Melting ice in Antarctica could wake sleeping volcanoes

Antarctica, a land of extremes, hides a fascinating and potentially impactful geological secret beneath its ice. Known for its towering Mount Erebus and iconic lava lake, the continent also harbors over 100 lesser-known volcanoes.

Many of these lie buried beneath kilometers of ice, especially along Antarctica’s western coast.

Antarctica’s hidden volcanoes

Climate change is causing Antarctica’s ice sheet to melt faster than before, which is raising global sea levels. But the impact doesn’t stop with the oceans.

The ice sheet is incredibly heavy and presses down on the land beneath it. When the ice melts, the weight on the rocks below is reduced, a process scientists call “unloading.”

This unloading has significant geological effects. The reduced pressure can increase the chances of volcanic eruptions.

Similar effects have been seen in other parts of the world, where melting glaciers and ice sheets have triggered increased volcanic activity.

In Antarctica, where many volcanoes lie buried under kilometers of ice, this unloading process could “awaken” these hidden volcanoes. Their eruptions could melt even more ice from beneath, amplifying the melting process in what scientists call a “feedback loop.”

This means that as the ice melts, it could trigger volcanic eruptions that further accelerate the melting.

Melting ice and subglacial volcanoes

A research team led by A. N. Coonin from Brown University used 4,000 computer simulations to study how melting Antarctic ice affects hidden volcanoes.

The results show that as the ice gradually melts, it can increase both how frequent and how powerful subglacial volcanic eruptions become.

This means that ice loss doesn’t just impact the surface – it also significantly affects Antarctica’s volcanoes deep below the Earth’s crust.

The phenomenon is linked to how magma chambers respond to changes in pressure. Magma chambers, located beneath the Earth’s surface, hold molten rock under high pressure.

Pressure inside of magma chambers

The massive weight of an ice sheet above a magma chamber keeps the pressure stable. When the ice melts, the weight is reduced, and the pressure on the magma decreases.

As the pressure lifts, the magma can expand. This expansion puts stress on the walls of the magma chamber, making eruptions more likely.

To make matters more complex, many magma chambers contain gases, such as water vapor and carbon dioxide, dissolved in the magma under high pressure. When the pressure reduces – similar to opening a soda bottle – these gases escape in bubbles, rapidly increasing the pressure inside the chamber.

This added pressure from escaping gases and expanding magma increases the chances of an eruption. The process is further intensified in regions like Antarctica, where ice loss directly impacts the stability of these underground systems.

Impact of subglacial eruptions

Subglacial volcanic eruptions rarely breach the surface, but their heat has significant consequences. They can intensify melting deep below the ice, weakening the ice sheet from within.

As discussed above, this weakening creates a feedback loop: as ice melts and pressure lessens, volcanic activity increases, which in turn accelerates ice melting.

The researchers emphasize that this is a slow process, unfolding over centuries. However, this slow feedback loop could persist even if humanity succeeds in curbing greenhouse gas emissions.

The process might have played a role in past volcano eruptions when Antarctica’s ice sheet was much thicker during the last ice age.

Interconnectedness of Antarctica’s volcanoes

Antarctica’s hidden volcanoes highlight that the impacts of climate change extend far beyond the atmosphere and oceans. They reveal how warming temperatures can initiate complex chain reactions deep within the Earth.

As the ice melts, it reduces pressure on underground magma systems, potentially triggering volcanic eruptions. These eruptions, in turn, can intensify ice melting, creating a self-reinforcing cycle.

Although this process unfolds over centuries, it serves as a powerful reminder of the interconnectedness of Earth’s systems. Geology and climate are not isolated – they influence each other in ways that can reshape the planet.

Understanding these hidden dynamics is essential as we address the long-term consequences of climate change. By studying these processes, we can better prepare for the challenges they may bring, even if their full effects seem distant today.

The study is published in the journal Geochemistry, Geophysics, Geosystems.

Image Credit: Josh Landis, U.S. Antarctic Program

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