Schwabe_Gleissberg_1700-2020_1400.jpg

The amplitude of the 11-year solar cycle (formally called the Schwabe cycle, orange) is modulated by the approximately 100-year Gleissberg cycle (charcoal), in which a number of consecutive cycles of high activity are bracketed by consecutive cycles of lower activity. The start of the Industrial Revolution in the mid-1700s coincided with a Gleissberg maximum. The relatively high activity of the mid 20th-century also coincided with a Gleissberg maximum, while the recent decades coincide with a Gleissberg minimum. NOAA Climate.gov image based on data from Wang and Lean, 2021.