The eruption of Mount Pinatubo in 1991 , the second largest terrestrial eruption of the 20th century , affected the climate substantially , subsequently global temperatures decreased by about 0.5 °C ( 0.9 °F ) for up to three years . Thus , the cooling over large parts of the Earth reduced surface temperatures in 1991 – 93 , the equivalent to a reduction in net radiation of 4 watts per square meter . The Mount Tambora eruption in 1815 caused the Year Without a Summer . Much larger eruptions , known as large igneous provinces , occur only a few times every 50,000,000 – 100,000,000 years through flood basalts ; in Earth 's past , they have caused global warming and mass extinctions
Year Without a Summer
Year Without a Summer
Climate change