Antarctica's volcanoes on the verge of awakening due to global warming ?

© United States Antarctic Program – Antarctic Photo Library

The White Continent is a world apart. Located around the South Pole, it is the southernmost and coldest continent on our planet. Covered 98% by ice, it is home to breathtaking landscapes and a unique biodiversity, adapted to extreme conditions. Although it is often nicknamed the “white desert” (because of the very low rainfall it receives), it is not just a long, arid and frozen plain, punctuated by a few glaciers.

It is actually home to dozens of mountains, valleys and above all more than a hundred volcanoes, some of which show worrying signs of activity. Global warming and melting ice could encourage their awakening, according to new studies conducted on Mount Erebus and Mount Waesche.

The natural laboratory of Mount Erebus

Mount Erebus (photo at the top of the article) is an exceptional case study in the field of volcanology. Culminating at 3,794 meters above sea level, it is the northernmost active volcano on our planet. Its permanent lava lake, a rare phenomenon in the volcanic world, has persisted for decades.

The latter, 20 meters wide, shelters complex dynamics that scientists are trying to decipher. ” We're looking at the tip of a magma system that extends perhaps 150 km into the mantle ,” says Rick Aster, a geophysicist at Colorado State University.

The new seismic facilities, deployed in extreme conditions where temperatures can drop to -59°C, as reported by Glen Mattioli, vice president of instrumentation at the EarthScope Consortium, will allow continuous monitoring of the activity of Mount Erebus.

Ronni Grapenthin, a geophysicist at the University of Alaska Fairbanks, points out a paradox about the latter. Although the lava lake theoretically acts as a pressure relief valve, long-term pressurization cycles inflate and deflate the volcano's flanks, suggesting a gap in understanding its magma system.

Although its internal dynamics are the ones being studied, melting ice could influence the stability of its volcanic system. Increased monitoring of Mount Erebus could thus help to better understand how external factors, such as melting ice caps, could act as a catalyst to awaken the volcanoes in this isolated but geologically active region.

The enigma of Mount Waesche

Research on Mount Waesche, located 1,500 km from McMurdo, a US base, reveals that there is a correlation between volcanic activity and climatic periods. Matthew Zimmerer and his team from the New Mexico Institute of Mining and Technology analyzed lava samples dating back more than 100,000 years. Their results, still unpublished, are nevertheless indisputable: “ The correlation was totally unexpected“, says Zimmerer.

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Geological records indicate that nearly 90% of eruptions occurred between ice ages, during warming phases similar to the one we are experiencing today.

A discovery that resonates with the observations of Adelina Geyer, a volcanologist at Geosciences Barcelona: “As soon as the glaciers begin to retreat, volcanic activity intensifies ». This phenomenon, already documented in Iceland and the northwestern United States, could be explained by a simple but formidable mechanism: the decrease in glacial pressure would release magmatic gases, like uncorking a bottle of champagne.

A domino effect with global consequences

The prospect of a volcanic awakening in Antarctica would be a new environmental problem to add to the (too) long list that already weighs on our shoulders. While an isolated eruption would only have a localized impact on glacial dynamics, the synchronous activation of several volcanic centers could trigger a cascade of events with considerable consequences.

The initial melting, caused by anthropogenic warming, would relieve the pressure on the magma chambers. This decompression would promote the release of volcanic gases and, by extension, the occurrence of eruptions. The latter would in turn accelerate glacial melting, thus creating a positive feedback loop likely to amplify the initial phenomenon.

If the melting of the ice accelerates, the phenomenon would have repercussions on the global ocean circulation, in particular by the massive influx of fresh water into the southern oceans. This change in the physicochemical parameters of the deep waters could disrupt the ocean currents, which act as thermal regulators of our planet.

This is why the scientific community is intensifying its research efforts on the active volcanoes of the South Pole. To better understand the interactions between climate and volcanism on the continent, a global approach to the issue is necessary, which involves a combination of different approaches: geological, geophysical and climatological. Integrating these feedback mechanisms into climate models will allow us to better anticipate and perhaps mitigate their consequences on the planetary balance.

• Melting ice in Antarctica could trigger an increase in volcanic activity, influenced by the release of pressure on magma chambers
• Studies show a link between periods of warming and peaks in eruptions, feeding a feedback loop with visible repercussions on glacial dynamics.
• This phenomenon could disrupt ocean currents and affect the global climate balance.

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