ABSTRACT
Sunspot cycle. The main known external causes of interannual climate variability and climate change are changes in solar output. The variation in solar output coincides with the most prominent and best-known solar distur bance of 11.08-year intervals, known as the sun spot cycle. Annual numbers of sunspots have been recorded for many years by astronomers, and these show the relative absence of sunspots from 1650 to 1700, the “Maunder minimum,” with a slight decrease in solar output (Eddy, 1976). This mini mum has been used by some to explain the Little Ice Age (1430-1850) in Europe. Estimates place the increase in solar irradiance between the Maun der minimum and now between 0.5 and 1.4 W m-2, or an increase of 0.3 per cent of the solar irradiance (IPCC, 1996).
