VIDEOS: Lightning In the Erupting Calbuco Volcano. Plus: “So far the Calbuco eruption does not look to be as big as Mount Pinatubo in 1991 or Mount St. Helens in 1980. Pinatubo lowered global temperatures by about 0.5C. The big eruptions matter because they can cause climate changes that cause crop failures. An eruption on the scale of the 1815 Tambora eruption would cause massive crop failures and famine in many countries.”