Glacier Melt's Contribution To Rising Sea Levels

New Methods Track Over 97 Percent Of Planet's Glaciers

4 May 2021 by The Water Diplomat

New analysis of almost every glacier on the planet indicates that annual rates of glacier thinning have “nearly doubled” in the past 20 years.

The paper found that, on average, glaciers lost 4 Percent of their volume over 20 years. But the picture varied across time and from region to region.

This rate of ice melt is believed to be the second largest contributor to sea-level rise in the 21st Century and is greater than that of either Greenland or Antarctic ice sheets.

Lead author Romain Hugonnet, of the University of Toulouse, said the data was an urgent warning. “A doubling of the thinning rates in 20 years for glaciers outside Greenland and Antarctica tells us we need to change the way we live. We need to act now,” he said. “It can be difficult to get the public to understand why glaciers are important because they seem so remote, but they affect many things in the global water cycle including regional hydrology, and by changing too rapidly, can lead to the alteration or collapse of downstream ecosystems.”

The study used data collected from NASA’s Terra satellite and achieved coverage of over 97 Percent of all glaciers, making it the most accurate and comprehensive assessment of the world’s 217,175 glaciers to date. The results offer strong evidence that there is an urgent requirement for swift action to stem greenhouse gas emissions.

In addition to the new spatial information offered through the NASA data, the study has assessed elevation and mass change observations at an individual glacier scale, providing a very detailed record of how glaciers are responding to the variability in climate and, more importantly, rising temperatures.

The new study will enable more precise measurement of a glacier thereby providing more accurate information on the glacier’s contribution to sea level rise.

The new study assesses that since 2000, the world’s glaciers have lost over 265 billion tonnes of ice each year. The study makes the assumption that all that melt has reached the ocean and further calculates that such glacier melt contributed about 0.75 millimetres of seal level rise every year.

Further, the information can be “regionalized” and the overall loss from glaciers can be compared to the loss from melting ice sheets.

The authors warn that the study should be used as “further scientifically rigorous evidence” of “the urgent need for rapid and collective action to reduce the dumping of greenhouse gases in our planet’s atmosphere”.

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