Solar cycles are 12 years, but grand solar cycles are every 350-400 years. Half way between grand solar cycles, we have a grand solar minimum, which is a period

Solar cycles are 12 years, but grand solar cycles are every 350-400 years. Half way between grand solar cycles, we have a grand solar minimum, which is a period of ~100 years where solar activity is suppressed throughout 12 year solar cycles. These coincide with population reductions throughout history (mini ice ages). Check out the Maunder Minimum for the last time this happened. We're heading into one now, there is no denying it.