Imagining Antarctica without ice is not an exercise in extreme imagination, but a concrete way to understand how much the future of the planet is linked to what happens under that white blanket which has always seemed immobile and reassuring to us. Today we know that beneath kilometers of ice there exists a living, complex continent, sculpted by mountains, deep valleys, basins and canyons that directly influence the fate of the ice itself.
This is shown to us by Bedmap3, the most detailed map ever made of the Antarctic seabed, the result of over sixty years of research and surveys conducted by an international network of scientists led by the British Antarctic Survey. A patient work, stratified over time, which brings together data collected by planes, satellites, ships and even dog sleds, as if each era had left a useful trace to complete the puzzle.
Ideally removing the approximately 27 million cubic kilometers of ice that cover Antarctica means finally seeing the real shape of the continent. And it is precisely this form that makes the difference. The ice does not move randomly: it flows following the depressions in the ground, accelerates in the smoothest points and freezes where it meets ridges and reliefs. Knowing these details is essential to predict how the Antarctic ice sheet will react to rising temperatures.
Bedmap3 fills many of the gaps left by previous maps, especially in East Antarctica and along the western coasts, areas crucial to ice stability. The researchers added millions of new measurement points and, where it was not possible to directly detect the thickness of the ice, used mathematical models based on its natural flow. The result is a surprisingly clear photograph of what lies beneath the ice.
This precision matters because Antarctica holds enough water to raise sea levels by about 58 meters if it melted completely. A distant scenario, of course, but one that makes it clear how even partial changes can have enormous consequences for coastal cities around the world.
The map that tells of a greater fragility than expected
The new map confirms that the total ice volume is similar to previous estimates, but reveals greater vulnerability. Much more of the Antarctic ice, in fact, rests on rock that is below sea level. This detail makes the ice cap more exposed to the intrusion of warmer ocean waters, especially along the continent’s margins.
One of the most fascinating aspects of Bedmap3 is the ability to show the so-called subglacial channels, real preferential routes along which the ice slides towards the ocean. They are structures invisible from the surface, but crucial to understanding why some glaciers accelerate suddenly while others resist longer.
The map also overturned a certainty that seemed consolidated. For years it was thought that the point with the thickest ice was located in the Astrolabe basin, in Adélie Land. Today we know that the record belongs to an unnamed canyon in Wilkes Land, where the ice reaches nearly 15,000 feet thick. Numbers that help make the scale of what is at stake tangible.
Another novelty concerns the areas in which the ice shelves, although floating, temporarily touch the seabed during low tide. They are areas of unstable contact that influence both the movement of ice and the circulation of ocean water, and which until recently were almost ignored.
The most recent data tell a story that leaves no room for indifference. In 2023 alone, Antarctica lost 168 billion tons of ice, one of the highest values ever recorded. A loss that is part of a now clear trend: between 2002 and 2017 the melting of the large ice caps contributed about a third to the global rise in sea levels.
Looking at Antarctica without ice today does not mean imagining an apocalyptic future, but understanding how delicate the balance we are altering is. Bedmap3 is not a point of arrival, but an essential tool for reading the present and trying to prevent worst-case scenarios. Under that uniform white there is a continent that speaks. It’s up to us to decide whether to listen to it.
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