Volcanic eruptions in North America were more explosive in the past

London, June 17 (ANI): Scientists say that millions of years ago, volcanic eruptions in North America were more explosive and may have significantly affected the environment and the global climate.

"Past volcanic eruptions have had significant impacts on the environment. We humans have witnessed the various impacts of volcanic eruptions like the 1991 Mount Pinatubo and the more recent Icelandic one. The physical aspect of the impacts such as explosion or ash plumes is often short-lived, but the chemical consequence of its emitted massive gases can have a long-lasting effect on global climate," said Associate Professor Huiming Bao of LSU's Department of Geology and Geophysics.

Using computer models and geological data, Bao and his colleagues, Shocai Yu of the EPA and Daniel Tong of the National Oceanic and Atmospheric Administration, or NOAA, simulated the sulphur gas oxidation chemistry and atmospheric condition of the northern high plains region of North America.

Bao and his colleagues discovered that many of the volcanic ash beds are rich in sulphate, the product of atmospheric oxidation of sulphur gases. The distinct stale isotope signatures of these sulphates can reveal their oxidation pathways. According to Bao, sulphur dioxide gas is oxidized in the atmosphere, where it is turned into sulfate aerosol, which plays a very sensitive role in the rate and impact of climate change.

"These sulphate aerosol deposition events were so intense that the sulphate on the ground or small ponds reached saturation and gypsum mineral formed," Bao said.

"What we reported in our Nature paper is that there were many massive volcanic SO2 emissions and dense sulphate aerosol events in the northern High Plains of North America in the past. We show that in the past the sulphate aerosol formed in a very different way than today, indicating a difference in the past atmospheric condition or something peculiar with these explosive eruptions in the west," he added.

The research is published in the journal Nature. (ANI)