Would the occurrence of a Maunder-like solar minimum reverse the observed climate change?

Abstract

Abstract This study investigates a hypothetical scenario in which a prolonged solar minimum, such as the Maunder minimum, is combined with an increase in CO2 emissions observed during the postindustrial period. For that purpose, two fully coupled state-of-the-art Earth system simulations were performed spanning the period 1850–2000. From the year 1950 onwards, the radiative forcings differed. One accounts for the observed radiative forcing, including the increase in CO2 concentrations in recent decades, while the other adds the artifact of a decrease in the solar constant of similar magnitude as that which occurred during the Maunder minimum four centuries ago, maintaining the increase in CO2. The model was evaluated by comparing the results of the simulations with the ERA5 data and the reanalysis data from the 20th century, versions 2 and 3. In some evaluations in this study, meridional averages were calculated at 30-degree latitude intervals to observe the differences between the effects of the Maunder minimum in each region of the planet. It was possible to see good consistency between the temperature differences in the second half of the 20th century simulated by the CESM and the data from the reanalysis in all the regions analysed, with the CESM variability remaining within what was observed between the reanalysis products themselves. The results showed that, when comparing the period 1950–2000 with the period 1851–1949, the Maunder Minimum experiment mitigated the warming of the planet in this period by approximately 50%, although it was unable to reverse it. In the periods where the greatest warming was observed, at the end of the 20th century, the Maunder minimum had the most significant influence on reducing this warming in the Southern Hemisphere and in the section between 0–30°N; this warming could be reduced by almost 70%, and it had a smaller or almost zero influence in the region between 30–90°N. However, even though the Maunder minimum mitigates warming, this trend has not been systematically reversed worldwide.