How severely have volcanoes contaminated the atmosphere with sulfur particles in past millennia? To answer this question, scientists use ice cores, among others, as climate archives. But the results differ, particularly in some major volcanic major events of the past, depending on whether the cores come from Antarctica or Greenland. Atmospheric scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Max Planck Institute for Meteorology in Hamburg have now found an explanation that could significantly improve the interpretation of ice cores. Their study was just published in the current issue of the internationally renownedJournal of Geophysical Research—Atmosphere.
Storms, cold, poor harvests—the year 1816 was a “year without a summer” in European history. The reason was the eruption of the Indonesian volcano Tambora a year earlier. It had thrown huge amounts of sulfur compounds into the stratosphere (at altitudes of 15-50 km) where they spread around the entire globe and significantly weakened solar radiation for several years afterwards. Such intense volcanic eruptions are quite common in Earth’s history. To better understand their impact on the climate and the atmosphere, scientists try to reconstruct those eruptions accurately. Important archives of information are ice cores from Greenland and Antarctica because the sulfur particles ejected from the volcano fall back to the surface. A portion of that fallout is trapped in the ice of the polar regions and can be analyzed even thousands of years afterwards. The former aerosol contamination of the atmosphere is derived from it using a simple ratio calculation.
But this method has its limitations. “Volcanic aerosols in the stratosphere absorb infrared radiation, thereby heating up the stratosphere, and changing the wind conditions subsequently,” said Dr. Matthew Toohey, atmospheric scientist at GEOMAR Helmholtz Centre for Ocean Research Kiel. Using an atmospheric model, he has now tested the effects of this phenomenon. “We have found that the deposition of sulfur compounds in the Antarctic after very large volcanic eruptions in the tropics may be lower than previously thought,” the atmospheric researcher summarizes the findings of the study which has just been published in the current issue of the international Journal of Geophysical Research – Atmosphere.
Read more at: Phys.org