Fig. 8: The critical periods and physical processes for the strengthened warming of the SST anomalies in MC.

a Hovmöller diagrams of the mixed-layer temperature tendency anomalies in the MC (unit: K month⁻¹) for 5 models’ MME. The \(\partial {T}^{{\prime} }/\partial t\) values are calculated as the difference in temperature anomalies between times \(t\) and \(t-1\). The difference term, \(\Delta \partial {T}^{{\prime} }/\partial t\), is calculated by subtracting the result of the initial period of the CO₂ RU phase. b Same as (a), but the combined contributions of thermodynamic and dynamic processes from mixed-layer temperature tendency equation. The gray grids in (a), (b) denote the region in which at least 70% models show consistent results. The dashed vertical lines in (a), (b) respectively denote the central year of RU period, the peak year of CO₂ concentrations, and the central year of RD period. The red solid line rectangles in (a), (b) highlight the critical periods. c Evolution of mixed-layer temperature tendency anomalies in the MC during FM(1) (grey solid line; units: K month⁻¹), the contribution of SWR anomalies (red solid line; units: K month⁻¹), and the contribution of SWR anomalies related to cloud (blue solid line; units: K month⁻¹) for 5 models’ MME. d Evolution of mixed-layer temperature tendency anomalies in the MC during JJ(1) (grey solid line; units: K month⁻¹), the contribution of LHF anomalies (red solid line; units: K month⁻¹), and the contribution of LHF anomalies related to wind speed (blue solid line; units: K month⁻¹) for 5 models’ MME. The green shadings in (c), (d) correspond to the selected CO₂ RU (55–105) and RD (175–225) period. The dashed vertical line in (c), (d) indicates year 140, when CO₂ concentrations peak. The prime symbols represent the anomaly caused by ENSO. The Δ symbols represent the deviation relative to the initial period of the CO₂ RU phase.