Antarctica produced colossal glaciers millions of years earlier than previously thought. How is this possible?

For decades, scientists have been monitoring how massive ice chunks break off from the Antarctic ice cap and drift, similar to the largest iceberg in the world, A23a, which is currently heading towards South Georgia Island. Unfortunately, observations indicate that climate change is causing this to happen more frequently — as a result, larger and larger icebergs are appearing in the waters surrounding Antarctica, reports PHYS.org.

A team from Utrecht University is studying the routes that icebergs typically took during geological periods of rapid ice cap degradation, such as the end of ice ages. Understanding these routes provides essential insights into the impact of melting icebergs on the Earth's oceans, as well as the consequences of this process for the planet's future. Interestingly, in the process, the researchers also managed to find an explanation for the mysterious discovery of ancient material near the South Orkney Islands, located southwest of South Georgia. Previously, scientists had established that this material originated from Antarctica, but they did not understand how this was possible if Antarctica was not yet covered in ice at that time.

It is known that the Earth's ice caps grow when snow falls on their surfaces, and gravity gradually pulls them toward the sea. Here, they lose large volumes of ice due to melting and iceberg calving. If the growth of the ice cover keeps pace with the loss at the edges, it remains balanced and maintains the same size. However, under climate change conditions, where the air and ocean around the South Pole have warmed in recent decades, icebergs are breaking off more frequently and rapidly. Meltwater from above weakens the ice, and the warmer ocean thins the ice shelves. As a result, enormous chunks of ice can break away from the shelves in a short amount of time.

It is worth noting that scientists have been studying the sea around South Georgia, towards which the world's largest iceberg is heading, for years. The island is located in the middle of waters also known as the "Iceberg Alley" — a narrow strip of ocean filled with icebergs that have calved from Antarctica.

Since Antarctica has had a significant ice cap for about 34 million years, the remote islands around Iceberg Alley have witnessed countless icebergs. The South Orkney Islands are one of these islands, and in a 2017 study, scientists discovered something unusual here. They examined the area and found evidence of icebergs existing 3 million years before the formation of the Antarctic ice cap 34 million years ago.

The only way Antarctic debris could reach the islands is through icebergs that broke off from the ice continent and carried numerous fragments away. When the icebergs melted, these fragments settled on the ocean floor around the island.

In 2017, scientists were not surprised to find Antarctic debris near the South Orkney Islands, but they were quite astonished by its age. Analysis results indicated that the fragments are 37 million years old — 3 million years older than the major Antarctic ice cap. But how is this possible?

For a long time, scientists struggled to solve this mystery, but now Utrecht University student Mark Elbertsen has proposed a fairly simple explanation. The analysis was conducted in collaboration with Peter Beil from the Department of Earth Sciences and Eric van Sebille from the Institute of Marine and Atmospheric Research. The team used computer models to calculate the origins of the icebergs that reached the South Orkney Islands during the late Eocene, as well as how large the ice masses would need to be to reach the islands.

The results suggest that the Weddell Sea at that time was cold enough to transport medium-sized icebergs all the way to the South Orkney Islands. But that’s not all: the most logical starting point for the icebergs is also the bedrock, which matches the types of rocks found in the debris of the South Orkney Islands.

As a result, the researchers proposed that during the late Eocene, Antarctica likely had an ice cap that was large enough to reach the coastline. The team also believes that it was moving fast enough to produce sufficiently large icebergs capable of surviving in the warm Weddell Sea and reaching the islands.