Final answer:
During low sunspot activity, total solar irradiance decreases slightly, but variations are minimal (around 0.1%) and their direct impact on Earth's climate is not fully understood, though effects on upper atmosphere chemistry are noted.
Step-by-step explanation:
During periods of low sunspot activity, total solar irradiance decreases slightly. However, satellite data indicate that variation in the Sun's total energy output throughout a solar cycle only changes by about 0.1%. It is essential to understand that while this might seem relatively insignificant, it can have a range of effects on Earth. For instance, during periods of low sunspot activity, like the Maunder Minimum, extreme ultraviolet radiation can decrease, potentially influencing the chemistry and temperature of the upper atmosphere, impacting ozone levels, and altering wind circulation patterns.
It is also noted that low sunspot activity has been historically associated with cooler climate episodes, such as during the Little Ice Age. Yet, there is no definitive model to explain how reduced solar activity directly causes changes in Earth's climate, and factors like volcanic activity contributing aerosols also play a significant role in climatic variations. The complex interaction between solar activity and Earth's climate remains an area of ongoing research and debate within the scientific community.