Fig. 2: The increased convection around the MC and its underlying causes.

a Regressed SST anomalies (shading; unit: K), precipitation anomalies (contours; unit: mm day⁻¹), and 850-hPa wind anomalies (vectors; unit: m s⁻¹) during JJA(1) onto the standardized D(0)JF(1) Niño-3.4 index in the differences between the CO₂ RD and RU period for 9 models’ MME. For precipitation anomalies, solid contours represent positive values at 0.3 and 0.6 mm day⁻¹, while dashed contours indicate negative values at –0.3 and –0.6 mm day⁻¹. b Regressed meridional mean (10°S–5°N) vertical pressure velocity anomalies (shading; unit: Pa day⁻¹) and wind anomalies (arrows; units: Pa s⁻¹ and m s⁻¹) during JJA(1) onto the standardized D(0)JF(1) Niño-3.4 index in the differences between the CO₂ RD and RU period for 9 models’ MME. The brown dots in (a), gray grids in (b), and black arrows in (a), (b) denote that at least 70% models show consistent results. The red solid line rectangles in (a), (b) highlight the equatorial CP region, and the red dashed line rectangles highlight the MC region. c Evolution of the regressed precipitation anomalies in the MC (yellow line; unit: mm day⁻¹), SST anomalies in the equatorial CP (red line; unit: K), and SST anomalies in the MC (blue line; unit: K) during JJA(1) onto the standardized D(0)JF(1) Niño-3.4 index for 9 models’ MME. The green shadings correspond to the selected CO₂ RU (55–105) and RD (175–225) period. The dashed vertical lines indicate the year 140, when CO₂ concentrations peak.