What We Know About The World’s Biggest Iceberg – BGR

The world’s largest iceberg, A23a, is breaking apart after nearly four decades. This trillion-ton giant measured 1,418 square miles before its recent decline. Scientists confirm the iceberg is now rapidly melting in warmer northern waters.

According to the British Antarctic Survey, A23a had been grounded in the Weddell Sea since 1986. It finally broke free from the seafloor in 2020. The iceberg’s journey marks a significant event in Antarctic ice dynamics.

A23a’s Historic Journey and Final Breakdown

A23a originally calved from the Filchner-Ronne ice shelf in 1986. Its immense size caused it to become stuck almost immediately. The iceberg remained grounded for nearly forty years.

In 2020, the iceberg finally broke loose from the seafloor. It began drifting northward through the Southern Ocean. Ocean currents initially trapped it in a slow spin for several months.

By May 2025, A23a had cleared the Antarctic continental shelf. It entered progressively warmer waters as it moved northward. The higher temperatures accelerated its disintegration dramatically.

The iceberg has now lost more than half its original mass. This loss means it no longer holds the title of world’s largest iceberg. The remaining fragments continue to break apart rapidly.

New Largest Iceberg and Scientific Significance

The new record holder is iceberg D15a at 1,158 square miles. While smaller than A23a at its peak, D15a remains enormous. It measures nearly twice the size of Greater London.

Scientists monitor these large icebergs for multiple reasons. Their movements help researchers understand ocean currents. The melting process also provides data on freshwater input into oceans.

The calving and movement of icebergs are natural processes. But scientists watch for changes in frequency and size. These observations contribute to climate change research.

Large icebergs can disrupt shipping routes and wildlife habitats. Their gradual disappearance often attracts scientific interest. The journey of A23a has been particularly noteworthy due to its longevity.

The disintegration of the world’s largest iceberg represents both a natural cycle and a valuable scientific opportunity. Researchers continue monitoring A23a’s remnants as they drift toward their eventual complete melting in the southern Atlantic.

Thought you’d like to know

How big was the A23a iceberg at its largest?

A23a measured approximately 1,418 square miles at its peak. That made it larger than the entire island of Long Island. It also weighed an estimated one trillion tons.

Where was A23a located for most of its existence?

The iceberg was grounded in the Weddell Sea near Antarctica. It remained stuck there for nearly 40 years. The shallow seafloor prevented it from drifting northward earlier.

What caused A23a to finally break free?

Gradual melting reduced its draft enough to float free. Ocean currents eventually dislodged it from the seafloor. This process began in 2020 and continued until 2025.

Is iceberg calving related to climate change?

Iceberg calving is a natural Antarctic process. Scientists monitor whether climate change affects frequency or size. No direct link has been established for A23a’s original calving.

What will happen to the remaining pieces of A23a?

The fragments will continue moving north into warmer waters. They will gradually melt completely over coming months. The freshwater will eventually disperse into the ocean.

How do scientists track large icebergs?

Researchers use satellite imagery and GPS tracking devices. The British Antarctic Survey regularly monitors major iceberg movements. This data helps understand ocean currents and ice behavior.

Trusted Sources

British Antarctic Survey, European Space Agency, National Ice Center, NASA Earth Observatory