Extensive Melting in Antarctic Ice Shelves Results in Trillions of Tons of Ice Loss

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A recent study has shed light on a concerning trend in Antarctica, where numerous vital ice shelves have experienced significant reductions in size, with trillions of tons of ice vanishing into the ocean. This investigation, which examined the period from 1997 to 2021, revealed startling findings regarding the state of these essential barriers between Antarctica’s colossal glaciers and the open sea.

The study identified that a total of 48 Antarctic ice shelves have diminished by a minimum of 30% since 1997, and a staggering 28 of them have lost more than half of their ice during this timeframe. Of the 162 ice shelves encompassing the continent, 68 exhibited noticeable shrinkage, while 29 underwent growth. Remarkably, 62 remained relatively unchanged, and three displayed mass loss that did not constitute a significant trend, according to the findings published in Science Advances.

The melted ice from these shelves, typically restraining larger glaciers, ultimately finds its way into the sea. Scientists express deep concern that the accelerated melting caused by climate change in Antarctica and Greenland could lead to a perilous and substantial rise in sea levels over the course of many decades and centuries.

University of Colorado ice scientist Ted Scambos emphasized the importance of understanding the precise quantity and manner in which ice is vanishing from these protective floating shelves, as it is a crucial step in comprehending Antarctica’s evolving dynamics.

A pivotal factor contributing to sea-level rise is the alteration in the composition of ocean water in what is referred to as “the key region of Antarctica for sea level rise.” This phenomenon not only increases ocean height but also decreases its density and salinity.

The study identified several significant factors responsible for the ice shelf loss, including the breakage of colossal icebergs in 1999, 2000, and 2002, comparable in size to the state of Delaware. Additionally, the research examined the influence of warm water beneath the ice shelves.

Ice shelves, described as the “gatekeepers,” serve as floating extensions of glaciers, impeding the rapid flow of larger glaciers into the ocean, as pointed out by the lead author of the study.

In total, the Antarctic ice shelves witnessed a staggering loss of approximately 8.3 trillion tons (7.5 trillion metric tons) of ice over the 25-year study period, equivalent to around 330 billion tons (300 billion metric tons) annually, consistent with earlier research. However, the real significance lies in the patterns of individual shelf loss, with four glaciers on the Antarctic Peninsula and the western side losing over a trillion tons each.

One notable example is the Wordie ice shelf, which, following a significant collapse in 1989, has lost an astounding 87% of its remaining mass since 1997. Its neighboring Larsen A and Larsen B ice shelves have experienced losses of 73% and 57%, respectively. The largest among the Larsen ice shelves, Larsen C, has seen a reduction of 1.8 billion tons (1.7 trillion metric tons) of ice, equivalent to roughly one-eighth of its total mass.

However, the most significant loss has occurred in the Thwaites ice shelf, which holds back the rapidly melting glacier ominously nicknamed “Doomsday.” This shelf has lost a staggering 70% of its mass since 1997, totaling approximately 4.1 trillion tons (3.7 trillion metric tons) of ice, all of which has flowed into the Amundsen Sea.

The study noted that the ice shelves showing growth were primarily situated on the continent’s eastern side, where weather patterns isolate the land from warmer waters. Nevertheless, the rate of growth in these eastern ice shelves was slower compared to those in the west that were experiencing ice loss.

While it is challenging to directly attribute individual ice shelf losses to human-induced climate change, the study underscores the inevitability of ongoing attrition as the planet continues to warm.

This study serves as a stark reminder of the profound consequences of climate change on Antarctica’s ice shelves and the potential repercussions for global sea levels.

For further coverage of climate-related news, visit AP’s climate coverage.

Follow Seth Borenstein on Twitter at @borenbears.

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