Glaciers are mammoth structures of fallen snow that compress into ice masses. Over time, glaciers shrink due to ice melt, evaporation and calving, a process where large chunks of ice break off the edge of the glacier.
Recent studies show that the rate of shrinkage has increased over the past 20 years. So what does that mean for our planet?
About the Shrinking Glaciers
Tracking how quickly glaciers shrink helps scientists predict how quickly sea levels may rise, which is affected by increasing temperatures due to climate change. But estimating the rate of shrinkage is not easy.
In the past, researchers relied on field studies of a few hundred ice glaciers out of the more than 200,000 that exist on earth. This small sampling was paired with satellite data that offered limited resolution.
Recently more accurate technology has been introduced in the form of myriad satellite and aerial images which were used to survey 217,175 glaciers accounting for nearly every one that exists on Earth.
A 20-year archive of images collected from NASA’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was particularly useful as it supplied researchers with data that allowed them to get a more definite idea of the rate of shrinkage.
It was found that glaciers lost an average of 293.7 billion tons of mass per year between 2000 and 2019 accounting for about 21% of the sea level rise within that time frame. The data also revealed that glacier mass loss has been accelerating, increasing by about 52.8 billion tons per year. This may account for the rapid increase in sea level rise.
The findings from the study were compared against previous data collected to come up with similar results with reduced margins of error. This is due to the ASTER’s ability to capture images from a variety of angles on the visible and near infrared spectrum. The images can then be used to recreate a 3D topography of the Earth’s surface including the structure of the glaciers across the planet.
While the current data is more accurate, there are factors that contribute to some chance of error. For example, glaciers not only lose ice, they lose firn, a partially compacted snow usually found on the top of glaciers. The recent study did not differentiate the snow from the firn when estimating mass loss making for a large source of uncertainty.
Another concern is that not all glaciers lose mass at the same rate. Loss rates vary due to locations and climate conditions around the world. Globally complete sets of observations are necessary in providing more accurate data.
Tracking global glacier mass loss will help scientists predict global sea level rises, but local loss must also be accounted for as this data can be useful in determining the availability of water resources and the likelihood of natural disasters such as avalanches and floods. The technology will continue to be refined so that researchers are able to determine loss rates on both a local and global level. It is hopeful that their findings will be useful in making the planet a better place to live in.