“Enormous Unleashed: World’s Largest Iceberg Begins its Journey After Decades of Immobility”
A satellite image, taken on November 28, 2023, by NASA’s Terra satellite using the Moderate Resolution Imaging Spectroradiometer (MODIS), reveals Iceberg A-23A, which had been stranded on the seafloor for numerous decades, is now in motion as it drifts northward towards warmer waters where icebergs meet their demise.
For many years, Iceberg A-23A remained hidden from view off the coast of Antarctica, residing in a state of tranquility. However, in November 2023, it garnered attention as it embarked on a northward voyage across the Weddell Sea, drawing nearer to shipping routes, wildlife-inhabited islands, and the warmer waters of the Southern Ocean that spell doom for icebergs.
On November 28, 2023, NASA’s Terra satellite, equipped with the MODIS instrument, captured an image of this colossal iceberg, marking 37 years since its separation from the Filchner Ice Shelf, located to the east of the expansive Ronne Ice Shelf. On this particular day, the iceberg floated in proximity to several islands at the tip of the Antarctic Peninsula, approximately 1,700 kilometers (1,000 miles) from its place of origin.
Having broken free from the Filchner shelf back in 1986, the iceberg eventually found itself grounded on the seafloor of the southern Weddell Sea. For many decades, it remained moored roughly 200 kilometers (120 miles) from the ice shelf. The iceberg’s course, as traced by data available from the U.S. National Ice Center since 2011, can be observed on the accompanying map. Notably, the iceberg initially exhibited a somewhat amorphous path as it contended with the influence of ocean currents and winds. Despite these forces, A-23A remained largely stationary.
In the early 2020s, the iceberg managed to dislodge itself from the seafloor, likely as a result of melting occurring beneath the waterline. By March 2023, it was adrift, joining the company of other sizable icebergs. Since then, during the warmer months of the year, it has traversed the Weddell Sea Gyre—a clockwise-spinning ocean current that propels icebergs from the western Weddell Sea northward.
As of November 24, 2023, the iceberg’s dimensions measured approximately 4,300 square kilometers (1,700 square miles), according to data from the U.S. National Ice Center. This renders it the largest currently-floating iceberg in the world’s oceans. While larger icebergs have come and gone, such as A-68 and A-76, which briefly held this title in 2017 and 2021 respectively, they eventually fractured.
Historically, icebergs in this region, including A-68A and A-76A, have eventually departed from the gyre’s clockwise circulation, venturing into the turbulent waters of the Drake Passage—a stretch of ocean between South America’s Cape Horn and Antarctica’s South Shetland Islands. From there, they typically proceed northward towards the South Atlantic, where they swiftly succumb to the warmth of the region’s waters.
Images courtesy of NASA Earth Observatory, captured by Wanmei Liang using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview, along with data from the Antarctic Iceberg Tracking Database. The Worldview animation was created by Karin Kirk, NASA/JPL-Caltech, employing MODIS imagery from NASA’s Aqua and Terra satellites. This story, authored by Kathryn Hansen with image interpretation by Christopher Shuman, has been made available through NASA/UMBC.
Table of Contents
Frequently Asked Questions (FAQs) about Iceberg Drift
What is Iceberg A-23A and why is it in the news?
Iceberg A-23A is a massive iceberg that had been stuck on the seafloor near Antarctica for decades. It’s in the news because in November 2023, it began drifting northward, drawing attention due to its movement and potential environmental impact.
How large is Iceberg A-23A?
As of November 24, 2023, Iceberg A-23A measures approximately 4,300 square kilometers (1,700 square miles), making it the largest iceberg currently afloat in the world’s oceans.
Why did Iceberg A-23A break free from its location?
The iceberg likely became unstuck from the seafloor in the early 2020s due to melting occurring beneath the waterline, which allowed it to float freely.
What are the potential consequences of Iceberg A-23A drifting northward?
As the iceberg moves closer to shipping lanes, islands inhabited by wildlife, and warmer waters of the Southern Ocean, it could pose risks to navigation, impact local ecosystems, and eventually melt in warmer waters, contributing to rising sea levels.
Are there other notable icebergs that have broken free recently?
In recent years, icebergs like A-68 and A-76 briefly held the title of the world’s largest iceberg before fracturing. These occurrences are not uncommon in regions with significant iceberg activity.
More about Iceberg Drift
- NASA Earth Observatory – Iceberg A-23A
- National Ice Center – Iceberg Tracking
- Climate Change and Icebergs
- Southern Ocean and Environmental Impact
- Antarctic Peninsula
