Vanishing ice is warping Earth's crust

The ocean in Greenland is formed by ice calving from the fracture area of a glacier. The melting of glacial ice like this is leading to the destruction of Earth's crust. (Image credit to Jason Edwards/Getty Images).
The melting of Earth's Polar Ice is causing the crust to warp.

Although the shape shift is subtle, it can be seen hundreds of miles from the ice sheet. Researchers might be able monitor this shift to better understand the effects of climate change on sea level. Understanding the warping is important because scientists must be able correct for ground motion in measuring other geological processes.

Scientists knew from the beginning that ice melts and crust beneath it changes. Imagine raising your head from a memory foam cushion. As your head lifts, the pillow will gradually rise, and it will continue to move even after you have vacated the mattress. Similar things happen when a glacier retreats. Slowly, the crust below, no longer supported by all that weight, rises up. This process is known as isostatic rebound and is very slow. Some high-latitude areas still show signs of rebounding from the retreating ice sheets at the end of last ice age.

Related: Antarctica: Ice-covered bottom of the World (Photos).

Climate change is causing a rapid loss of ice in the polar regions. According to a 2020 paper in The Cryosphere, the Antarctica, Greenland, and mountain glaciers ice loss increased by 60% between 2000 and 2010. The crust's shape is being affected by this melt, as was the case with the Ice Age. Research has mainly focused on crust changes under and around ice sheets. Researchers do not focus on the effects further away, but they only study vertical changes in crust shape. However, the crustal motion following ice loss is three-dimensional. This means it also shifts horizontally.

Sophie Coulson is a postdoctoral researcher at Los Alamos National Laboratory, New Mexico. She conducted the research while she was at Harvard University. Her goal was to look at the global impact of the 21st Century's ice loss in 3D. Her colleagues and she used satellite data from 2003 to 2018 to examine tiny changes in the crust and compare those changes to ice loss in Antarctica and Greenland.

In many cases, they found that the crust's horizontal movement was greater than the crust's vertical movement (uplift). It was highly dependent on the amount of ice lost each year. However, in most cases, North America experienced more horizontal than vertical movement. In 2012, the horizontal creep was at its highest point, reaching 0.017 inches (0.45 m). This movement averaged around 0.01 mm for the entire continent in low-loss decades.

In the 2000s, ice rapidly retreated from the Antarctic peninsula and West Antarctica. However, East Antarctica saw an increase in ice. The Earth's crust was able to average out the gains and losses, so the majority of the deformation occurred in the southern Pacific. It was different in the Northern Hemisphere. The average horizontal motion in the Northern Hemisphere each year was 0.015 inches (0.4mm). This is due to ice loss at the northern latitudes. This includes movement of up to 0.01 inches (3.3% mm) in Canada and the United States and up to 0.008 in Europe and Scandinavia (0.2 mm).

Although these numbers might seem small, they add up over time. This warping could have an impact on how future ice losses play out.

Coulson explained to the Harvard Gazette that in some areas of Antarctica, rebounding of crust can alter the slope of the under-ice sheet bedrock, which can impact the ice dynamics. A steeper slope indicates a faster flow toward the sea.

Original publication on Live Science