Reducing ice could reawaken hundreds of volcanoes

As they melt , glaciers could expose hundreds of volcanoes they have until now hidden, causing explosive eruptions . This is indicated by research conducted on six volcanoes in the Chilean Andes by the University of Wisconsin-Madison, the results of which were presented in Prague at one of the most important international geophysics conferences, the Goldschmidt Conference. The link between melting glaciers and volcanic reawakening had been observed in Iceland in the 1970s , but only this research is based on global data, including data collected in continental areas.

The study, conducted with the University of California at Los Angeles, Lehigh University, and Dickinson College, used techniques such as argon dating and crystal analysis in igneous rocks. In this way, researchers led by Pablo Moreno-Yaeger reconstructed how ice pressure alters the characteristics of magma . They discovered, for example, that during the peak of the last Ice Age, between 26,000 and 18,000 years ago, the ice sheet favored a reduction in eruptions and the accumulation of silicate-rich magma reserves at depths of 10 to 15 kilometers.

When the ice melted rapidly at the end of the Ice Age, the Earth's crust relaxed and magma gases expanded, triggering explosive eruptions. "When ice shrinks due to global warming, volcanoes tend to erupt more frequently and explosively," Moreno-Yaeger said. This phenomenon is occurring in Antarctica , North America, New Zealand, and Russia.

The researchers also note that increased volcanic activity could have a significant impact on the climate . In the short term, eruptions release tiny gaseous particles (aerosols) that can temporarily cool the planet , as happened in 1991 when the eruption of Mount Pinatubo in the Philippines reduced global temperatures by about 0.5 degrees Celsius. However, Moreno-Yaeger notes, "over time, the cumulative effect of multiple eruptions can contribute to long-term global warming due to the accumulation of greenhouse gases, " and this "creates a vicious cycle, in which melting glaciers trigger eruptions, which, in turn, could contribute to further warming and melting."