Abstract

Reconstructions indicate that levels of solar activity have been relatively high for the past 70 years, and it has been suggested that the Sun might evolve towards a state of lower output over the next 50-100 years. This study presents sensitivity experiments with a state-of-the-art climate model to investigate the impact of reaching very low levels of solar output, similar to those thought to have occurred during the Maunder Minimum, by the middle of the 21st century. We also investigate the importance of spectral solar irradiance (SSI) changes by conducting two sets of experiments which span the current uncertainty in ultraviolet (UV) solar irradiance variability.

The results show that, whilst the overall impact on global mean temperature is small, such a decrease in solar activity over the 21st century has the potential to modify the winter-time signal of anthropogenic climate change in western Europe through modulation of the North Atlantic Oscillation. The amplitude of the signal depends on the assumed magnitude of UV variability in the model, thereby highlighting that constraining SSI variability remains a key factor for understanding solar influences on climate.