Volcanic Acidity (IMAGE) University of Copenhagen Caption This shows the bipolar matching of volcanic acidity spikes (sulphate) in Greenland and Antarctic ice cores at around the Toba eruption. Credit Niels Bohr Institute Usage Restrictions Niels Bohr Institute License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.