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Why does low sunspot activity not fully explain the Little Ice Age?

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Line graph showing estimated temperature variations from 1000 to 2000 CE for the Northern Hemisphere and central England, with three lines representing different data sources. The chart highlights the medieval warm period around 1100-1300 and the Little Ice Age from about 1500 to 1850, followed by a sharp temperature rise in the late 20th century. Temperature is shown as deviations from the 1961-1990 average. — Little Ice Age Estimates of temperature variations for the Northern Hemisphere and central England from 1000 to 2000 ce.

While low sunspot activity—such as the Spörer Minimum and the Maunder Minimum—is associated with reduced solar output and colder temperatures in parts of Europe, it is not considered the sole cause of the Little Ice Age.

Scientists argue that low sunspot activity cannot fully explain the phenomenon for several reasons:

Geographic Inconsistency: The cooling episodes observed globally during this period did not occur simultaneously. The absence of sunspots fails to account for the specific timing and nature of brief cooling episodes that occurred in various regions outside of Europe.1
Multiple Drivers: Climatologists contend that the Little Ice Age was likely the result of a combination of factors rather than a single cause. In addition to solar variability, these include:
- Atmospheric circulation: Changes in large-scale patterns, such as a reversal of the North Atlantic Oscillation, significantly influenced regional climate variability.1
- Volcanism: Explosive volcanic eruptions can propel ash and gases into the stratosphere, reflecting solar radiation and leading to temporary global cooling.1