarctica, potentially leading to even bigger implications for sea level. Small glaciers tend to respond more quickly to climate change than the giant ice sheets. Altogether, the world’s small glaciers are adding roughly the same amount of water to the oceans per year as the ice sheets of Greenland and Antarctica. During the last two decades, they added more water overall to the oceans than the ice sheets did.

On average, glaciers worldwide have been losing mass since at least the 1970s, which in turn has contributed to observed changes in sea level. A longer measurement record from a smaller number of glaciers suggests that they have been shrinking since the 1940s. The rate at which glaciers are losing mass appears to have accelerated over roughly the last decade. Year-to-year trends vary, with some glaciers gaining mass in certain years (for example, Wolverine Glacier during the 1980s), but the measurements clearly indicate a loss of glacier mass over time. Trends for the glaciers are consistent with the retreat of glaciers observed throughout the western United States, Alaska, and other parts of the world. Observations of glaciers losing mass are also consistent with warming trends in U.S. and global temperatures during this time period.

Date Created

2016

Last Modified

2016-08

Version

2016-08

Update Frequency

Annual

Temporal Coverage

1945-2015

Spatial Coverage

World

Source

John Snow Labs => EPA's Climate Change Indicators in the United States (US EPA), World Glacier Monitoring Service (WGMS)

Source License URL

John Snow Labs Standard License

Source License Requirements

N/A

Source Citation

N/A

Keywords

Glaciers, Reference Glaciers, Global Glacier Change, Glacier Mass Balance, Fluctuations of Glaciers, Environmental Changes, Glacier Mass Balance

Other Titles

Mass Balance of Reference Glaciers Worldwide, Cumulative Change in Mass Balance of Set Of Reference Glaciers, Mass Balance of Reference Glaciers, Average Cumulative Mass Balance of Reference Glaciers Worldwide

Name Description Type Constraints
Measurement_YearYear of measurementdaterequired : 1
Mean_Cumulative_Mass_BalanceAverage mass of measured glacier. Mesurement unit: Meters of water equivalentnumberlevel : Ratio
Number_of_ObservationsNumber of glaciers observedintegerlevel : Rato
Measurement_YearMean_Cumulative_Mass_BalanceNumber_of_Observations
1945
1946-1.131
1946-1.131
1946-1.131
1946-1.131
1946-1.131
1946-1.131
1946-1.131
1946-1.131
1946-1.131