We deduce temporal variations of the level of global lightning activity from the long-term Schumann resonance (SR) monitoring performed at the Tottori observatory (35.5 ¿N, 134.33 ¿E). The continuous analog records of the horizontal magnetic field cover the period from August 1967 to November 1970. The data show that temporal changes of the SR amplitudes vary considerably from day to day. Meanwhile, the regular diurnal and longer-scale variations appear after averaging. We found annual, and semiannual components in variations of global thunderstorm activity between 1967 and 1970. Comparison with the long-term SR records made recently in Europe allows us to demonstrate the similarity and stability of the global thunderstorm variations on a seasonal scale. Simultaneously, it revealed a contribution from winter thunderstorms in the Japan Sea to the Tottori SR records. ¿ 1999 American Geophysical Union