Scientists studying ice cores packing in some 60,000 years of history have found signs of thousands of volcanic eruptions across that time, stretching back to the last Ice Age – with 25 of the eruptions larger than anything Earth has seen in the last 2,500 years. Researchers excavated the cores near both poles: in Antarctica (where 737 eruptions were logged) and Greenland (where 1,113 eruptions were found). A total of 85 eruptions were large enough to leave evidence behind at both poles. That evidence takes the form of sulfuric acid deposits left behind by the eruptions. It gives researchers clues...