Sea ice slowing flow of Antarctic glacier suddenly shatters in three days

Sea ice slowing flow of Antarctic glacier suddenly shatters in three days

In just three days in late January, a chunk of ice the size of Philadelphia broke from Larsen B Bay on the Antarctic Peninsula and floated for more than a decade. NASA satellites captured the disintegration between Jan. 19 and 21, when icebergs in the Crane Glacier and adjacent areas disintegrated as sea ice no longer supported their front. Now that it’s easier to melt and accelerate into the ocean, glaciers along the Antarctic Peninsula could directly increase sea levels.

The Larsen Ice Shelf is located in the Weddell Sea in the northeastern part of the Antarctic Peninsula. It is divided into four areas, occupying different bays along the coastline, called Larsen A, B, C and D, extending from north to south, each of which has undergone its own changes over the past few decades.huge mass ice shelf Stop many glaciers from flowing from steep mountains to the sea, causing sea level to rise. Larsen-A first disintegrated in 1995, followed by the sudden partial collapse of Larsen-B in 2002. Larsen-C It was the fourth largest Antarctic ice shelf as of July 2017, when a huge iceberg named A68 broke off from it and caught the world’s attention. Being the southernmost, and therefore least affected by warming, the only part considered relatively stable is Larsen-D.

The loss of 3,250 square kilometers of ice from the Larsen B Ice Shelf in 2002 was blamed on warm seawater melting from below, as well as meltwater on its surface, which also accelerated ice loss. After collapse, only the remnant remains, which is much less stable and prone to further disintegration. It is getting thinner and thinner, which allows the glaciers to flow faster on the landward side. Each winter, sea ice forms in the newly opened areas, but until 2011, the sea ice remained the same year-round and did not melt the following spring. Between 2011 and 2022, the glaciers were somewhat stable because remnant ice shelves and sea ice were permanent and attached to land, blocking their path into the ocean.But the expanse was shattered in three days in January, shattered by NASA’s the earth and aquarium satellite.

Satellite image of the collapse of the Larsen B ice shelf in 2002.Image Source OSU/Flickr

Stephen LermetA professor at Delft University of Technology, specializing in earth sciences and remote sensing, explained to GlacierHub “[it’s] It’s hard to say what exactly caused the sea ice to break up, as the sea ice has been shown to crumbleFeelings before the breakup. ” other Warmer summer temperatures are recommended, and foehn Bringing warm and humid air to the area is part of the reason. The breakup of sea ice this year also occurred earlier than in previous years, which also helped destabilize the ice. despite this, “This rapid rupture is often typical of solid ice, which is usually a frozen collection of loose sea ice segments. Once that breaks down, it disintegrates quickly,” Lhermitte added.

The recent ice breakup in Larsen-B Bay is important because the large glaciers supported by the ice are now exposed to the sea. Unlike melting sea ice and ice shelves, glaciers directly increase sea level. Although sea ice frozen on land is not as effective at stopping the flow of glaciers as the pristine ice shelves that once existed in Larsen-B Bay, it has played a role in minimizing its contribution to sea level rise on the Antarctic Peninsula. the past ten years.

While scientists watch Larsen B disintegrate, a new Learn The published article details the life cycle of the giant iceberg A68 that broke out of Larsen-C in 2017. It is the sixth largest iceberg recorded by satellite observations and is comparable in size to the size of Delaware when it first broke off the ice shelf. A68 ceased to exist after three and a half years, disintegrating rapidly in January 2021 near the South Georgia Islands, east of the southern tip of South America.

The path of the A68 iceberg between July 2017 and March 2021. As it drifted off South Georgia Island, it dumped an estimated 152 billion tons of freshwater and nutrients into the surrounding ocean. (as in figure 1).Credit: Laura Grish

Study lead author, Anne Brackman-FogelmanThose who have studied A68 explained that it caused concern when it calved because “it greatly reduces the area of ​​the remaining ice shelf” [and] Larsen-A and -B have disintegrated. “It is well known that iceberg disintegration affects the stability of the parent ice shelf it leaves behind, but the one left by Larsen-C has remained stable since 2017.

Significant events along the Larsen Ice Shelf are expected to occur more frequently as temperatures rise and climate patterns change. Scientists were able to closely track every part of the Larsen Ice Shelf, documenting ice shelf collapse, the growth of sea ice and the long-term survival of giant icebergs that threaten distant regions. As warming continues, the question of how long the Larsen-D segment will remain stable dominates. So far, its proximity to the South Pole has protected it from climate change. Reducing emissions is important not only for the ice on the Antarctic Peninsula, but also for the larger East and West Antarctic ice sheets.