Fig. 5. Variations of the AA indices without GHGs forcing and with GHGs forcing during the past millennium and the industrial era.

The dark red line represents the ensemble mean of a three-member ensemble of climate model simulations driven with orbital forcing only. The dark blue line represents the ensemble mean of a three-member ensemble of climate model simulations driven with both orbital forcing and GHGs forcing. Light red and light blue shadings are minimum and maximum of the ensemble. The model simulations were provided by long-term ensemble simulation experiments³⁸.