The volcanic signal in surface temperature observations

Climate records of the past 140 yr are examined for the impact of major volcanic eruptions on surface temperature. After the low-frequency variations and El Nino/Southern Oscillation signal are removed, it is shown that for two years following great volcanic eruptions, the surface cools significantly by 0.1°-0.2°C in the global mean, in each hemisphere, and in the summer in the latitude bands 0° -30°S and 0° -30°N and by 0.3°C in the summer in the latitude band 30°-60°N. By contrast, in the first winter after major tropical eruptions and in the second winter after major high-latitude eruptions, North America and Eurasia warm by several degrees, while northern Africa and southwestern Asia cool by more than 0.5°C. -from Authors