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Exceptionally warm water advances through the ocean depths towards Antarctica, amplifying scientists’ alert about the melting of ice shelves, the stability of glaciers, sea level risks, and possible changes in global ocean circulation
Exceptionally warm water advancing towards Antarctica worries scientists and amplifies the alert about the stability of ice shelves, global ocean circulation, and potential impacts on sea level. A long-term analysis identified that heat stored in the ocean depths is shifting closer to the continent.
Warm water advances towards Antarctica
The research was led by the University of Cambridge, in collaboration with the University of California, and published in the journal Communications Earth & Environment. The work gathered decades of ocean measurements made by research vessels and robotic floats, allowing for the tracking of changes that were previously unclear in the available data.
The team identified that a mass of warm water known as Circumpolar Deep Water has expanded and shifted towards Antarctica’s continental shelf over the past 20 years. This advance raises concern because this type of water can reach the lower areas of ice shelves and intensify melting from below.
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The Brazilian Air Force now has a colossal helicopter: the H125 from the TH-X project arrives with multi-mission technology, capacity for up to 6 occupants, high efficiency in military training and operation in extreme environments, strengthening the training of pilots for the FAB and the Brazilian Navy.
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Joshua Lanham, lead author of the study and researcher at Cambridge’s Department of Earth Sciences, stated that the scenario is concerning precisely because of the risk of ice shelf destabilization. Until now, scientists did not have consistent enough observations to confirm this warming trend in the depths of the Southern Ocean.
The study represents the first clear evidence of heat displacement from the ocean depths across the Southern Ocean. The trend had already been predicted by climate models related to global warming but had not yet been directly observed in the analyzed data.
Antarctica’s ice shelves act as natural barriers
Antarctica’s ice shelves play an important role because they act as barriers that slow the flow of glaciers and ice caps towards the ocean. When these structures lose stability, continental ice can advance more easily into the sea.
These ice reserves, together, contain enough fresh water to raise the global sea level by about 58 meters. This volume shows why changes in the stability of ice shelves are closely monitored by researchers studying climate and oceans.
The risk highlighted in the study is related to melting caused from below, when warm water reaches the base of these shelves. This process can weaken structures that, on the surface, act as a natural containment for ice coming from the interior of the continent.
The approach of Circumpolar Deep Water also indicates a change in the distribution of heat around Antarctica. This change involves not only local ice but also the mechanisms that help regulate ocean circulation on a global scale.
Ship and float data helped fill gaps
Historically, observations in the Southern Ocean relied on surveys conducted by research vessels approximately every ten years. These surveys recorded detailed information on temperature, salinity, and nutrients, but the long gaps between measurements made it difficult to track long-term changes.
To expand coverage, researchers incorporated data from the global network of autonomous Argo floats. These robotic devices float in the upper ocean layer and collect continuous measurements, offering more frequent records than traditional ship-based surveys.
Despite the advantage in frequency, Argo floats have not been in operation for as long as the ships used in detailed hydrographic sections. Therefore, the two types of information were combined to build a more complete view of ocean evolution.
The team used machine learning to combine data from the floats with long-term ship-based observations. The result was a detailed monthly record covering the last 40 years, revealing the gradual movement of warm water towards Antarctica.
Professor Sarah Purkey, from the Scripps Institution of Oceanography and one of the study’s lead authors, stated that the polar ice caps were protected by a layer of cold water. Now, ocean circulation appears to have changed, allowing warmer water to advance towards these areas.
Purkey also highlighted that the expansion of this warm water was already expected, because more than 90% of the excess heat associated with global warming is stored in the ocean. The Southern Ocean absorbs a large part of this heat, which reinforces the region’s importance in climate balance.
Change could affect global circulation, carbon, and nutrients
The implications of the change in heat distribution extend beyond Antarctica. Professor Ali Mashayek, from Cambridge, stated that the Southern Ocean plays a fundamental role in regulating global heat and storing carbon.
Changes in this region can influence how heat, carbon, and nutrients circulate through the global ocean. The redistribution of heat in the deep ocean, therefore, not only represents a local threat to ice shelves but also a sign of changes in the climate system.
In polar regions, dense, frozen water sinks to the depths of the ocean. This movement helps drive a global circulation system often described as a conveyor belt, responsible for transporting water masses around the planet.
This system includes the Atlantic Meridional Overturning Circulation, known by the acronym AMOC. It moves water through the Atlantic Ocean and is part of the global dynamic that connects polar regions, deep oceans, and heat transport patterns.
Climate models used by the IPCC suggest that rising air temperatures and the addition of freshwater from melting ice are reducing the formation of dense water in the North Atlantic. This process could weaken the AMOC.
Similar patterns are expected in the Southern Ocean. Models indicated that less cold, dense water would form near Antarctica, allowing warmer, circumpolar deep water to advance and occupy that space.
Lanham stated that this scenario is already appearing in observations. For the researcher, it is not just a future possibility suggested by climate models, but an ongoing process with impacts on the circulation of carbon, nutrients, and heat throughout the global ocean.
Antarctica, therefore, appears at the center of an observed change in the ocean depths. The approach of exceptionally warm waters reinforces the warning about ice shelves, sea level, and climate balance in a region decisive for global circulation.
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