What if the Sun enters a Maunder Minimum tomorrow?

The climate responses to the sustained multi-decadal total solar irradiance (TSI) decrease in the pre-industrial era and global warming scenario are examined using the NCAR Community Atmosphere Model version 3 (CAM3) coupled with a mixed-layer slab ocean model. Both global average and regional surface air temperature (SAT) changes simulated by the model in the pre-industrial era are similar to that derived from diverse proxy data, indicating the model captures the influence of solar change on climate in the past and is useful for projecting the impact of solar variation on future climate. Diagnostic analysis demonstrates that TSI reduction shifts the AO/NAO state to a more negative index, resulting in observed regional SAT change in the model. In addition, the positive sea ice-solar radiation feedback amplifies the surface cooling due to the TSI decrease. The global annual average cooling effect induced by the TSI decrease in the global warming scenario is reduced by about 27% relative to that in the pre-industrial epoch, partly due to the suppressed sea ice-solar radiation feedback and the enhanced greenhouse effect associated with the increase of CO2. However, regional SAT change is much larger than that in the pre-industrial era, resulting from the enhanced negative AO/NAO index in the global warming scenario. The warming will be more serious in the western Greenland, Central Asia and East Asia in global warming scenario when the TSI decreases. Both global average and regional changes induced by the TSI reduction in the global warming scenario are different from that in the pre-industrial era, indicating that the impact of grand-minimum-induced solar variation on climate depends on the atmospheric background trace gas composition.