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Does climate affect volcanic activity?

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Mt. St. Helens erupts in 1980. Photo courtesy USGS.

New research suggests melting ice sheets could trigger more vulcanism

By Summit Voice

SUMMIT COUNTY — Melting ice sheets may trigger an increase in global volcanic activity, according to researchers with the GEOMAR Helmholtz Centre for Ocean Research (based in Kiel, Germany), and Harvard, who matched historic geological records of vulcanism with warm climate periods.

“In times of global warming, glaciers on the continents are melting relatively quickly. At the same time the sea level rises. The weight on the continents decreases, while the weight on the oceanic tectonic plates increases. Thus, the stress changes within in the earth to open more routes for ascending magma,” said GEOMAR’s Dr Mario Jegen.

The basic evidence from a 10-year study of volcanoes in Central America, as researchers started identifying patterns.

“Among others pieces of evidence, we have observations of ash layers in the seabed and have reconstructed the history of volcanic eruptions for the past 460,000 years,” said GEOMAR volcanologist Dr Steffen Kutterol. “There were periods when we found significantly more large eruptions than in others” said Kutterolf,  lead author of a new Geology article disclosing the finings.

After comparing these patterns with the climate history, there was an amazing match. The periods of high volcanic activity followed fast, global temperature increases and associated rapid ice melting.

To expand the scope of their discoveries, Kutterolf and his colleagues studied other cores from the entire Pacific region collected as part of the International Integrated Ocean Drilling Program and spanning 1 million years of geological history.

“In fact, we found the same pattern from these cores as in Central America” said Jegen.

Together with colleagues at Harvard University, the geologists and geophysicists searched for a possible explanation. They found it with the help of geological computer models.

The rate of global cooling at the end of the warm phases is much slower, so there are less dramatic stress changes during these times.

“If you follow the natural climate cycles, we are currently at the end of a really warm phase. Therefore, things are volcanically quieter now. The impact from man-made warming is still unclear based on our current understanding” said  Kutterolf. The next step is to investigate shorter-term historical variations to better understand implications for the present day.

Some major recent volcanic eruptions have had significant affects on global climate, at least in the short term. Ash from the 1991 Mt. Pinatubo eruption encircled the Earth and by reflecting sunlight, cooled the planet’s surface by up to half a degree Celsius.

The rate of global cooling at the end of the warm phases is much slower, so there are less dramatic stress changes during these times. “If you follow the natural climate cycles, we are currently at the end of a really warm phase. Therefore, things are volcanically quieter now. The impact from man-made warming is still unclear based on our current understanding” says Dr Kutterolf. The next step is to investigate shorter-term historical variations to better understand implications for the present day.

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